Category Archives: Technical Textile

Protective Clothing for Chemical & Biological Warfare

Gas! GAS! Quick, boys!—An ecstasy of fumbling,

Fitting the clumsy helmets just in time;

But someone still was yelling out and stumbling

And flound’ring like a man in fire or lime . . .

Dim, through the misty panes and thick green light,

As under a green sea, I saw him drowning.

In all my dreams, before my helpless sight,

He plunges at me, guttering, choking, drowning.

. . . .—Wilfred Owen

The poetry, excerpted from Dulce et Decorum Est, was written by Lieutenant Wilfred Owen of the Royal Army, who was killed in action in France on 4 November 1918.

1. Introduction

In some sense all warfare could be called chemical warfare because every modern weapon depends upon some sort of chemical explosion to cause some sort of casualty. We will narrowly limit the phrase chemical warfare to refer to the type of warfare that employs weapons which use the toxic properties of certain chemicals to produce debilitating physiological and / or psychological effects on the enemy. Additionally, a chemical agent is a chemical compound that is used in chemical warfare.

The threat of terrorism on US soil, to include chemical warfare, has become so great that a whole new agency of the government is being formed to counter this threat. An estimated 34 countries, to include the US, have the capability to produce chemical agents as well as certain sub national groups.

The threat of chemical warfare has increased dramatically since the 1980s. Chemical agents, mustard and tabun, were used in the Iran – Iraq war. The most notable terrorist activity using chemical weapons during peacetime occurred during the morning hours of 20 Mar 1995 on a subway train headed for the central government district in Tokyo. Members of the Aum Shinre Kyo cult, a Japanese doomsday cult, punctured bags of sarin gas (a chemical agent) on the subway, killing 12 people and injuring many more. This was not the first time chemical agents have been used.

The first employment of chemical weapons in modern times was by the Germans at Ypres, Belgium, on 15 April 1915. That afternoon German units released an estimated 150 tons of chlorine gas against Allied troops. Its use was largely superceded by the use of phosgene, COC12, a denser vapor. Because of its density, phosgene does not rise as rapidly as chlorine gas, as the cloud of gas passes over the target area.

Still later in the war sulfur mustard (a liquid at ambient temperatures) was introduced. Sulfur mustard persisted in the area of impact meaning it did not readily evaporate. This agent remained as a hazard for a considerable period of time, thus acting as a barrier to troop movements. Mustard was subsequently used extensively and with decisive results by Italy in Ethiopia in 1935.

The organo-phosphorous compounds, also known as nerve agents, are considered the most dangerous class of chemical agents. These agents were first developed in the 1930’s, by the German scientist Gerhard Schrader, in conjunction with his research on insecticides. There are both persistent and non-persistent varieties. Nerve agents are a major component of the chemical arsenals of both the U.S. and the former U.S.S.R.        Chemical agents may be delivered by a wide variety of means: bombs; spray tanks; rockets; missiles; land mines; and artillery projectiles. Just the threat of their use can force military personnel to don cumbersome and uncomfortable protective clothing, thereby, greatly reducing their military effectiveness without any direct casualties.

In 1974, the U.S. signed the Geneva Protocol of 1925, which bans the use of poisonous substances in war. The U.S. reserved the right to retaliate in kind if an enemy uses any chemical agent against the US. The power to order such retaliation resides with the President. The U.S. has additionally renounced the use of herbicides and riot control agents in war, except in retaliation. (President Ford, 1975).

2. Chemical Warfare Agents:

2.1. Nerve Agents

Nerve gases are stored as liquids and are dispensed as either vapors or disperse droplets. The agents enter the body by inhalation or by skin absorption. Death from acute poisoning occurs in minute by asphyxia. If the dose is received through the skin, however, progressive symptoms are suffered over several hours, finally leading to paralysis and respiratory failure.

Nerve gas antidotes administered by self-injection are of limited effectiveness. The main line of defence is face masks to prevent inhalation and protective clothing to protect against skin absorption.

2.2. Blister Agents

Blister agents attack the lungs, eyes, and skin. They blister both skin and mucous membranes.

2.3. Blood Agents

Blood agents interfere with the bodies ability to absorb oxygen. The victim dies because the body tissues are starved of oxygen. Blood agents cause headaches, vertigo, and nausea before death.

2.4. Choking Agents

Choking agents attack the lungs, causing them to fill with fluid. Choking agents are detected by their smell and their irritancy. The victim suffocates by drowning in his own body fluid. Choking agents cause coughing, choking, tightness of the chest, nasea, headache, and watering of the eyes.

Table 1. Common Chemical Weapons

Name Odor Rate of Action Injuries Protection
Phosgene (CG) Freshly mowed hay, green corn Immediate to 3hrs Damages and floods the lungs Gas mask
Diphosgene (DP) Freshly mowed hay, green corn Immediate to 3hrs Damages and floods the lungs Gas mask
Sarin (GB) Almost none Immediate Difficulty breathing, death Gas mask and protective clothing
Soman (GD) Fruity, camphor odor Immediate Difficulty breathing, death Gas mask and protective clothing
VX None Immediate Death Gas mask and protective clothing
Hydrogen Cyanide (AC) Bitter almonds Immediate Blocks absorption of oxygen Gas mask and protective clothing
Cyanogen Chloride (CK) Bitter almonds Choking and breathing difficulty Gas mask
Mustard Gas – Distilled (MD) Garlic Hours to days Blisters, injures blood vessels, destroys tissues Gas mask and protective clothing
Nitrogen Mustard (HN) Fishy or musty 12 hours or longer Blisters, injures respiratory tract, destroys tissues Gas mask and protective clothing
Phosgene Oxime (CX) Sharp, penetrating Immediate Irritates mucous membrane of eyes and nose Gas mask and protective clothing
Lewisite (L) Geraniums Immediate Poisoning Gas mask and protective clothing
Mustard Gas / Lewisite Mix (HL) Garlic Immediate pain and blistering for twelve hours Blisters, injures blood vessels, destroys tissues, poisons Gas mask and protective clothing
CS Pepper Immediate Irritation Gas mask and protective clothing

Note: This chart is to be utilized as a rough guideline. Odor, Rate of Action and Injuries can very based upon concentration and chemical purity.

3. Individual Protection Equipments

The chemical–biological warfare threat can come in three possible physical forms: gas, liquid, and aerosol (ie, a suspension in air of liquid or solid particles). Protection against chemical agents disseminated as aerosols is especially difficult because the individual particles deliver a large amount of agent at a tiny site, thereby overwhelming the local capacity of the adsorbent.

Chemical agents can gain entry into the body through two broad anatomical routes: (1) the mucosa of the oral and respiratory tracts and (2) the skin. The icon of chemical warfare the gas mask protects the oral and nasal passages (as well as the eyes), while the skin is protected by the overgarment.

Total individual protection requires an integrated approach with the primary mechanism being respiratory protection which, when combined with an overgarment, gloves, and boots all properly fitted and used correctly, can provide excellent protection against chemical agents of all known types.

Common medical personal protective equipment used for standard precautions usually consists of   nonwovens or woven fabric suits or aprons, safety glasses, N-95 particulate respirators, and latex surgical gloves. These items, however, are not adequate for emergency chemical and biological warfare applications for a number of reasons.

Liquids and viruses readily penetrate uncoated clothing and masks, especially under pressure (eg, kneeling, leaning against objects). Chemicals readily permeate almost all coated or laminated breathable clothing. Latex surgical gloves are ineffective against chemicals because of permeation and against viruses because of penetration. Safety glasses do not protect against liquid splash, and medical shields do not stop chemical vapors or chemical or biological warfare aerosols. The N-95 respirators allow significant penetration through the filter (ie, 5%) and around the mask (i e, 10%). Typical interfaces between clothing, gloves, masks, and glasses do not protect against intrusion, including that of decontamination liquids.

The fundamental question of protective mask design was first addressed in World War I: should the mask completely isolate the soldier from the poisonous environment or should the mask simply remove the specific threat substance from the ambient air before it can reach the respiratory mucosa. The first approach requires that a self-contained oxygen supply be provided. Because of a multitude of practical logistical constraints (eg, weight, size, expense), this approach is not used except for specialty applications in which the entire body must be enclosed.

The more common practice has been to follow the second approach: to prevent the agent from reaching the respiratory mucosa by chemically destroying it, removing it in a nonspecific manner by physically adsorbing it, or both. Destruction by chemical reaction was adopted in some of the earliest protective equipment such as the “hypo helmet” of 1915 (chlorine was removed by reaction with sodium thiosulfate) and in the British and German masks of 1916 (phosgene was removed by reaction with hexamethyltetramine). More commonly, the removal of the agent was brought about by its physical adsorption onto activated charcoal. (Due to its mode of formation, this substance has an extraordinarily large surface area, some 300–2,000 m2/ g, with a corresponding plethora of binding sites.) It was soon recognized that impregnation of the charcoal with substances such as copper oxide, which reacted chemically with certain threat agents, further increased protection.

The effectiveness of modern masks depends on both physical adsorption and chemical inactivation of the threat agent. For example, in the M17 protective mask the adsorbent, known as ASC Whetlerite charcoal, is charcoal impregnated with copper oxide and salts of silver and chromium. The M40 protective mask uses an ASZ impregnated charcoal, which substitutes zinc for the hexavalent chromium (CrVI). The Centers for Disease Control and Prevention and the National Institute for Occupation Safety and Health have identified CrVI as a potential human carcinogen. A filter layer to remove particles and aerosols greater than 3 µm in diameter is also a component of all protective masks.

The location of the filters and adsorbent vis-a vis the respiratory tract was also one of the questions that mask designers addressed in World War I. In the standard British mask (the small box respirator of 1916), the filter and the adsorbent were contained in a separate container worn around the soldier’s trunk and connected to the mask by a hose. By way of contrast, in the standard German mask introduced in late 1915, the filter and adsorbent, contained in a small can (canister), were attached directly to the mask. The advantages of the canister arrangement were lighter weight and reduced work of breathing. But these advantages were gained at the expense of a smaller protective capacity and a degree of clumsiness associated with motion of the head. The canister is attached directly to the mask in the majority of modern protective masks. The contents of a modern canister are shown in Figure 1

Several of the essential features of modern protective mask design features that might be thought to be more recent also originated during World War I. For example, designing the inside of the mask so that inhaled air is first deflected over the lenses (which prevents exhaled air, saturated with water vapor, from fogging the lenses) and the use of separate one-way inlet and outlet valves (to minimize the work of breathing) were World War I–era inventions. The need of masked soldiers to be able to talk to one another was also recognized then. Interestingly, in the period after World War I, the U.S. Navy introduced the first useful solution to this problem: a moveable diaphragm held in place by perforated metal plates in the front of the mask. This device ultimately became the voicemitter found in today’s protective masks.

The protective masks issued to members of the U.S. armed forces protect the individual’s face, eyes, and respiratory tract from field concentrations of chemical–biological agents, toxins, and radioactive fallout particles. Several critical steps must be taken to ensure that an assigned mask will function properly in a toxic chemical environment:

• Select the correct mask size,

• Properly fit the selected mask,

• Validate the mask protection,

• Train the user in the proper wear and use of the mask, and

• Perform preventive maintenance checks on the mask as required.

4. Protective Clothing

There is a variety of protective clothing available for people working in situations in which they might encounter chemical or biological warfare agents. These clothing types include

  • Protective suits,
  • Gloves,
  • Boots, and
  • Hoods.

4.1. Protective Suits

The first thing purchasers of protective clothing usually ask for is test data determining barrier performance. When comparing barrier performance, a number of points should be kept in mind regarding the test parameters used, including

  • Contamination density, which can range from five grams per square meter to more than 100 grams per square meter;
  • Cell configuration ( eg, open or closed top);
  • Breakthrough endpoint—typically 4μg/cm2 for HD (ie, mustard gas);
  • Airflow; and
  • Test duration or mission length.

An overgarment can be made to protect skin from chemical agents by either physical or chemical means:

  • The overgarment can be made of fabric that is impermeable to most molecules, even to air and water vapor.
  • The overgarment can be made of fabric that is permeable to most molecules, but that also chemically alters or physically removes chemical agents before they reach the skin.

In the first method, the chemical agent is totally excluded because the agent is physically prevented from penetrating the substance of the overgarment. In the second method, the agent enters into the fabric of the overgarment but is absorbed before it can reach the skin. An overgarment made of an impermeable material such as Saran wrap or butyl rubber can offer complete protection against threat agents but at the unacceptable cost of causing heat injury. Cooling by sweating is not possible if water vapor cannot pass through to the ambient environment. Most fielded overgarments, therefore, depend on the fabric’s ability to adsorb the threat agent. Activated charcoal is used for this purpose in U.S. military designs.

Placing a soldier into full chemical protective equipment mask, overgarment, gloves, and boots is a decision that appropriately considers not only the protection aspect but also the added heat stress and potential for dehydration. The heat stress problem must be recognized from the start. Personnel must begin a drinking regimen prior to encapsulation to ensure that they do not become dehydrated quickly. The physical burden of a full ensemble can add 9 to 14 lb to a normal load; this added weight combined with heat stress, dehydration, and physical exertion can cause significant impairment to any mission. Because of these factors, the completeness of protection is stratified by the anticipated magnitude of the threat from chemical–biological agents: that is, the mission-oriented protective posture (Fig. 5). Five MOPP levels have been recognized previously, but with Change 2 to Field Manual 3-4, NBC Protection, the number was updated to seven in 1996.

4.2. Levels of Mission-Oriented Protective Posture (MOPP)

4.2.1. MOPP Ready

Soldiers carry their protective masks with their load-carrying equipment. The soldier’s MOPP gear is labeled and stored no further back than the battalion support area and is ready to be brought forward to the soldier when needed. The time necessary to bring the MOPP gear forward should not exceed 2 hours. A second set of MOPP gear is available within 6 hours. Units at MOPP Ready are highly vulnerable to attacks with persistent agents and will automatically upgrade to MOPP Zero when they determine, or are notified, that chemical weapons have been used or that the threat for use of chemical weapons has risen. When a unit is at MOPP Ready, soldiers will have field-expedient items identified for use.

4.2.2. MOPP Zero

Soldiers carry their protective masks with their load-carrying equipment. The standard battledress overgarment and other individual protective equipment that make up the soldier’s MOPP gear are readily available. “Readily available” means that equipment must either be carried by each soldier or be stored within the soldier’s arms’ reach (eg, within the work area, vehicle, or fighting position). Units at MOPP Zero are highly vulnerable to attacks with persistent agents and will automatically upgrade to MOPP 1 when they determine, or are notified, that persistent chemical weapons have been used or that the threat for use of chemical weapons has risen.

4.2.3.MOPP 1

When directed to MOPP 1, soldiers immediately don the battledress overgarment In hot weather, the overgarment jacket may be unbuttoned and the battledress overgarment may be worn directly over the underwear. M9 or M8 chemical detection paper is attached to the overgarment. MOPP 1 provides a great deal of protection against persistent agents. The level is automatically assumed when chemical weapons have been employed in an area of operations or when directed by higher commands.

4.2.4 MOPP 2

Soldiers put on their chemical protective footwear covers, green vinyl overboots, or a field-expedient item (eg, vapor-barrier boots), and the protective helmet cover is worn. As with MOPP 1, the overgarment jacket may be left unbuttoned but the trousers remain closed.

4.2.5 MOPP 3

Soldiers wear the protective mask and hood. Again, flexibility is built into the system to allow the soldier relief at MOPP 3. Particularly in hot weather, soldiers may open the overgarment jacket and roll the protective mask hood for ventilation but the trousers remain closed.

4.2.6 MOPP 4

Soldiers will completely encapsulate themselves by closing their overgarments, rolling down and adjusting the mask hood, and putting on the NBC rubber gloves with cotton liners. MOPP 4 provides the highest degree of chemical protection, but it also has the most negative impact on an individual’s performance.

4.2.7 Mask-Only Command

Only the protective mask is worn. The mask-only command is given in these situations:

I.      When riot control agents are being employed and no chemical or biological threat exists.

II. In a downwind vapor hazard of a nonpersistent chemical agent. The mask-only command is not appropriate when    blister agents or persistent nerve agents are present.

4.3. Protective Ensembles

Most of the armies of the world have chemical protective clothing available for individual protection. Several types are available, depending on the protection required to perform a specific mission and whether the protective clothing needs to be permeable or impermeable. Most troops use permeable protective clothing, which allows for air and moisture to pass through the fabric without hindering the chemical protection capabilities of the clothing. This type of permeable protective clothing is described in the following section.

4.3.1 Battledress Overgarment (BDO)

The current standard A protective overgarment is the battledress overgarment (BDO). The BDO protects the wearer from all chemical agent vapors, liquid droplets, biological agents, toxins, and radioactive alpha and beta particles; however, the BDO does not stop either X or gamma radiation. The BDO protects the wearer for 24 hours after contamination from chemical agent vapors, liquids, and droplets; and biological agents and toxins. The effectiveness of the BDO is in its serviceability. Wear time of the BDO begins when it is removed from the sealed vapor-barrier bag and stops when it is returned to the vapor-barrier bag. Wearing the BDO for any part of a day constitutes a day’s wear.  The BDO becomes unserviceable if it is torn, ripped, a fastener is missing or broken, or petroleum, oils, or lubricants are splashed or spilled on the over garment. This unserviceableness necessitates replacement. The BDO is manufactured in two layers: a tightly woven outer layer and a charcoal-impregnated inner layer to adsorb agent liquid or vapor (Fig. 6). The garment consists of a hip-length coat and trousers with appropriate fasteners and multiple pockets. It is manufactured in eight sizes ranging from XXX Small through XX Large. The BDO is not designed to be decontaminated or reimpregnated for reuse. 

4.3.2 Aircrew Uniform, Integrated Battlefield

The aircrew uniform, integrated battlefield (AUIB) is designed to replace the BDO, the chemical protective overgarment (CPOG), and the Nomex flight suit for aircrews operating in a contaminated environment (Fig. 7). It is also designed to protect against petroleum and oils. It provides flame resistance as well as NBC protection. The outer shell is a laminate of 95% Nomex/5% Kevlar. While the inner layer is a 90-mil, carbon-impregnated, flame-resistant foam/nylon laminates. The AUIB is designed as a two-piece garment with a coat and trousers with appropriate fasteners and is available in woodland or desert camouflage. The heat stress burden of the AUIB is similar to that of the BDO.

4.3.3 Chemical Defense Aircrew Ensemble

The chemical defense aircrew ensemble (CDAE) is the newest generation of aircrew protective clothing. It is a one piece garment consisting of the Nomex flight suit, a charcoal undergarment, and long cotton underwear. The CDAE incorporates carbon-sphere technology to adsorb chemical agent. It is basically two suits differing in color: the CWU-66/P is green and the CWU-77/P is brown. It may be laundered as many as 10 times prior to chemical agent exposure without destroying the protective capabilities of the coverall.

4.3.4 Protective Clothing Based on Selectively Permeable Membrane Technology

Scientists at the U.S. Army Soldier Systems Center (Natick) are making historic strides in developing CB protective gear for the soldier. This new generation of lightweight chemical and biological protective clothing is based on selectively permeable membrane technology. The two membrane systems being investigated are the amine-based membrane/fabric system and the cellulose-based membrane fabric system from W.L. Gore & Associates, Inc. and Akzo Nobel, respectively. The selectively permeable membrane technology will reduce or eliminate the use of carbon in CB protective clothing. Since carbon adds weight and bulk, the protective overgarments fabricated from the new materials are dramatically lighter than their predecessors. The new protective overgarments weigh 51 percent less than the standard battledress overgarments (BDO) and 45 percent less than the Joint Service Lightweight Integrated Suit Technology (JSLIST) overgarment. In addition to being lighter weight, the new garments are easier to launder, and take up less package volume. Thus, the new protective gear will be an improvement over its predecessors from a logistical standpoint as well.

The novel materials provide protection against highly toxic compounds, including offensive chemical and biological agents. Incredibly, the resultant thin, lightweight, flexible material system also allows moisture vapor to pass through the clothing, thus providing relief from heat stress through evaporative cooling. The system is waterproof as well, and therefore, will provide protection from wet weather. The novel materials will also be incorporated into gloves and socks.

novel materials will also be incorporated into gloves and socks.

According to Mr. Truong, “Protective clothing is now worn over the Battle Dress Uniform (BDU). In the future, however, the selectively permeable membrane will allow the BDU itself to be the protective garment, thus, eliminating the need for an overgarment, especially in a high-threat scenario. As a result, the logistics burden, the weight, and the cost of the clothing system, as well as heat stress will be reduced.”

The two membrane technologies have been tested extensively and successfully on the Thermal Manikin. Soldiers who have assessed the new ensemble for comfort and durability in limited field tests have rated it highly.

In addition to the war fighter, the new protective clothing systems will also be useful to environmental cleanup personnel, emergency responders, medical personnel, industrial-chemical handlers, and pesticide handlers. The material could also be used as a sophisticated filter, separating chemicals from water vapor and/or other chemical species.

4.4 Joint Service Lightweight Integrated Suit Technology

The Joint Service Lightweight Integrated Suit Technology (JSLIST) program is developing the next generation of overgarment, which will be fielded in Fiscal Year 1997. The JSLIST program provides the future whole-body chemical–biological protective equipment for the joint services (U.S. Army, Navy, Air Force, and Marine Corps). The JSLIST program encompasses a lightweight garment (undergarment, overgarment, duty uniform) and improved chemical protective hand wear and chemical protective overboot. It will provide less bulk and heat stress by being constructed of state-of-the-art materials (the exact materials are not yet known, however) and will be more durable and launderable than current designs. The items in the JSLIST series are joint-service standardized items and are planned to be used by all services.In addition to the JSLIST, new agent-impermeable materials are being evaluated in conjunction with advanced fabrics to replace the carbon-impregnated fabrics, which have limited lifetimes. These new materials will be lighter, allow permeation of moisture while retaining protection, and cause less heat stress.

4.4.1 JSLIST Overgarment

The JSLIST Overgarment (OG) is a universal, lightweight, two-piece, front-opening garment that can be worn as an overgarment or as a primary uniform over personal underwear (Fig. 10 a). It has an integral hood, bellows-type pockets, high-waist trousers, adjustable suspenders, adjustable waistband, and waist-length jacket. This design improves system compatibility, user comfort, and system acceptance, and maximizes individual equipment compatibility. The JSLIST OG provides optimum liquid, vapor, and aerosol protection and also flame protection.

4.4.2 JSLlST Aviation Overgarment

The JSLIST Aviation Overgarment (AVOG) is the aviator’s version of the JSLIST OG and Duty Uniform (DU) configurations. It is a two-piece, front-opening, flame-resistant garment designed as a chemical protective overgarment or uniform. For cockpit compatibility, the integral hood and bellows-type pockets of the OG and the DU have been replaced with a crew type collar and sewn-down pockets (Fig.10 b).

4.4.
3 JSLIST Duty Uniform

The JSLIST Duty Uniform (DU) is a universal, lightweight, two-piece, front-opening garment that is worn as a primary uniform over personal underwear. It has an integral hood, bellows-type pockets, high-waist trousers, adjustable suspenders, adjustable waistband, and waist-length jacket (Fig.10 c). This improves system compatibility, user comfort, system acceptance, and ensures maximum individual equipment compatibility. The DU provides optimum liquid, vapor, and aerosol protection as well as flame protection.

4.4.4 JSLIST Vapor Protective Flame-Resistant Undergarment

The JSLIST Vapor-Protective, Flame-Resistant Undergarment (VPFRU) is a two-piece (jacket and drawers), front-opening, vapor-protective garment (Fig.10 d). It is configured with an integral form-fitting hood and detached vapor-protective, fire-resistant socks. Worn under standard duty uniforms, including the combat vehicle crewman coveralls and battledress uniform, the VPFRU is designed to provide the chemical vapor and biological agent protective layer. For Special Operations Forces and armor crews, the VPFRU is intended to provide maximum vapor and aerosol protection and MOPP flexibility.

4.5 Protective Boots and Gloves

A soldier wearing the chemical protective boots and gloves discussed here will soon realize that mobility is compromised by the boots and that tactile ability is degraded by the gloves. The present boots provide good protection against chemical warfare agents but are only an interim solution to the need for combined chemical protection, ease of decontamination, and safety. Wearers are at serious risk of falls due to the lack of adequate traction, and the weight of the boot contributes to the increased fatigue from complete protection ensemble wear. The boots do not protect the wearer from heat or cold and in some cases may contribute to medical problems such as trench foot, frost bite, or other cold weather injuries. The protective gloves degrade tactility and again will not protect against heat or cold and may increase the chance of cold weather injuries if the work glove is not worn over the protective glove. The following descriptions of protective boots and gloves are based on information from NBC Protection.

4.5.1 Chemical Protective Footwear Cover

The chemical protective footwear cover (CPFC) is an impermeable black butyl rubber footwear cover that protects the combat boot from all agents (Fig. 11). The CPFC has an unsupported butyl rubber sole and butyl rubber uppers with long laces, which fasten a front eyelet with side and rear eyelets. The CPFC can be decontaminated with 5% chlorine solution, then inspected and reused. If exposed to DS2, the CPFC should be washed since DS2 causes the rubber to deteriorate. The CPFC offers poor traction and the laces can cause a tripping hazard when the wearer is moving. Again, the CPFC offers no protection against cold; therefore, suitable precautions must be taken. Refer to NBC Protection5 for protective capabilities.

4.5.2 Chemical Protective Glove Set

The chemical protective glove set consists of an outer glove for chemical protection and an inner glove for perspiration absorption. The outer glove is made of impermeable butyl rubber and the inner glove is made of white cotton. The gloves come in three thicknesses: 7, 14, and 25 mil. Soldiers such as medical, teletypist, and electronic repair personnel, whose tasks require extreme tactility and sensitivity, and who will not expose the gloves to harsh treatment, will use the 7-mil glove set. Aviators, vehicle mechanics, weapons crews, and other soldiers whose tasks require tactility and sensitivity will use the 14-mil glove set (Fig.12). Soldiers who perform close combat tasks and other heavy labor tasks will use the 25-mil glove set. All of the glove sets protect against liquid chemical agents and vapor hazards. However, if the 7- mil glove set is contaminated, it must be replaced or decontaminated within 6 hours after exposure. The 14-mil and 25-mil glove sets will provide protection following contamination for 24 hours. All three glove sets can be decontaminated with a 5% bleach-and-water solution or a 5% HTH-and water solution, then inspected, and reused. All gloves will become sticky and soft if exposed to DS2 or petroleum-based fluids and must be replaced. Replacement must occur following damage or degradation or both. Refer to NBC Protection for protective capabilities.

4.5.3 JSLIST Improved Chemical and Biological Protective Glove

The JSLIST Improved Chemical and Biological Protective Glove (ICBPG) are designed to provide protection against chemical and biological agents in liquid, vapor, and aerosol form (Fig.13). Its protection performance is not degraded by exposure to petroleum, oil, and lubricants and to field decontaminants. To prevent excessive moisture buildup and improve user comfort, the ICBPG is semipermeable. The glove can be worn for up to 30 days without performance degradation and is flame resistant.

4.5.4 JSLlST Multipurpose Overboot

The JSLIST Multipurpose Overboot (MULO) is designed to be used for daily wear as required by the weather and is flame resistant. It is a single-piece design with webbed straps, side-to-back chemical-resistant plastic buckle closures, and improved tread design (Fig 14). Protection is provided for environmental hazards as well as chemical and biological agents. Additionally, the resistance to agents is not degraded by exposure to petroleum, oil, and lubricants, and decontaminants.

5. References

  1. William J. Daniels and Stanley A. Salisbury, Chemical and Biological Terrorism Preparedness— Web-Based Resources, Applied Occupational and Environmental Hygiene, Vol. 15 (8), 592–595, 2000.
  2. Jean McGrath, Chemical Warfare Agents, Toxalert, Vol. 19 (1), Feb 2002.
  3. Annetta Watson and Veronique Hauschild, Evaluation of Percutaneous Vapor Toxicity for Certain Chemical Warfare Agents: Application to Selection Guidelines for Protective Ensembles, Phd Thesis Research and Technology Directorate of the Soldier and Biological Chemical Command, APG, MD.
  4. WWW.firechief.com.
  5. Dr. Eugene Wilusz, Materials Technology For Chemical/Biological Protective Clothing, Natick Soldier Center U.S. Army Soldier
  6. Jack Sawicki, Protection from chemical and biological warfare, Surgical Services Management, Vol 5, No 9, 11-17.
  7. Frederick R. Sidell, M.D., Ernest T. Takafuji, M.D., M.P.H., David R. Franz, D.V.M, Ph.D., Medical Aspects of Chemical and Biological Warfare, Published by the Office of The Surgeon General at TMM Publications Borden Institute Walter Reed Army Medical Center Washington, DC 20307-500.
  8. L. Ashok Kumar & R Senthil Kumar, Protective Textiles, Asian Textile Journal, Nov 2004, 93-106.
  9. F.L.Cook, Chemical Warfare Fabrics: New Textile Market, Textile Month, Sep 1981, 115-121.

 

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Bio-Barriers

1. Introduction:

Walking through a forest, park, or even in yard, the graceful beauty of trees pleases the eye as it provides welcome shade, and makes us all breathe a bit deeper. Adding trees to a landscape increases the visual value of a property, and perhaps the monetary value as well. We’ve even found a way, using containers, to bring large trees indoors, to aesthetically enhance our interiors, such as malls and office buildings.

Tree roots are very aggressive, growing near the soil’s surface in search of water, nutrients, and oxygen. They can extend underground, spreading outward, two to three times the diameter of the tree canopy. As the tree grows, the roots grow, becoming larger and larger, exerting tremendous pressure on concrete and asphalt. These same roots can encroach on turf grasses in all landscape environments, including parks, golf courses, schools and green belts, and interfere with mowing equipment, as well as pedestrian traffic. The severe problems of tree root damage, tree loss, and our ability to manage the living root system has led to the invention of the tree root barrier.

Controlling soil erosion over buried hazardous waste is essential, so workers often plant vegetation to stabilize soil. Although vegetation is a viable, long-term means of stabilizing soil, it is critical that plant roots not intrude into buried waste.If roots are not excluded, they can disrupt the seal of water diversion layers and clay barriers in place over waste containers. If water penetrates these seals and filters into the waste, groundwater contamination may follow.Also, the roots could absorb some waste and transfer it into the environment, including the food chain. Thus, plant roots that intrude into hazardous waste burial sites can reduce the longevity and effectiveness of these sites.

Suppression or elimination of weed growth is a major component of all landscape maintenance programs. Weeds are undesirable due to aesthetic detraction; competition for light, water, nutrients, and space; provision of insect and disease habitats; and possible allelopathic growth suppression.

Most landscape maintenance programs rely on hand weeding, herbicides, and mulches (alone or in combination) to suppress and control weeds. Black plastic has traditionally been used by many landscapers to enhance the effectiveness of organic and inorganic mulches, but several studies have reported adverse effects on landscape plant growth due to its use.

Within the past few years, a new group of synthetic materials has been introduced for use with mulches for landscape weed control. These geotextiles (also called landscape fabrics or weed barriers) have one major advantage over plastics — they permit the exchange of water and air between the soil and the atmosphere.

2. Root Barriers:

The act of cutting off the roots of trees that are growing near a building and installing a barrier to prevent their reestablishment in the area where they are not desired is called installing a root barrier, a root wall, or root capping. The need for root barriers is related to the fact that expansive clay soil shrinks as it dries out. Any structure that expansive clay soil is supporting will move downward as the soil dries and shrinks. If the soil dries on one side of the structure and not the other, the soil shrinks where it has dried and remains expanded where it has not dried, causing the structure to experience differential settlement. Differential settlement can cause serious damage to a structure.

A root barrier is usually installed between concrete foundations or flatwork and adjacent trees within their mature height from the foundation and where there is expansive clay soil to prevent tree roots from consuming moisture from the soil under the area of concern. The barriers are installed so that they intersect imaginary radial lines extending from the trunk of the tree to the edges of the foundation. Root barriers can prevent damage to flatwork concrete such as walks and drives or to concrete slab on grade foundations. In some cases it is possible that differential settlement that has occurred because of shrinking soil can be reversed. The soil under a structure will swell or expand as it becomes rehydrated and in doing so will lift the portion of the structure that has experienced differential settlement back to near the level of the structure where differential settlement has not occurred.

Large trees with tap roots, such as pecan trees, may affect soil volume to a depth greater than the 30 inches indicated above. There is evidence that large pecan trees dry soil to the “water table” which causes it to shrink for a great depth. Where pecan trees have been removed to construct a building, the soil where the pecan tree was removed has swelled, causing significant damage to the interior of the structures. Pecan trees existing near a building have caused less differential movement during extended dry periods than other trees, probably because the tap root obtains a large amount of the trees’ water requirement from the “water bearing strata” usually found within 20 feet of the surface. Root barriers between pecan trees and similar type trees do have the effect of reducing shrinking of the soil on which a building rests.

3. Weed Barriers:

Landscape fabric (or geotextiles) can play a valuable role in various applications for weed control. including shrub beds, tree wells, and other mulched or gravelled areas. Since landscape fabric is usually included “within” a feature (e.g., under a layer of mulch and around ornamental plantings in a shrub bed), it is highly preferable that they are installed during the initial construction of the feature. However, they can also be retrofitted to many landscape features. Geotextiles can provide significant benefits by reducing maintenance requirements and the need for herbicide use for weed control. Proper material selection and installation procedures are important to ensure the effectiveness of geotextiles.

Placing landscape fabric under mulch provides greater weed control than mulch used alone. Fabrics differ in their weed-control abilities. Landscape fabrics that are thin, lightweight or have an open mesh allow greater weed penetration than more closely woven or nonwoven fabrics. A rock mulch above a landscape fabric can provide greater weed control than organic mulch above a landscape fabric.

Black plastic (solid polyethylene) provides excellent control of annual weeds and suppresses perennial weeds, but restricts air and water movement. Also, ants are attracted to soil that’s protected from rain. For these reasons, you may prefer a different long-term weed control method.

Thermally spunbonded fabrics are much more effective than woven or needle punched geotextiles in preventing fine roots and rhizomes from penetrating the fabric. Heavier weight fabrics should be used for sites that do not have frequent maintenance intervals. When installing geotextiles, potentially damaging objects (i.e., large angular rocks; pointed sticks) should be removed from the site and the soil should be graded so the fabric will lay smooth and flat on the ground. Where potentially difficult to control weeds are abundant (e.g., quackgrass), an herbicide may be desirable or necessary to prevent weeds from growing to and through seams and edges from below. In some settings, a shallow trench (2″-3″) around the perimeter of the installation site is helpful to hold the edges in place and keep them from becoming exposed. Seams should be overlapped 6″-8″ and the fabric should be tightly fitted around any objects. Where fabrics may become exposed and subjected to vandalism they should be pinned firmly to the ground, especially around the perimeter. The fabric should then be covered with 2″-3″ of mulch because ultraviolet light is damaging to most geotextiles and they should always be adequately covered. When properly installed, geotextiles will last indefinitely.

Yellow nutsedge grows through all landscape fabrics, but some fabrics are better at suppressing this weed. Black landscape plastic is ineffective, because the sharp points at the ends of leaves can penetrate the plastic. DuPont Typar 307 or 312 and Weed Barrier Mat are the most effective fabrics at controlling nutsedge plants. Geoscape Landscape Fabric and DeWitt pro-5 were slightly less effective, but much better than black plastic.

4. Bio-Barrier®:

Biobarrier® is an award winning, state-of-the-art technology using the finest materials. Designed as a long-term solution for vegetative root intrusion and possible structure damage, Biobarrier combines a proven geotextile fabric with the effective pre- emergence herbicide, trifluralin. Trifluralin, the active ingredient in Biobarrier, has been used extensively in commercial applications for more than 35 years and is widely recognized as a leading pre-emergence herbicide.

Utilizing a patented controlled-release process, Biobarrier delivers only the amount of trifluralin biologically necessary to inhibit root growth. Biobarrier’s innovative technology ensures that precise amounts of herbicide will be dispersed at the correct location for an extended time. This provides a distinct advantage over repeated applications of herbicides required by conventional methods.

4.1. Mechanism:

Biobarrier® consists of composite nodules injection-molded through Typar®, a spunbonded polypropylene geotextile fabric. The through injection molding technique ensures permanent nodule attachment. Impregnated with trifluralin, the nodules function as a protective reservoir. The nodule composition is designed to slowly release trifluralin vapors which adsorb in the soil.

Outside the nodule, the trifluralin degrades but is continuously replaced by new material, building and maintaining a root inhibition zone. Accurate nodule spacing ensures the individual nodule zones overlap and reinforce each other. At equilibrium, the inhibition zone becomes contiguous, enveloping the Biobarrier fabric.

When roots enter the inhibition zone, root tip cells cannot divide, preventing growth in that direction. Trifluralin is not systemic; therefore, it is not taken into the plant. As a result, the root system is diverted away from the Biobarrier-protected structure without adversely affecting the desirable plants or trees. Root branches outside of the zone are not affected.By utilizing a technology which combines a proven geotextile drainage fabric with an effective preemergence herbicide, Biobarrier II, marketed as a preemergence weed control fabric for landscaping, prevents grass and weed growth without affecting desirable plants. When covered with 2″ (50 mm) of mulch , stone, or other medium, the trifluralin inhibition zone both above and below the plane of the fabric blocks grass and weeds from establishing a viable root system needed to support growth. Additional protection is provided by the 4 oz./sq. yd. (136 g/sq. m) geotextile fabric which blocks existing grass and weeds from coming up through the fabric. New plants or desirable existing plants which have roots below the 2″ (50 mm) inhibition zone are not adversely affected.

The root inhibition zone is created and maintained by the trifluralin released from the nodules. Consequently, the highest trifluralin concentration in the soil is at the plane of the barrier, with concentration levels diminishing as distance from the barrier increases. The concentration level effective for all roots measured is less than 7.6 ppm. Plant species vary in resistance to trifluralin. This concentration level at zone equilibrium, based on field and laboratory measurements, occurs approximately 1″ (25 mm) from the barrier. Some root branch elongation may occur after the root tip meets the effective concentration level, pushing the tip within the 1″ (25 mm) zone.

4.2. Technical Data:

The hemispherical shaped nodules on Biobarrier contain one active ingredient(trifluralin) and two inactive ingredients (polyethylene and carbon black). Biobarrier is engineered to release the trifluralin very slowly in vapor form and establish a narrow(see chart below) protective chemical zone in soil adjacent to the fabric. This unique delivery method, combined with the chemical characteristics of trifluralin detailed below, ensure that the chemical zone remains very near the fabric and does not present a significant leaching problem. Trifluralin has been used extensively in commercial applications for over 35 years and widely recognized as a leading preemergence herbicide. See EPA Toxicity Rating for trifluralin below.

4.3. Application Categories:

Biobarrier® is utilized in many ways to accomplish the common goal of preventing root intrusion and possible structural damage. The major application categories are: (1) Vertical, (2) Horizontal and (3) Surround, as illustrated below.

Vegetation roots are opportunistic, traveling long, erratic paths – when necessary – to survive. Lateral root growth, however, predominates. Under most conditions, 80% of the roots occupy the upper 18 inch (460mm) layer immediately below the grade level. Root system growth patterns are influenced by environmental and soil conditions. Typically, dry climate species’ roots grow deeper. Densely packed soils, rock stratum, etc. sometimes produce the unexpected. The tree drip line is not a growth limitation.

Biobarrier is almost always used to exclude roots by diverting the growth path from protected areas. When used to confine root systems, care must be taken to provide sufficient soil volume within the confined area to support the mature species. Without sufficient soil volume, aerial growth will be stunted. In the worst case, the species will die from lack of nutrients, as with any method of reducing root growth.

4.3.1. Root Control Application:

Biobarrier Root Control installations effectively divert lateral root growth. They are used to prevent hardscape damage by root encroachment and to separate root systems for nutrient allocation or to isolate diseased root systems.

In a vertical application, the top edge of the barrier is always positioned 1″ (25 mm) below the soil surface. Selection of the barrier width is based primarily on the species involved, the lateral size of the hardscape, and the soil environment. Protection of subterranean structures usually involves overfills of 31 inches (800mm) or greater. This volume of soil permits normal vegetation growth, while excluding roots from structure encroachment. Most installations require no alteration for soil hydrology i.e. the drain layer in landfills or next to foundation or walls. If diversion of water flow is required, a geomembrane is used in conjunction with Biobarrier e.g. under landfill toe drains. Some of typical applications are;

To Separate

  • Golf Course Greens
  • Planting Beds Tree Farms

To Redirect Roots

  • Curbs, Sidewalks, Roads, Median Planters

  • Bike/Golf Cart Paths, Golf Greens, Sand Traps, Fairways

  • Tennis Courts, Swimming Pools

    Building Foundations, Drain Lines, Septic Fields, Waste Landfill Caps and Drains, Utility Lines, Septic Fields, Burial Vaults, Earth Dams and Dikes

4.3.2. Surround Applications:

Surround applications utilize an envelope of root control Biobarrier® to isolate root- sensitive objects from root systems. Therefore, they normally have a minimal effect on the soil volume available for root nutrients. Biobarrier provides the unique advantage of serving as a root barrier without affecting the soil hydrology.

Biobarrier’s fabric construction offers easy contouring to fit any configuration. It can be readily cut with a knife or scissors. Because of its inhibition zone, root exclusion seams are obtained simply by overlapping or seaming. To resist the forces of soil shifting, seams can be permanently cemented using various adhesives (see seaming instructions).

Surround applications involve a wide variety of installation techniques. Sketches illustrating a few specific examples of how Biobarrier is applied are given below.

Drain Line/Septic Tank Installation


4.3.3. Combined Applications:

Combinations of these application categories are often used to meet multiple protection requirements. Biobarrier® readily lends itself to these more complex installations because of its flexibility, conformity and permeability characteristics; consequently, an effective, contiguous barrier of virtually any shape is possible.

To protect utility lines in a corridor, Biobarrier is positioned to confine the roots to the corridor, providing protection to the adjacent buildings and the roadway, as well as the four utility lines. This is accomplished without unduly restricting soil volume available for root system growth or altering soil hydrology.

4.3.4. Weed Control Applications:

Biobarrier® Pre-emergence Weed Control fabric is installed horizontally 2 inches (50 mm) beneath the surface for long-term weed control. Horizontal applications usually require flexible wide-width barriers capable of adjusting to soil shifts without damage. Biobarrier, utilizing a geotextile fabric, is designed for this purpose. Any required width can be obtained by overlapping the product or, preferably, hot-melt seaming.

When properly installed in weed control applications, Biobarrier limits soil available for weed roots to establish a viable root system. Trifluralin vapors migrate through the soil and into the cover material. Below a capped surface, the vapors are concentrated in cracks and crevices where unwanted vegetation would normally persist.

Features of Typar® Fabrics:

  • Porous 100% Polypropylene Nonwoven Construction Breathes
  • Moisture, Fertilizers, Air Reach Plants to Allow for Healthy Soil
  • Durable, Tear-Resistant; Won’t Rot or Mildew
  • Lightweight, Easy to Install, Follows Natural Ground Contours
  • Ideal for Use in Landscaped Beds, Under Decks and Walkways
  • Cover with 3-4″ of Mulch, Bark or Stone
  • 10 Year Guarantee If Installation Instructions Are Followed

Typical Examples:

  • Paver, Brick, Asphalt or Gravel Walkways, Planting Beds (Non- Food Ornamentals)
  • Parking Lots, Playgrounds and Utility Substations

4.4. Physical and Chemical Properties Biobarrier®:

  • Fibers used in the manufacture Biobarrier substrate fabric shall consist of long chain synthetic polyolefins (at least 95% by weight) and a UV stabilizer. They shall be formed into a stable network such that the filaments or yarns retain their dimensional stability relative to each other.
  • Nodules consisting of trifluralin, carbon black, and polyethylene compounded in a patented method utilizing time-released characteristics are permanently attached to the substrate fabric on 1-1/2″ centers by a through injection molding process.
  • All substrate property values, with the exception of apparent opening size (AOS), in these specifications represent minimum average roll values (MARV) in the weakest principal direction (i.e., average test results of any roll in a lot sampled for conformance or quality assurance testing shall meet or exceed the minimum values provided herein). Values for AOS represent maximum average roll values.
  • Biobarrier®: is a long-term root control system which utilizes time release of a herbicide. When properly installed, it prevents damage to hardscape and other areas from root intrusion. Effective life of Biobarrier is more than 15 years with exact life depending on specific installation conditions.

5. Tex-R® a patented technology for the control of roots and weeds:

Tex-R® technology features a needle punched nonwoven fabric coated on one side with SpinOut®, a long lasting coating containing copper hydroxide. This makes Texel the only North American manufacturer to offer a reliable solution that is both affordable and effective. In order to meet the needs of your production process, Texel has developed a complete range of products that take full advantage of Tex-R® technology for every horticultural application imaginable. You will reap extraordinary benefits:

• Lower overhead and lower labor costs for hand weeding.

• Optimized, controlled growth of plants and trees.

• Excellent results during transplanting and lower production losses.

5.1. Root Control Barrier:

Tex-R® Barrier™ is used to limit root growth within a predetermined area. Completely safe for the environment, Tex-R® Barrier™ fabric is perfect for urban locations and for any other application where protection against plant roots is important: foundations, golf courses, patios, retaining walls, and more. Tex-R® Barrier™ is amazingly effective.

• Improves the quality and durability of the planted area.

• Promotes development of secondary stabilizing roots.

• Is permeable to water and promotes nutrient absorption.

• Aids tree planting in urban areas or restricted spaces.

• Eliminates the need for solid root control structures.

• Reduces landscaping maintenance and repair costs.

• Easy, affordable installation & Provides an excellent return on your investment.

5.2. Root control barrier for Pot-in-Pot production: Inserted between growing obtainer and the socket pot, Tex-R® Insert™ reduces roots from emerging through the socket pot’s drainage holes. Tex-R® Insert™ is the ideal tool for optimizing your operations.

• Facilitates plant removal.

• Eliminates pot turning during plant removal.

• Protects vital roots during plant removal.

• Easily adaptable to a full range of containers.

• May also be used for propagation production

5.3. Root pruning fabric: Tex-R® Propagation™ is the perfect root pruning fabric for nursery propagation. It can be used in sand beds and under trays or containers. Tex-R® Propagation™ forces the plant to develop its vital root system within the growing device. No matter how you use it, Tex-R® Propagation™ guarantees the following benefits:

• Prevents root damage during plant removal.

• Limits damage to the plant.

• Reduces labor costs and Increases production quality.

• Installs easily & Available in standard width of 6 feet and in lengths from 50 to 328 feet. Additional dimensions available upon request.

6. Conclusion:

We can enjoy trees and benefit from them in the midst of our busy cities or wherever we play — on golf courses or amusement parks—and we can still prevent costly damage to our sidewalks or streets. We are the stewards of our environment, and ultimately bound to our forests and landscapes. As the keepers of trees, we must achieve quality in the administration of our responsibility to them. While comparing chemical control of roots and weeds, textiles are seem to be environment friendly and in this era of developing greens, textiles will have a wider scope in these applications.

• Golf Course Greens

• Planting Beds

Tree Farms

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Filed under Technical Textile

Application of Textiles in Car Interiors

INTRODUCTION

The importance of interior design to the potential sales volume of passenger car has always been a major consideration to the automobile stylist. However, despite the fact that textiles had for a long time played a part in automobile manufacture it was not until the early to mid- 1970s that these same companies began to realize the role that well-designed textile fabrics could play in the design of attractive interiors.

The reasons for this are:

  • Cars were largely designed by engineers, who although talented were not usually textile technologists and so they relied upon their suppliers to alert them to developments. They tended to develop tried and trusted products due probably then as now, to the huge ‘probability of getting it wrong’
  • The second reason was that up until this time the textile industry had not come to regard the automobile industry as a major market for aesthetically designed fabrics. This was due to problems with performance that the existing technologies struggled to produce products, which could withstand the critical requirements to abrasive wear and high light fastness. The products that could meet the criteria were usually unexciting fabrics, probably piece dyed, which offered little design potential.

Nowadays, car interiors are being influenced more than ever by consumers. They demand greater comfort- the seats should be comfortable and not cause excess fatigue, whilst noise from both inside and outside the car should be kept as low as possible. In addition, they want cars to be safe and environmentally friendly. They feel that the interior should be tasteful designed and that attempts should be made to reduce the car’s weight.

It is estimated that approximately 45 sq meter of textile material is used in the average car for interior trim, which includes:

  • Seating area
  • Headliners
  • Side panels
  • Carpets
  • Trunks
  • Door trim, Dash mat

Approximate breakdown of main textiles in an average modern car

Application area % share
Carpets(including Car Mats) 33.3
Upholstery(seating fabric) 18.0
Pre- assembled interior components 14.0
Tires 12.8
Safety-belts 8.8
Airbags 3.7
Others 9.7
Total 100

Average consumption of various visible automotive textile components per car

Components Small cars

Sq.m(g/m2)   wt.kg

Large cars

Sq.m(9g/m2)   wt.kg

Utility vehicles

Sq.m(g/m2)    wt.kg

Seat upholstery 5.0 (450)         2.25 6.0 (500)          3.00 8.0 (500)         4.00
Floor covering 4.0 (500)         2.00 6.0 (600)          3.60 9.0 (600)         5.40
Boot/bonnet liner/side panel 0.72 4.0 (720)          2.88
Roof-lining 1.5 (300)          0.45 2.5 (300)          0.75 3.2 (350)         1.12
Door panels 2.2 (400)          0.88 3.0 (400)          1.20 3.6 (400)         1.44
Seat belts 0.6 (250)          0.15 1.2 (350)          0.42
Total 6.45 13.80 14.25

Special Requirements for Auto-interiors

The common expectancy of the car user is that the auto-interior should have:

  • Good appearance and aesthetics
  • Good comfort
  • Easy to maintain
  • Retention of good properties even after prolonged usage
  • Good durability
  • Wrinkle resistance
  • Water and stain proof
  • Having antistatic and oil release property
  • No or minimum emission, which may hinder driving by fogging or contamination of inside atmosphere
  • Flame resistant for safety
  • Low costs

Processing requirements:

  • Mouldability
  • Susceptibility to compression
  • Sewability
  • Weldability
  • Adhesive properties
  • Vulcanizing properties

The main criteria involved in the development of textiles and components in automotive are:

  • Tensile strength
  • Abrasion resistance
  • Pill resistance
  • Air permeability
  • Compression resistance
  • Elasticity
  • Light fastness at high temperatures
  • Stiffness
  • Ease of cleaning
  • Separation force
  • Dimensional stability
  • Flame resistance
  • Fogging
  • Resistance to adverse climatic conditions

RAW MATERIAL USED FOR MANUFACTURE OF CAR INTERIORS

Various fibres used in automotive interiors and their properties

Application

Fibre used

Properties
Seat covers Nylon, polyester, polypropylene, wool Abrasion and UV resistance, attractive design and texture
Seat belts Polyester Tensile strength, extension(unto 25-30%), abrasion and UV resistance
Carpets Nylon, polyester, polypropylene Light fastness, mouldability
Airbags Nylon 6,6 and nylon 4,6 Resistance to high temperature inflation gases, durability to storage over many years, tear strength
Seat fire barriers Panox (UCF), Aramid(Nomex,Kevlar-DuPont),Inidex(Courtaulds)PBI(Hoechst) Very high FR including restrictions of heat release, toxicity and opacity of fumes
Door trim Polypropylene, nylon polyester
Trunk liners Polyester blends

Polyester and Polypropylene

Their relative merits are discussed below:

  • The two fibres are comparable in tensile strength though polyester fibre is available in higher tenacity grades.
  • Elongation is higher in polypropylene. This gives some advantages in terms of reduced tear during moulding.
  • Density of polypropylene (.91g/cc) is much lower than that of polyester (1.38g/cc). As a result thicker, loftier and more comfortable carpets are made with the former for a given area density.
  • Polypropylene is dope dyed and is available in an extensive range of colours and shades. It is therefore much easier to achieve colour and shade matching by mixing a minimum number of shades of fibers. Doped dyed polyester, on the other hand, is available only in a limited number of colours and shades.
  • Melting point of polypropylene (165˚C) is much lower than that of polyester (260˚C). Heating time, temperature and pressing time are therefore more critical in moulding with polypropylene.
  • Flame retardancy by burning rate is inferior with polypropylene than with polyester. A flame retardant compound has to be added to the binder to meet the flammability requirements in exports with polypropylene. This adds to the costs.
  • Resistance to UV light is inferior with polypropylene compared to polyester. UV stabilizer has to be added during manufacture of polypropylene to improve its resistance to UV light.
  • Polypropylene tends to form beads during carding. The beads get deeply loaded on the cylinder wire and also on the needles.
Jute

Jute nonwovens, commonly known as jute felt, either as cent percent natural or blended with other synthetic fibre have found various end uses in automobiles.

Advantages of jute nonwovens.

  • Fuel saving:

The decrease of a car weight by 1kg allows decreasing the fuel consumption 0.05 to 0.1litre per 100km. So the replacement of metallic parts by plastic based on natural fibre has an additional advantage of fuel saving.

·         Low thermal conductivity

The natural fibres also show low thermal conductivity and therefore considered a good heat barrier.

·         Competitive specific strength

The mechanical parameters of natural fibres can compete with glass in respect of specific strength.

APPLICATIONS:

  1. Nonwoven jute automotive Seat backing
  2. Nonwoven jute auto carpet under laying
  3. Nonwoven jute chemical bonded panels
  4. Short jute fibre based thermoplastic panel

Flock and Flock yarns

Flock in the car has several positive advantages:

  • Sorption of moisture
  • A feeling of comfort
  • Serviceability
  • Smoothness
  • Acoustic insulation
  • Easy-care properties

In flock production additives are added to a special polymer during spinning to improve various properties, the filaments then drawn to form a tow. This tow must be cut precisely.

For flock used in the car industry the staple length is 1mm and the linear density is 3.3dtex.

Synthetic Wood Pulp (SWP)

  • This material is produced by Mitsui Chemicals, Tokyo, Japan
  • These are polyethylene and polypropylene fibrides, which are gained directly after polymerization.
  • SWP has morphologic characterstics similar to natural cellulose, synthetic staple fibres and asbestos fibres.
  • In the automotive sector, SWP as binding fibre is more suitable than phenolic resins and PP fine fibres as regards the distribution properties and minor separation tendencies.
  • Compared with phenolic resins SWP creates less odorous annoyance.

The recycling conditions have been improved, which is becoming more and more imperative in the automotive industry.

FABRICS USED FOR PRODUCTION OF AUTO-INTERIORS

NONWOVENS

  • Nonwovens have better adhesion property than woven and so binder application is more uniform.
  • They also possess higher thickness for a given weight per unit length and so are more voluminous and comfortable.
  • In addition they have a more uniform, smooth and random surface.

As a result nonwovens are preferred for moulded carpets used in modern cars.

Nonwovens are used globally for the following applications:

  • Floor panels
  • Carpets
  • Boot linings
  • Wheel compartments
  • Parcel shelves
  • Linings for the side panels
  • Roof linings
  • Car seats
  • Filters
  • Acoustic insulation

Emergence of nonwovens in auto-interiors is helpful in following ways:

  • Improving cost-effectiveness
  • Redefining carpet value
  • Finding new filters
  • Preventing fogging
  • Working with contours
  • Easily customized
  • Attractive
  • Durable
  • Strength and weight
  • Abrasion resistance
  • Thermal protection
  • Flame resistance
  • Acoustic insulation
  • Air filtration

WARP KNITTED SPACER FABRICS

Spacer structures are knitted fabric constructions comprising two separate fabric webs which are joined together by spacer threads of varying rigidity. The spacer threads are generally made of PES or PA monofilament yarns. The threads of the dial and cylinder stitches are made of textured PE filament yarns. The threads of the dial and cylinder stitches are made of textured PE filament yarns, depending on their intended field of application. The degree of space or height between the two fabric faces is determined in the circular knitting machine by the setting of the dial height relative to the machine cylinder. Spacer fabric heights preset in this way can vary between 1.5 and 5.5mm.

Properties:

  • Soft handle
  • Spring comfort(determined by yarn count, number of stitches, construction and threading-up arrangement)
  • Air permeability
  • Task-oriented comfort behaviour
  • Transport of moisture
  • Thermal insulation
  • Refraction of light
  • Sorption of noise
  • Filtration
  • Requisite dimensional stability
  • Longitudinal and/or transverse elasticity on one or both sides
  • Plastic deformation
  • Fabric can be folded easily
  • Recyclable
End –use sector Product description Substrate height Production machine Gauge
Seat cushion; substitute for foam Spacer fabric with two compact surfaces 3-8mm RD6DPLM/12-3 E22
Lining sector, e.g. Doors, struts, back-rest linings, dashboard, sun-blinds etc. Spacer fabric with two compact surfaces for laminating with fabrics or films

Spacer fabric with a patterned or open-structured surface

3-6mm

3-6mm

RD6DPLM/12-3

RD7DPLM/12-3

E22

E22

Roof lining Spacer fabric with one patterned or open-structured surface 3-6mm RD6DPLM/12-3 and

RD7DPLM/12-3

E22
Sprayed-on mudguard protection for lorries and buses Open-structured on one side Nearly 10-12mm RD6DPLM/12-3 E16
Seat heating in spacer fabric Compact on both sides. Heating wire is incorporated during warp knitting RD6DPLM/12-3 E12-16
WARP-KNITTING NONWOVENS

Because of their structure and functional properties, warp-knitting nonwovens should be introduced here as materials suitable for use in cars. Web bonding by warp-knitting the nonwoven has been effected by stitch-needles in fibre stitches or with binding yarns.

All these facts lead to the following functional properties of warp-knitting nonwovens:

  • Smooth surface protecting against abrasion
  • Fibre pile with high fibre surface
  • Pressure-elastic vertical fibre parts
  • Large share of pores
  • Limited adjustability of strength and stability in machine and cross-direction.

MAN-MADE LEATHER

Kurary developed the man-made leather “clarion” in 1965 in Japan. It was the first successful manmade leather to be commercialized in the world. Man-made leather is a complex product generally with nonwoven fabric and polyurethane and its structure is quite similar to natural leather. Most man-made leathers use a special fibre, which finally gives a micro-fibre.

Manufacturing technology:

  • Special fibre spinning which finally produces a micro fiber: First a bicomponent fibre is produced, one of which is then extracted in the following process, and which then becomes a micro porous fibre or a bundle of microfibres (so called sea-island fibres). A suede type of material is produced from the later fibre. Microfibres with a fineness of 0.2-0.001 denier can be produced by controlling both polymer and spinning condition.

For achieving a web, cross web method is more popular than random webber method because of the high uniformity of its weight.

  • Nonwoven: The process of making highly entangled nonwovens from laid webs is carried out through needle punching instead of water-jet system because it helps in achieving enough entanglement in three directions. In the end, a smooth fabric surface and a high entanglement influences the quality of the product and its appearance, handling and physical properties. So this process is one of the most important processes for man-made leather especially when manufacturing the suede type.
  • Combining a micro porous polyurethane resin to nonwoven: This process is where PU resin is put into a space between the fibres of a nonwoven and coagulated, then filled with micro porous PU sponge, and before or after this, one fibre component is extracted to make bicomponent fibres into a micro porous fibre or a bundle of microfibres.
  • Finishing: A grain-type man-made leather is produced by a PU coating of the surface. A suede-type material is produced by buffing (napping) a raw substrate and dyeing and finishing it.

Characterstics of the manmade leather compared to natural leather

  • Uniformity
  • Washability
  • Wide colour range
  • Lightweight
  • Very good appearance, just like natural leather
  • High aesthetic properties such as softness, handling, touching, etc.

COMPOSITION OF INTERIOR TRIM IN SOME MODELS OF CARS

Model of

Car or vehicle

Insert

Bolster

Door pad

Seat

Sides

Headliner

Fabric supplier

A. MARUTI

800

FB

V

V

FB

PVC

FB

RELIANCE

800-DLX

FB

FB

FB

FB

FB

FB

MELBA

ESTEEM

FB

FB

FB

FB

FB

NWV

MELBA

ZEN

FB

V

V

FB

PVC

PVC

RELIANCE

OMNI

FB

V

V

FB

PVC

PVC

RELAIANCE

B.HONDA

CITY-STD

FB

V

FB

FB

PVC

PVC

SHAMKEN

CITY-DLX

FB

FB

FB

FB

FB

PVC

MELBA

C.DAEWOOD

CIELO

FB

FB

FB

FB

FB

PVC

RELIANCE

MATIZ-STD

FB

V

V

FB

PVC

NWV

MELBA

MATIZ-DLX

FB

FB

FB

FB

FB

NWV

MELBA

D.GEN. MOTORS

ASTRA OPEL

FB

FB

FB

FB

FBB

FB

FAZE3

E.FIAT

UNO

FB

V

V

FB

PVC

NWV

SHAMKEN

SIENA

FB

FB

FB

FB

FAZE3

F.TELCO

SUMO-DLX

FB

V

V

FB

PVC

FB

MELBA

SAFARI

FB

FB

FB

FB

FB

FB

MELBA

SIERRA

FB

V

V

FB

PVC

PVC

MELBA

INDICA-STD

FB

V

V

FB

PVC

PVC

MELBA

INDICA-DLX

FB

FB

FB

FB

FB

FB

MELBA

G.HYUNDAI

SANTRO-STD

FB

FB

V

FB

FB

PVC

FAZE3

SANTRO-DLX

FB

FB

FB

FB

FB

PVC

FAZE3

H.MISTUBISHI

LANCER

FB

FB

FB

FB

FB

NWV

FAZE3

I.FORD

ESCORT

FB

FB

FB

FB

FB

NWV

FAZE3

J.MAHINDRA

ARMADA

FB

V

V

FB

PVC

FB

RELIANCE

VOYAGER

FB

V

V

FB

PVC

PVC

C/R

K.HIND. MOTORS

AMBASSADOR

FB

V

V

FB

PVC

PVC

SHAMKEN

CONTESSA

FB

V

V

FB

PVC

PVC

RAYMOND

FB= fabric      V= vinyl     NWV= nonwoven fabrics

Textiles in Car

CAR INTERIOR COMPONENTS

SEAT COVERS

The most obvious area of application for the textiles in vehicles is in seating. At one time leather was used almost exclusively in these areas, exception cheaper cars where it was replaced by leather type materials. Leather is still the choice for the most luxurious cases, but the right grade of leather is now so expensive that it will clearly be limited to the market. The penetration of textiles into seat facing area is now virtually complete as the table shows:

Year 1979 1980 1981 1982 1983 1984
Percentage(%) 75 85 88 89 90 90

Evaluation points for auto-seat covers

  • Physical properties like Extensibility, tear.
  • Adhesion to backing (foam or nonwoven)
  • Effect of heat, light, moisture and chemicals on physical properties
  • Fastness properties of dyes used
  • Performance criteria (abrasion, pilling, flex)
  • Propensity to fog, odour, soil, static.
  • Fibre or colour migration to other textiles, which come in contact with it.
  • Special demands like flame proofness, thermal insulation, water proofness, sound dampening.

The type of fabric used for seating varies from location to location:

  • Both woven and knitted fabrics are used in Europe and USA. In USA, woven velour is preferred whereas in Western Europe, the car builders are favouring

Knitted fabrics.

  • In Asia, however the majority of the car seating fabrics is knitted.

In Japanese market, the car builders have always been favouring woven velour fabric and this trend looks unlikely to change

Seat comfort

Constructional guidelines for car seats with optimized comfort:

Covering

Textile fabric better than leather(natural or synthetic)

Velours better than flat woven better than flock

Part hygroscopic fibres better than 100% synthetics

Lining

Hygroscopic wadding (e.g.WO) better than foam pad

Cushion components

Spring core/rubberized hair pad better than foam pad

Cut foam better than molded foam pad

Perforation of foam pad

Seat cushion and back as thin as possible

Open frame

Design

Ventilation layer (spacer fabric) with/without forced air stream

If large side supports, grooves in seat cushion and back rest

The use of flat woven fabric is decreasing while the use of all-pile fabrics is decreasing. The dominant fibre used in car interiors is polyester. Nylon was used in early seat fabrics. Polypropylene is used successfully in accent colours and some bolster fabrics. Major yarn structures are flat continuous filament, false twist, air jet textured and knit-d-knit. Regularity of structure is of critical importance. Finishes such as lubricants and antistatics are applied to seat fabrics. After finishing, the fabric is laminated. Testing of seat fabric includes heat stability, light degradation and pile distortion. Ovens with temperature and humidity control are used for the tests.

Recently, Inland Fisher Guide, a components division of General motors, has developed a new technology for a seamless seat cover. Using 3D knitting integrated, three-dimensional seating fabric is produced while substantially reducing the need for cut-and-sew operations. Seating fabrics are becoming lighter, thinner and more contoured. The stretch is needed to maintain contours of the design.

Different fabric production methods are chosen as a means of analyses as each one results in a final fabric which has its own character, and reflects either an appearance, a handle aesthetic, a means of achieving design or just a struggle for a piece of objective.

CARPETS

There are about 3.5 to 4.5 sq mt carpet in each car. Apart from ethical and sensual comfort, carpets also play significant role in acoustic and vibration control.

Road noise is considered as an environmental pollution in few countries. There are pressures on automobiles to reduce external noise by about 50%(up to 3dB). Carpets are contributing to solve this problem. Carpets by providing thermal and acoustic protection thus directly contribute to safety.

Types of carpets

The carpets used in cars are mainly of three types:

  1. Tufted cut-pile
  2. Tufted loop-pile
  3. Needle-felt

The type of carpet used in car is mainly dependent by location. Needle-felt carpets are the most popular carpeting in cars made in Western Europe and Japan during 1980’s. It is predicted that finer gauge tufted carpets will be fitted in most of the European cars in near future. The same trend can be observed in Japanese market. In contrast, tufted carpets have always been preferred to the largest extent in US market. Americans never accepted needle felt carpets as floor covering and this trend does not appear to change. Contemporary carpets have good light fastness, soil and abrasion resistance.

Manufacturing process

  • Carpets are manufactured either by tufting or needle felting. Carpets made by tufting are based upon a supportive backing, which is used as a base to accept the pile yarns, which becomes the uppermost surface.
  • Carpet backing is usually spun bonded and is made by an integral process in which polymer chips are melted and filaments are extruded through a die. Mainly carpet is used in making thus carpet backing whereas a blend of nylon and polyester is used in some occasions and polypropylene in very few occasions. But during recent times polypropylene is assuming great importance considering the recyclability.
  • The process of needling has got the advantage of more productivity at relatively low cost. But carpets produced by needling cannot be used to cover sharp contours especially foot areas and transmission tunnels. Superior needled material has a good filling which is determined by the amount of vertically oriented fibres at a given stitch density.
  • Carpets and rugs can also be woven on the Loopile Master which is a double rapier weaving machine.
  • Generally, carpets are made by the combination of a variety of functional layers into a single unit and these types of carpets are very popular. A layer of adhesive is applied on these carpets during the initial stages to stiffen the whole carpet structure and in some cases specially formulated backing compounds are used to impart unique functional properties. A heavy mass layer that acts as soundproof is common to all automobile carpets. Carpet that has been finished is sent to moulding station where it is pressed to deep-draw mould to form it with appropriate dimensions. In European market viscoelastic polyurethane foam is used for backing while in American market, cotton fibre pad is used. The trend in USA is towards more moulded polyurethane foam due to its superior acoustical and physical properties.

Moulded carpet manufacturing can be divided into four sections:

  • Needle punching
  • Back coating of needle punched fleece with binder
  • Lamination, blank cutting and moulding
  • Trimming checking and packing

Trends in carpet development can be summarized as follows:

  • Use of PA BCF yarns in different versions for the tufting sector
  • Color concepts (multicolor)
  • Surface designs with specific associations (natural look, young style, fun , sporty, luxury etc.)
  • Improved feel (cosy, soft feel, velvety, luxurious, etc.)
  • Improved cleaning properties (placement of needle-punched nonwovens in the boot)
  • Optimized long-term utility
  • Finer gauges (tufting), liner fibres (needle punched nonwovens)

Noise control

Sound is propagated through the air and by vibration of the car body and there are three basic methods of reducing it:

  • By absorption
  • By damping
  • By isolation or insulation

In general a thick piece of material will absorb more sound than a thinner piece of the same material.

Sound absorbancy is influenced by:

  • Density of the material
  • Air porosity of the material
  • Thickness of the material

Carpet structure for noise control

Layer Materials used
Top decorative layer Tufted BCF nylon or needle-punched polyester or polypropylene-back, latex coated with SBR or acrylic latex.
Thermoforming layer Polyethylene powder, meldable fibres, EVA or a further thick layer of compounded SBR latex.
Acoustic layers ‘heavy layer’ of EPDM, shoddy fibres or polyurethane foam
DOOR AND SIDE PANELS

The following table will show the increasing use of textiles in door and side panels

Years 1979 1980 1981 1982 1983 1984 1985 1988
% of textile use 25 34 42 4 49 70 80 90

As in the other areas of the cars, the vehicle model very much dictates the fabric type used on door and side panels. The choice is dictated by cost considerations consistent with desired appearance and aesthetics. The fabrics used for doors etc should have high degree of stretchness. This can be obtained by incorporating elastomeric yarns into structure of fabrics.

Now a layer of foam is added to the door panel fabrics to get a more luxurious touch. Still development includes the utilization of high pile polyester fabric without distortion and to eliminate Vinyl backing.

HOOD FABRIC

The textile content consists of:

  • Inner hood
  • Hood upholstery
  • Cover fabric

The inner hood completely covers the hood frame and is produced from piece-dyed, profiled warp knit fabric which can be very efficiently processed, offering excellent crease reversibility.

The hood upholstery is a multilayer fabric, the nonwoven polyester fabric supported by a woven net fabric which absorbs tensile loads.(the cover fabric, the hood fabric, consists of two-layer woven PES and/or PES/PAC fabrics which are bonded by an elastic intermediate layer<rubberizing>). Spun-laid fabric layers on top and underneath largely eliminate running and activity noises. The upholstery wadding completely covers the frame to allow the hood arch to be laminated to the best effect.

HEADLINERS

At one time the headliner was simply a covering for the metal roof inside the car and consisted of a piece of fabric, PVC or same other material simply ‘slung’ i.e. held in place only at a few points.

From the table we can see that use of textiles in the form of circular knits and non woven fabrics is rapidly increasing while the use of PVC is rapidly decreasing.

Years 1979 1982 1984 1986 1988
Textile 16 33 48 60 80
PVC 84 67 52 40 20

Some important requirements of headliners are

  • Lightweight
  • Thin profile but rigid without any tendency to buckle
  • Flex or vibrates directional stability
  • Aesthetically pleasing
  • Soft in touch

The modern headliner is a multiple laminate of up to seven or more components all joined together. Each layer is there for a specific purpose either for aesthetics, to provide sound insulation, vibration clamping or to provide rigidity to the whole structure. The central layer is generally a layer of semi-rigid thermouldable polyurethane foam. This layer is bounded to two layers of chapped fibreglass roving, one on each side. The layers of glass roving help impart rigidity to the structure and noise reduction.

Attached to the side facing inwards is the decorative material, a nonwoven polyester scrim is usually attached to the other side. All layers are joined together by action of the hot-melt adhesives in a flatbed laminator, taking care neither to

damage the aesthetics of the decorative material nor to reduce the thickness of the center core.

TRUNK LINERS

Cars with trunk liners are making rapid gain in the headliner market. Now a days, the automobile manufacturers are making lining attached to the front and rear walls, in many cases attached to sidewalls also. This gives a most luxurious appearance and also serves as protection to both exterior walls and to trunk content such as luggages perfect to date.

The liners must be decorative and functional, yet have relative cost. These are usually made from waste fibre that are needled and then naturated with elastomerics materials. However, even spun bonded polypropylene is also used as a substrate for a foamed rubber material that is used as trunk liner.

Tests have shown that needle punched fabrics are better as compared to others because they have better wearing properties, cleaning easy and good resilience where floor covering application are concerned. Needle felt materials are also gaining importance rapidly as trunk lining.

LANDAU TOPS

Landau tops give the car an extra leathery look. The top of the car interior is generally covered with a nonwoven fabric. Now a days needle nonwoven is generally used. The process treats the needled polyester nonwoven with finishing materials to prevent wicking and rusting of the metal roof under the top. The extreme care is taken in handling the Landau top material to protect matter that would interfere with the subsequent dielectric sealing process used in assembly plants. Manufacturers are trying their best to make a fabric for top assembly having lightweight, good fastness or rubbing and also good-looking appearances.

PARCEL SHELVES

Parcel shelves, also referred to as package trays or the ‘hat rack’ are now almost invariably covered with needle-punched nonwoven mainly in polypropylene or polyester.

Parcel shelves range in size from relatively narrow components in saloon cars, to a much larger and wider article in hatchbacks.

Method of manufacturing

  • The textile-insertion low-pressure moulding method is sometimes used with a polypropylene covering to produce an all-polypropylene component. Polypropylene needle-punched fabrics used, are typically of 210g/m2 weight for flat components ranging up to 298g/m2 for more curvaceous designs, which require deep, draw moulding.
  • At present, however, the most traditional method of laminating the cover fabric to a rigid component made from shoddy (waste fibres) of wood fibre is still widely used.

DASHBOARD

The dashboard, probably the hottest area in the car interior, offers some opportunity for textiles, although a very limited number of car models use fabric at present in this very demanding application.

The dashboard shape being highly curved and also complex, to accommodate controls and instruments, presents many problems to the textile technologist.

It could probably only be obtained by knitting, and 3D knitting would be eminently suitable.

Performance criteria fulfilled by textiles are:

  • Low gloss (no glare or reflections on the windscreen),
  • Soft touch, pleasant aesthetics,
  • Non-fogging, non-odorous,
  • UV stability,
  • Resistance to heat ageing
  • Resistance to low temperature
  • High abrasion resistance

Cleanability would be limited but the ability to be thermoformed in mass production would be the most difficult problem to overcome.

SUNVISORS

In the USA, sunvisors are produced from raised –warp knit fabric, whereas in Europe PVC is still extensively used. Injection moulding produces some sunvisors, others are composed of metal frames and rigid foam or cardboard are also used. The article is close to the windscreen and UV light and heat resistance must be of the highest standard. Passenger safety is also an important consideration. There are opportunities for textiles, especially nonwovens in this area to produce a recyclable product.

SAFETY DEVICES

Car seat belts

The seat belt is an energy-absorbing device that is designed to keep the load imposed on a victim’s body during a crash down to survivable limits. Primarily it is designed to deliver non- recoverable extension to reduce the deceleration forces, which the body encounters in a crash. This non-recoverable extension is very important as it prevents occupants from being pulled back into their seats and sustains whiplash injuries soon after an impact. There is a play of not more than 30cm so that while the belt is comfortable to the occupants, it avoids impacts with windshield and other fixed parts.

In advanced car designs, seat belt works in coordination with the airbags. It holds the occupants in the correct position to strike the airbag when it is inflated.

Recent design of seat belt envisages inflatable seat belt. Weak stitching which bursts holds this belt when the belt inflates, giving four and a half times more area.

Requirements of seat belt:

  • Should be able to carry a static load of around 1500kg with a maximum extension of 25-30%;
  • Abrasion resistance
  • Heat resistance
  • Light resistance
  • Flexibility for ease of use

Specifications for manufacturing of seat belt:

  • Polyester (both doped dyed and yarn dyed) is the fibre mainly used in the seat belt manufacture
  • The yarns for seat belt are made of 320 ends, each of 1100dtex.
  • Warp direction is more critical since the force is applied in this direction during accidents.
  • Twill or satin weaves are employed for its construction. In this design long warp knuckles on both sides of the belt provide the necessary strength in the loading direction, lightweight and slim and flexible fabric with smooth surface, which gives comfort to wear and is easy to use.
  • Shuttle less weaving machines and high-speed needle looms are employed for weaving seat belts.
  • The woven fabric is shrunk by heat setting during finishing to improve energy absorption property. Shrinkage also increases weight from 50g/m to 60g/m.
  • The extension and reduced recovery from stretch properties are imparted to seat belts by controlled heat relaxation during finishing.

AIR BAGS

The increasingly stringent legislation and growing public awareness of the danger of motor accidents have forced car manufactures to put a greater emphasis in safety products like airbags, which cushions the occupants in the event of accident. Airbags provide protection against head-on collision. It is a high precision application, which on sensing a collision inflates within 0.125 seconds. In a collision the airbag begins to fill within 0.03 seconds by 0.06 seconds the airbag is fully inflated and cushions the occupant from impact. The entire event from initial impact to full deployment takes about 55 milliseconds. The use of safety devices such as airbags in combination with seat belts has reduced collision deaths by 28% and serious injuries by 29%.

Requirements of airbag fibres:

  • High strength
  • Heat stability
  • Good ageing characterstics
  • Coating
  • Adhesion
  • Functionality at extreme hot and cold conditions
  • Tear strength
  • Toughness
  • Fog resistance
  • Softness for reduced skin abrasion

Specifications for manufacture of airbags:

  • Nylon-6,6 and Nylon-4,6 are mainly used in the manufacture of airbag.
  • Silicone- coated airbags are preferred to neoprene coated bags due to:
    • Extended service life
    • Adaptation to rough duty vehicles
    • Reduced module size
    • Improved recyclability
    • Reducing cost
  • Due to high density of warp and weft symmetrical construction of the fabric and the need for constant air permeability across the width of the fabric, good weaving machines are required.
  • Rapier weaving machines excellent for production of airbag fabrics.
  • Water-jet and air-jet machines are also used.
  • Most of the silicone elastomer coated airbags are produced from a sophisticated woven construction of fabric at around 150 g/sq.m, coated with approximately 70-80g/sq.m of silicone elastomer.
  • The coating is applied as a single coat of the fabric by blade coating technique and polymerized in the oven under controlled tension conditions at a predetermined time/temperature.

Future application of automotive fabrics

  • Listings: Listings are strips of fabrics used to attach upholstery to the frame or moulded seat composite. These are interfaces that must be strong, have ample seam strength and low seam slippage, and must be able to hold a metal fastener or staple.
  • Insulator pads: Insulator pads are composites that act as a buffer between the foundation and upholstery.
  • Map pocket liner: Map pocket liner is a backing that supports the trim fabric.
  • Tie downs: Tie downs are fabrics attached to an extended olefin polymer bead. These are similar to listings in that they are used to attach upholstery to the frame assembly. Tie downs are specially items that are sold for specific applications.

CONCLUSION

It is well known that change is the only permanent thing in nature. Textiles are now reinvigorating discoveries and innovations in almost every area of economy, which are revolutionary, not the evolutionary. Increasing global competition has forced automobile manufacturers to look for ‘versatile’ fabrics. Automotive textiles are constantly evolving to meet the latest demands of car manufacturers. So surely the road ahead for automotive textiles will conquer the demanding market of automobiles.

Also in India the automobile engineering is in good march. Many foreign companies are setting their industries in India. Some of the automotive textiles are imported from foreign countries to India. It is better to incorporate those techniques in India for  better cost effectiveness.

It won’t be an exaggeration to predict these textiles to be the textiles of the 21st century.

REFERENCES

  1. Man-Made Textiles in India, March 2000, Pg 99-112
  2. Man-Made Textiles in India, March 2000, Pg 119-125
  3. Man-Made Textiles in India, March 2000, Pg 113-118
  4. Man-Made Textiles in India, March 2000, Pg 144-146
  5. Man-Made Textiles in India, March 2000, Pg 147-152
  6. Melliand International, Vol.6, June 2000, Pg 137-138
  7. Melliand International, Vol.6, Sep 2000, Pg 226-228
  8. Asian Textile Journal, Nov-Dec 2003, Pg 61-69
  9. Asian Textile Journal, Apr 2004, Pg 55-61

10.  Asian Textile Journal, Jan 2003, Pg 42-49

11.  Technical Textiles, Vol.42, Apr 1999, Pg E27

12.  Technical Textiles, Vol.42, Aug 1999, Pg E43-E46

13.  Technical Textiles, Vol.43, Mar 2000, Pg E11-E15

14.  Technical Textiles, Vol.43, Aug 2000, Pg E46-E47

15.  Technical Textiles, Vol.41, Feb 1998, Pg E4-E8

16.  Textile Asia, June 2003, Pg 72-73

17.  Knitting Technique, 14(1992) 2, Pg106-109

18.  Knitting Technique, 16(1994) 3, Pg161-162

19.  Knitting Technology, 1/1999, Pg 24-25

20.  Knitting Technology, 20(1998) 2, Pg 54-57

21.  Knitting Technology, 18(1996) 2, Pg 71-73

22.  The Indian Textile Journal, June 2003, Pg 13-19

23.  TM, Issue2, 2004, Pg 32-34

24.  TUT N°35. 1st Quarter 2000, Pg 19-20

25.  TUT N°35. 1st Quarter 2000, Pg 35-39

26.  TUT N°41. 3rd Quarter 2000, Pg 55-56

27.  Kettenwirk-praxis, 3/95, Pg E28-E29

28.  Textiles in Automotive Engineering, By-Walter Fung and Mike Hardcastle

29.  www.tx.ncsu.edu/ci/automotive/index.cfm

30.  www.textilefiberspace.com

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