Some Thoughts and Information on Nonflammable Products

Journal of the American Association of Textile Chemists and Colorists January 1972/ Vol. 4, No.1 ((X)

Some Thoughts and Information On Nonflammable Products

By ERNEST R. KASWELL, Fabric Research Laboratories, Dedham, Mass.

N December 14, 1967, President position that I, as a textile technolo- O Johnson signed into law a new gist and as a citizen, take concerning Flammable Fabrics Act. Its purpose this controversial Flammable Fabrics was "to amend the Act to increase the Act. protection afforded consumers against The first part of my address will injurious flammable fabrics." The Act deal with the problem, and the actions ABSTRACT became law one year later, and since which I believe our industry properly December 1968 the textile, apparel should take, and eventually must take, This paper recognizes the need for and home furnishings industries have probably by Government fiat if they fabrics that are less flammable and been in ferment about its significance, do not come voluntarily, in develop- describes criteria normally employed to particularly with respect to the need ing safer textiles. evaluate flammability characteristics- for and establishment of new or re- The second part of my talk is more ease of ignition, rate of burning, ease vised test methods and standards of technical and recounts some of the of extinguishment, types and amounts of smoke and toxic gas generation, flammability, and their ability to meet studies in which my associates and I thermal shrinkage, thermal insulation such standards with their present tex- have been engaged in the development ability, and integrity of material at and tile products. Moreover, the industry of some of the newer protective, fire- during the time of heat and fire is concerned about its future technical resisting materials. Most of this work exposure. and economic abilities to produce less has been sponsored by the Air Force flammable and thus less hazardous Materials Laboratory, the NASA Fire-resisting properties of Nomex, fabrics. Durette, Fypro, FRL-T-fibers, Kynol and Manned Spacecraft Center, 'and the PBI fiber are reviewed, and the Those of you here today who are U.S. Army Natick Laboratories. The performances of some of them exposed active in the textile industry surely objectives of such work are to produce in garment form to a burning jet fuel need not be reminded of the plethora materials which give better fire pro- fire are reported. Regular and modified of technical and trade meetings, sym- tection to military personnel and to the PBI fabrics and the modified aromatic posia, workshops, hearings, papers and astronauts. One by-product of such polyamide fabrics are reported to show policy statements made by people in research, which all of you as taxpay- great promise for use in protective our industry relative to the Flammable ers sponsor, should be the utilization clothing. Their potential for general Fabrics Act. In fact, tomorrow at this of such information and materials in apparel and home furnishings is also considered. Golden Jubilee Conference four timely improved consumer goods to protect papers on the subject will be pre- all people against unnecessary fire sented. Therefore, my initial remarks risks. KEY TERMS probably present nothing new to my Consumerism knowledgeable colleagues regarding Greater Consumer Protection Fire Resistant Fibers the flammability problems that the Flammability textile industry has been facing in the It seems clear to me that both the Nonflammable Fibers past three years. U.S. Government, and many indivi- Organic Polymers However, part of my audience to- dual state governments, are rapidly Oxygen Index day is not necessarily technical, and moving in the direction of greater con- Polymers so I would like to tell them some of sumer protection. I think we all like my thoughts on the subject and the the philosophy of consumerism, pro-

1/33 Olney Medal Address vice that they get from the TV re- once ignited burns rapidly and catas- pairman. trophically, and which consequently Nonflammable Products If you stop to think about it, there's was outlawed in the early 1930's. Our a little bit of solace in this reciprocal long term goal should be the develop- retribution. It reminds me of a cartoon ment of essentially nonflammable ap- in a recent issue of the New Yorker. parel and home furnishings, but which A lady seated in her car is asked by have all of the other attributes that the service manager at the local gar- we as consumers want: attractive ap- age, "Do you want our usual, incom- pearance, a wide range of colors, com- petent, sloppy engine tune-up, or do fort, proper performance, durability you want our Ralph Nader Special?" and low cost. vided it's in somebody else's area and Why Not Fire-Safe Textiles? 10,000Deaths A Year not in ours. All of us are for Truth in Lending, or Truth in Packaging. I If we as consumers want other prod- U.S. Public Health statistics (1) show that in the U.S. there are about don't like to buy a box of tea bags ucts to be reliable and safe, why not containing 8.8 ounces. As a consumer fire-safe textiles? 10,000 deaths per year due to burns I want to be protected so that when I The case can be made for the need and thermal injuries. This is at a rate buy that television set I have a war- for a proper, reasonable fabric flam- of about 5 deaths per 100,000 popu- ranty that is reasonable, equitable and lation. The frequency of burn injuries mability law properly implemented, has been estimated at about 2 million contains no weasel words. and intelligently controlled, for here You as a consumer expect the auto- we are not talking about consumerism per year, resulting in the hospitaliza- mobile that you buy to be a safe, re- as it influences only our comfort and tion of about 100,000 people. Now liable vehicle, reasonably free from pocketbook. Here there is the very maybe these are not high rates, and I major and minor defects. If it doesn't vital point of product safety, and this am not saying that all of these burn meet these standards, you want pres- surely transcends most other consumer accidents resulted directly from the sure put on, by government if neces- demands. flammability of textiles. Nevertheless, no matter how small the rate and the sary, to get what you believe is coming Now I know the philosophy and absolute number of burns and deaths, to you. Perhaps (nay, hopefully) that position of many of our perfectly re- TV repairman and his wife are just spectable, ethical textile scientists and we must take every means at our dis- as aggravated at the inept, incompe- posal to try to reduce or eliminate engineers who feel that the Flammable them. tent, indifferent and expensive service Fabrics Act, and particularly the new rendered by the automobile dealer who standards that have been promulgated, Concomitant with the passing of the serviced their car as are the auto dealer for example for children's sleepwear, amended Flammable Fabrics Act, an and his wife who are exasperated at is an unnecessary harrassment to an organization was created with which the same kind of unsatisfactory ser- industry that already has plenty of most of my technical colleagues are trouble trying to get along in the well acquainted: the Information United States. The contention is made Council on Fabric Flammability. All that many of the proposed new stand- persons and organizations interested ards are ridiculous, impractical, un- in reducing the hazards of flammable necessary and expensive; that, con- fabrics are eligible for membership, sidering our population, only a rela- and most of our textile companies tively few textile fire injuries and fa- belong to it. Its purpose is: "to work talities occur each year and therefore for the reduction of morbidity and there is little need for improvement in mortality from burns caused by flam- the flame-resisting characteristics of mable fabrics and related materials, clothing and home furnishings, assum- by encouraging the exchange and dis- semination of all pertinent technical ing that the most dangerous articles, information. " like those notorious brushed rayon sweaters, are kept off the market. Unfortunately, most of the textile The Cure Is Prevention materials that we use in our everyday activities will burn. From a practical, Dr. George Crikelair, professor of economic viewpoint we obviously can- surgery at Columbia Presbyterian not rule out all such materials as being Medical Center, is one of the founders hazardous or dangerous. We all know of the council. In an article (2) en- that most of the apparel and home fur- titled "Medical Aspects of Clothing nishings that we buy are reasonably Burns," he states: safe, but this is because they are rarely "A burn is a most unpleasant ex- exposed to fire. The homemaker by perience. We doctors see too many of experience, education and intuition them. We cannot get the severely knows that her ruffled curtains will burned patients to survive. We earn burn if exposed to flame, and she sees good incomes by caring for these pa- to it they are not so exposed. In public tients. We are anxious to lose this buildings we all demand, and the law business. The greatest advances in requires, that decorative materials be medicine have been through preven- Ernest R. Kaswell, the twenty-eighth re- fire resistant in order to eliminate this tion. Think only about smallpox, cipient of the Olney Medal, AATCC's kind of public hazard. diphtheria and poliomyelitis. The cure highest recognition for technical and Cotton is an example of a widely for massive burns is in prevention. scientific contributions to textile chem- used apparel fiber which can burn, "The problem strikes us medically istry, is president and a founder of Fabric Research Laboratories in Ded- and yet millions of men wear cotton because clothing burns most often are ham, Mass. A past president of AATCC undershirts and dress shirts every day severe in extent and depth, and the (1963-64)and a native of Boston, he has without any serious concern that they morbidity and mortality rates are so been a frequent contributor to textile are endangering themselves. On the high. The most common cause of technology literature for more than 30 other hand, none of us now wears burns in children is the scald from hot years. shirts made out of nitrate rayon, which liquids. The most lethal in children

34/2 OX!Vol. 4, No.1 of ,all ages is the clothing burn. It has aggregation. We have X-rays and pol- serious attention to fabric burning been customary in rebutting the argu- arized light, and ultracentrifuges with rates. With carbon-base organic fibers, ment that clothing is the cause of the which to study them. There are quite a temperatures inevitably can be reached burn to state that the gas stove or the few thousand men in the world cap- where ignition in air will take place. match that ignites the fabric is really able of constructive thinking. If we Then the rate of burning becomes im- at fault, that the child's running in- cannot beat a silkworm, I am ashamed portant. stead of dropping and rolling after the of the human race." Most people recognize that, once clothing ignites, have all created false Precisely at the time Bush made ignited, cellulosic fabrics can burn factors in the clothing burn, that it is these remarks, Wallace Carruthers was fairly rapidly unless they are treated flammable liquid that causes the burn in the midst of his polymer research at with fire-retarding chemicals. In com- and not the burning clothing." Harvard, and then at The Du Pont parison, wool textiles intrinsically have He goes on to state, "Whatever the Co., doing just what Van Bush en- much better flame resistance and a ignition cause, doctors agree clothing visaged. Nylon resulted in 1938. So I lower burning rate. I'm sure most peo- burns are severe, often fatal, and if say that if man can't come up with ple who smoke recognize that a burn- the clothing did not burn, the mor- fibrous materials that will be less flam- ing cigarette or pipe tobacco ember bidity and mortalities would be largely mable and with all the other requisite falling on a wool jacket is not con- eliminated. We must recognize that properties, we too should be ashamed sidered particularly dangerous. Even people are people. Children do run if of our even better-trained scientists. where the fabric starts to burn, its rate their clothing catches fire. They are is so slow that the fire can easily be frightened and hurt. Stoves, matches EvaluatingFlammability tamped out. and flammable fluids are here to stay, I cite these two classes of fibers and there will be accidents. Despite Among the criteria normally em- only to demonstrate that most people untold money and time spent on burn ployed to evaluate the flammability have a reasonable, logical ability to research, medically we seem to have characteristics of materials are: ease judge two different degrees of flam- reached a plateau on the survival of of ignition, rate of burning, ease of mability risk. We ought to be able to the severely burned patient. Since so extinguishment, types and amounts of establish rational maximum burn rates many of these burns are caused by smoke and toxic gas generation, ther- for specific garments and furnishings. burning clothing, the medical profes- mal shrinkage, thermal insulation The large and comprehensive fabric sion votes for prevention of these ability, and integrity of the material at flammability study being conducted at burns by encouraging the furtherance and during the time of heat and fire the National Bureau of Standards of flame-retardant clothing." exposure (4,5). should produce quantitative burning rate data. Attempts then should be made to correlate them with minimum Scare Tactics Ease Of Ignition acceptable performance levels in gar- In some of the technical symposia Ease of ignition is of major signifi- ments and home furnishings. Ultimate- that our textile technology fraternity cance, particularly for young children, ly there must be reasonable subjective has held in the last four or five years housewives and older persons, all of judgments made of the maximum there has been talk about scare tactics, whom may be accidentally exposed to burning rate permitted in a dress or particularly the presentation by con- direct flame or heat. If materials are sweater or other garment in order that cerned physicians of pictures showing difficult or impossible to ignite, or if the wearer may be protected against some horrible cases of burned people. they immediately self extinguish on unreasonable fire risk. Government And they are horrible to look at; one removal of the ignition source, then and industry should co-operate in the experiences the greatest feeling of one need not worry about all of the establishment of such standards. compassion for those who have been other problems of burning rates, noxi- so afflicted. These are the reasons why ous gases or heat transfer properties. High TemperatureResistingFibers we must do everything within our It should be apparent, therefore, power to prevent such catastrophes. that a target objective in the develop- During the GOLDENSCIENTIFICDE- The textile industry and the textile ment of fire or flame-resistant materi- CADEOF THE 1960's, much research technologist no longer can say, "But als is their ability to withstand igni- effort and money were expended in burn accidents are so few that we tion in the first place. Here both the developing high temperature and fire need not pay any attention to them. intrinsic characteristics of the fiber or resisting flexible fibers. A good part We need not worry about fibers and polymer as well as the geometric state of this work was sponsored by the De- fabrics that burn." of aggregation of fibers, yarns, fabrics partment of Defense and NASA. I say we do need to pay attention to and garments are of obvious impor- Table I shows a list of high tempera- them. Textile technologists and the tance. ture resisting fibers, most of which textile industry are smart enough to be Textile materials, because they must also have excellent fire resistance. able to solve these problems and pro- be flexible, are necessarily made up of Fig. I shows a plot of strength reduce clothing and home furnishings a large number of individual fibers of tention vs. temperature for some of the that will have proper flame resistance very small diameter. Thus the fiber new materials that have come upon in addition to all of the other attri- surface-to-volume ratio is very high, the scene. Using as a benchmark a butes that people want. and the opportunity for easy ignition strength retention of 40 per cent~ it I am reminded of what Vannevar and rapid combustion is proportion- can be seen that regular nylon has a Bush, the former vice-president of ately high. temperature capability of about 450F; MIT and one of the most famous It is vital that present polymers be Nomex, an aromatic polyamide, about engineers of our time, said back in the modified or new fibers developed 550; polybenzimidazole, a new fiber early 30's about the potential for syn- which are intrinsically difficult and in about which I'll have much to say in a thetic fibers (3). Now remember that the practical sense impossible to ig- few minutes, about 725; E-glass fiber the time was 1932 and the only man- nite. Later on I will show you some about 925; carbon fiber about 950; made fibers we then had were the re- data on ignition temperatures and and so on up through the superalloys generated rayons. Bush said, "Will we times for several new textile materials. and refractory metals, which may have ever make better fibers than nature thermal durabilities up to about in place of what we may call, with due 2000F. For ordinary or even protec- apologies to the hard-working organic Rate Of Burning tive clothing, carbon, glass, refractory chemists, our present weak imitations? Until we achieve reasonable success or superalloy metal fibers are either Well, there are 100,000 or so known in developing textiles that ignite only too heavy or brittle, or both. There- organic compounds, with all sorts of with great difficulty or not at all, or fore, these materials cannot, at the combinations and states of physical are self-extinguishing, we must give present time, be given serious consid-

January 1972 CO) 3/35 100 Olney Medal Address ;j ~80 NonflammableProducts I ~I- I i::i60 l- II!' II: :1:40 I- C) i::i II: 20 eration for use in consumer products l- even if their costs were low. V! O~ 0 250 500 750 1000 1250 1500 1750 2000 Organic Polymers Promising TEMPERATURE (OF) Some of the organic polymers, how- Fig. I-Strength retention versus temperature. ever, are most promising. Among these I shall discuss Nomex, Du Pont's aromatic nylon; Durette and Fypro, modi- ernment-owned pilot plant; and certain nation is made by holding a vertically fied aromatic polyamides produced by proprietary modified aromatic polya- oriented fabric test specimen against Monsanto and Travis Mills, respec- mides and PBl's developed by my col- a Calrod type heater, to which a ther- tively; Kynol, Carborundum's pheno- leagues at Fabric Research Labora- mocouple has been bonded, and then lic base fiber; polybenzimidazole tories. increasing the electrical power and (PBI), developed by the Air Force I In showing you some of the prop- hence the temperature of the heater and currently being manufactured by erties of these new candidate fire-re- until the fabric ignites. The tempera- the Celanese Research Co. on a gov- sisting materials, I will also give you ture of the surface of the heater at counterpart information on untreated the instant of initiation of burning is cotton and fire-resisting treated cotton the approximate fabric fire point. The for comparison. number of seconds of contact with the Table I-Candidate High Tempera- The flammability characteristics of Calrod unit to produce ignition is re- ture-Fire Resisting Fibers textile fabrics are functions of both corded as "time for ignition." Polymeric intrinsic fiber properties and yarn and Table II lists air ignition tempera- Aromatic Polyamides: Nomex (Du Pont); fabric structure. (Garment desigri-also tures and times for a rational series of , X-101 (Monsanto) deserves equal consideration.) There- test fabrics. Each block in the table Polybenzimidazole: (PSI) (Air Force) Polyoxad iazole fore, in our work we attempted to states that ignition did not (No) or Polyimide: PRD-14 (Du Pont) hold all geometric parameters con- did (Yes) occur. The number of sec- Poly dihydro dioxo bis benzimidazo benzo phenanthroline stant, developing and testing, wherever onds of exposure time of the specimen Phenolic: Kynol (Carborundum) possible, fabrics of the same fiber and against the Calrod is listed underneath. Modified POlyamides: Durette (Monsan- to); Fypro (Travis Mills); Aromatic T yarn size, threads per inch, thickness, For example, at 1500F the natural un- (Fabric Research) weight, weave, etc. dyed Nomex did not ignite after 40 Modified POlybenzimidazole: PSI-S (Fabric Research); PSI-T (Fabric With respect to thermal fire criteria, seconds of exposure; at 1450F the Research) the following properties were meas- No/Yes indicates that two specimens Glass ured: (I) Ignition temperature and did not and one did ignite after 40 E-Glass time. (2) Burning rate. (3) Thermal seconds of exposure; at 1600F the No- AF-S994 special glass Quartz shrinkage. (4) Thermal conductivity. mex ignited in one second. Untreated Carbonaceous Residue (5) Heat transfer characteristics upon cotton, as a benchmark, ignites im- Ca rbon flame impingement. (6) Special fire mediately at approximately lOOOF. Graphite pit testing of mannekins clothed with From the table one can see that Metallic experimental garments; the tests were some of these new exotic materials Stainless steel conducted at the U.S. Army Natick have remarkably high ignition tem- Superalloy Laboratories fire pit test facility. Refractory-whiskers peratures. Table III summarizes igni- Alumina tion temperatures where contact times Zirconiz Ignition Temperature And T'ime do not exceed 8 seconds. PBI, particu- Boron The ignition temperature determi- larly, shows promise, not only because

Table II-Fabric Ignition Temperatures (In Air at 14.7PSIA)

Fabric Calrod Temperature of Weight (Oz/Yd2) 1400 1450 1500 1550 1600 1650 1700 1800 Untreated Cotton 4.5 Ignites Immediately At About lOOOF FR Treated Cotton 4.5 No No Yes 120 See 90 See 1 See Dyed Nomex 5.0 No No/Yes Yes Yes Yes 60 See 60 See 5 See 5 See 5 See Natural Nomex 6.5 No No/Yes Yes 40 See 40 See 1 See Kynol 7.0 No Yes Yes Yes 60 See 7 See 3 See 2 See Fypro 4.3 No No/Yes Yes 60 See 60 See 1 See Durette 4.7 No Yes 30 See 25 See PSI 5.4 No Yes No 300 See 120 See PSI 4.8 300 See Yes Yes No Yes 6 See 3 See PSI-S 6.0 30 See 2 See

36/4 ceo Vol. 4, No.1 I

Table III-Fabric Ignition Tempera- Table IV-Limiting Oxygen Index Table V-Effect of Fabric Weight on ture Ranges Values for Spun Fabric LOI Values (In Air at 14.7 PSIA) (From Tesoro and Meiser7) (From Miller and Meiser8) Ignition Weight Weight Weight Temperature Fabric (OZ/Yd2) LOI (OZ/Yd2) LOI (OZ/Yd2) (OF) Acrilan 6.5 18.2 Cotton Sheeting 4.2 18.2 Untreated Cotton 4.5 -1000 Arnel Triacetate 6.5 18.4 8.2 18.5 4.5 1500 FR Treated Cotton Acetate 6.5 18.6 12.5 18.8 Dyed Nomex 5.0 1450-1500 Polypropylene 6.5 18.6 Natural Nomex 6.5 1550-1600 Wool Felt 2.5 23.0 Vinylon (PVA) 6.5 19.7 23.3 Kynol 7.0 1450 5.0 Rayon 6.5 19.7 7.5 23.7 Fypro 4.3 1550-1600 Cotton (Greige) 6.5 20.1 3.0 19.4 Durette 4.7 1650 Nylon 6.5 20.1 POlyester Felt (Pressed) 6.0 19.9 PBI 5.4 1700+ Polyester 6.5 20.6 9.0 20.9 PBI 4.8 1700 Wool (Drycleaned) 7.0 25.2 PBI-S 6.0 1650 Dynel 6.5 26.7 Nylon Fabric 6.5 20.1 Nomex N-4274 4.8 28.2 8.6 21.2 Phovyl(PVC) 55 6.5 37.1 14.4 23.5

of its excellent ignition resistance, but burn or to self extinguish, once the drops a lighted match on his clothing. because it also appears to have out- ignition source is removed. If all of us had high ignition tempera- standing textile qualities in terms of Table IV lists LOI's of commercial ture-high LOI clothing, much of the fabric hand, drape, comfort and phy- fabrics as measured by Tesoro and fabric flammability hazard would be sical properties. Meiser (7). Using 21 % of the line of eliminated. Two other methods of ignition were demarcation, one can easily assess the A more serious problem exists, how- also investigated: (1) a standardized relative rankings of the various fibers. ever, when the ignition source is not sample of burning facial tissue, with Miller and Meiser (8) show in quickly removed-for example, in a a burning time of 3 seconds; and (2) Table V that LOI's are almost inde- house or factory or aircraft fire where a propane torch, with a burning time pendent of fabric weight within con- other burning materials are serving as of 10 seconds. The conclusions drawn ventional ranges. There is a slight fuel. Here fabrics with high ignition from these direct flame tests essen- trend upward with weight increase. temperatures and high LOI's can be of tially corroborated the Calrod results. The LOI thus appears to be a valid great advantage in terms of protecting For conventional apparel and home criterion of the intrinsic flammability the body, provided that they are ther- furnishings we probably do not need of the fiber, essentially unaffected by mally stable and do not shrink, and the ignition resistance of a PBI. lam yarn and fabric geometry within con- that they maintain their structural in- not sure that we really know what the ventional fabric weight ranges. tegrity and do not become brittle or maximum contact time-minimum tem- Table VI lists LOI's for our new friable such that body movements will perature relationship should be to candidate materials. Their advantages cause them to split apart and fail. achieve fire-safe products. In at least appear obvious. one government standard, the time of Assuming that a fabric has a high Thermal Shrinkage contact of the open flame to the test ignition temperature and a high LOI (the two are obviously interrelated), Many textile fabrics, when exposed specimen is stipulated to be one sec- to temperatures approaching their ond. To me this is not only improper are these not enough to make the it is absurd. fabric fire safe? melting or decomposition points, will Shrink severely. Such shrinkage can For conventional clothing or home cause the garment to pull tighter over furnishings, the answer is probably Fabric Burning Rates "Yes." Assume that such fabrics acci- a person's skin surface. The insulating layer of air between the skin and fabric A pertinent related criterion is the dentally come into contact with a di- is reduced or eliminated, the heat tendency of the fabric, once ignited, to rect flame for a relatively short period transfer increases significantly, and a of time, say 3 to 10 seconds, and then much more severe skin burn can re- continue to burn even after the igni- the flame is removed. If the fabrics tion source is removed. Here another sult, even if the fabric doesn't ignite. recently developed test method, origi- ignite at all, they will probably im- Wherever people are exposed to the nally proposed by Fenimore and Mar- mediately self extinguish. This can be dangers of direct flame or high heat tin (6), can be employed. This is the kind of situation that pertains fluxes, it is important that their gar- called the Limiting Oxygen Index when one accidentally brushes a sleeve ments do not shrink thermally and that (LOI) and is defined as the minimum against a gas burner or candle, or fabric integrity is maintained. Where concentration of oxygen in a slowly there is sufficient thermal insulation rising mixture of oxygen and nitrogen and little or no thermal shrinkage, the that will just support sustained com- protection given the person is greatly bustion of the material. Since the per- Table VI-Limiting Oxygen Indices increased. Figs. 2 and 3 show two centage of oxygen in air at standard of High PerformanceFabrics Air Force flight suits that were ex- conditions is about 21 %, it is apparent Weil!:ht LOI posed to a jet fuel fire at the U.S. that materials which continue to burn Fabric (OZ/Yd2) (% Od Army Natick Laboratories fire pit test freely in air have LOI values less Untreated Cotton 4.5 16-17 facility. In Fig. 2 the garment has than 21 %. Cotton fabrics, for ex- FR Treated Cotton 4.5 31-32 shrunk, pulling tightly over the man- Natural Nomex 6.5 27-28 nekin's body. In Fig. 3 the fabric did ample have LOI's in the range of 17 to 5.0 25-27 20 %. Reduce the level of O2 below Dyed Nomex not shrink significantly, and has es- 17 % and the cotton will not continue Kynol 7.0 29-30 Fypro 4.3 29-30 sentially retained the same configura- to burn, once the ignition source is Durette 4.7 35-38 tion as it had prior to fire exposure. removed. PBI 5.4 38-43 Its advantage is obvious. The LOI thus becomes an excellent PBI.S 6.0 42-49 Fig. 4 plots fabric shrinkage as a criterion for evaluating the propensity Nomex-T 6.5 42-52 function of exposure temperature. At of a fabric, once ignited by an ex- PBI.T 6.0 65-75 temperatures above 800F the Nomex ternal source, either to continue to fabric was badly charred and curled,

January 1972 0::0 5/37 Fig. 2-PSI suit exposed to fire test. Fig. 3-Stabilized PSI suit exposed to fire test. making an accurate measurement of Thermal Integrity The skin simulant, developed by the shrinkage very difficult. At 900F most Naval Materials Laboratory, is com- of the PBI samples exhibited curling Another parameter partly related to posed of a resinous compound with and embrittlement; the Durette fabric thermal shrinkage is the ability of thermal and optical properties similar was embrittled and slightly shrunken. clothing to maintain structural in- to human skin. The severity of skin However, the Fypro fabric, despite its tegrity upon exposure to heat or fire. burns depends upon the integral of the 18 % shrinkage, remained relatively If a fabric ignites easily and burns time temperature profile. soft and flexible after the 900F ex- completely, leaving no structural resi- The ability of the skin to withstand posure. PBI fabric exhibits consider- due, the skin is left exposed and increased temperatures over selected ably less shrinkage upon exposure to burns can be severe. In contrast, a time periods can be summarized as hot air than does Nomex. However, material which even under high ther- follows: A skin temperature rise of even this thermal shrinkage may be mal exposure does not burst into flame 2lF is the approximate upper limit at too great for many potential applica- but only chars and pyrolizes while re- which a human subject would feel no tions. Fypro and Durette exhibit ap- taining its structural and dimensional pain nor sustain any burn injury even proximately one-half the shrinkage of integrity can render significant pro- if skin tissue were maintained at this PBI at temperatures up to 900F. Be- tection to the individual. Particularly temperature rise for an extended pe- cause of the shrinkage problem, ther- for thick materials, the outer layers riod of time. At a temperature rise of mal stabilization processes have been can burn. If the burned layers then do 32F, a human subject would sustain developed for PBI. Referring back to not break away and drop off, but first degree burns after 8 to 9.5 min- Fig. 3, this is a photo of a suit made rather maintain their shape and retain utes, and second and third degree from stabilized PBI (9), and identi- some strength and flexibility, they then burns thereafter. At a temperature rise fied in Table II as PBI-S. This work can become a fire-resistant layer, pro- of SOF, a human subject would sus- is still under development. tecting the fabric layers and the person within. This is the kind of ablative tain first degree burns after 2 to 3 50 seconds, and second and third degree mechanism that is employed to pro- burns thereafter. Thus you can see tect space vehicles from being burned that the human body cannot withstand PSI up by aerodynamic heating on re-en- large temperature increases for any 40 tering the earth's atmosphere. length of time, and this is why it is so I suggest that, for protective cloth- important that protective clothing ing, studies should be made of the function as good thermal insulators, ~ thermal insulation and mechanical ~30 as well as being nonflammable. L1J properties of fabrics during and after The heat flux caused by a flame im- (!) « their exposure to fire as these prop- ~ z erties may pertain to the protection of 0::20 the wearer. There has been little at- :I: (J) tention paid to this area of endeavor. Table VII-Temperature Rise in NML Skin Simulant for 3-Second Flame Exposure 10 Flame Impingement Max. Temperature Rise (OC) The ability of these candidate ma- After terials to withstand the impingement First Multiple 0 Exposure 3-Sec of a direct flame has also been studied. Fabric (3.Sec) Exposures 500 600 700 800 900 1000 The fabrics are directly exposed to a Natural Nomex 27 33 EXPOSURE TEMPERATURE (OF) propane gas burner under controlled Dope Dyed Nomex 35 39 PSI 24 34 Fig. 4-Shrinkage of dope dyed Nomex, conditions, and the temperature rise Durette 33 35 PSI, Fypro and Durette fabrics at ele- in a plastic skin simulant on the other Fypro 25 26 vated temperatures (average of warp side of the fabric is measured, via and filling). thermocouples, as a function of time.

38/6 ceo Vol. 4, No.1 h

1!' "......

Fig. 5-U.S. Army Natick Laboratories' fire pit test facility. Fig. 6-Clothed mannekin being tested at Natick fire pit. pinging on the skin simuiant was de- From observations made by Fabric The Nomex suit burned in the jet termined by exposing the simulant to Research Laboratories personnel, it fuei flame because its ignition tem- a 3-second standard flame exposure. was apparent that the PEI suits were perature, 1450-1500F, is lower than Without a protecting fabric, the tem- superior to those fabricated from the fuel flame temperature of 1800 to perature rise in the skin simulant was dope-dyed Nomex, while FR treated 2000F. The ignition temperature of about 61F, equivalent to a heat flux of cotton suits were poorest. Fig. 7 shows the PEI fabric at 1700F is also lower about 1.7 calories per square per meter the condition of the three suits, tested than the fuel flame temperature. How- per second. Most of the testing was in duplicate, after fire exposure. The ever, as has been previously stated, the carried out using this 3-second flame left suit in each set is PBI, the middle PBI must be exposed to high tempera- exposure, since this was the dwell time is Nomex, and the right is fire resis- tures for longer than 3 seconds before of clothed mannekins exposed to the tant cotton. Portions of both the FR there is any visible sign of ignition. In fire pit test. cotton and the Nomex coveralls were contrast, the Nomex ignites within sec- The average maximum temperature burning as the mannekins came out of onds. rises within the skin simulant, covered the flame. The temperature sensors un- Both the PBI and the Nomex suits with single layers of various fabrics for der the suit indicated that burns cover- exhibited considerable thermal shrink- 3-second flame exposures, are tabu- ing 50 to 60% of the body would have age-that of the PEI suit being some- lated in Table VII. Since the PEI occurred with the Nomex suits, what less than the Nomex. Shrinkage fabrics were virtually undamaged by while a maximum of 5 % of the body leads to intimate contact of the fabric 3-second flame exposures, some sam- surface was burned with the PEI suits. with the mannekin, and thereby a ples were deliberately exposed repeti- tively. Higher temperatures in the skin simulant were recorded during the second and third exposure, with a general leveling off of peak temperature after three, four or more exposures. Presumably this is due to the presence of moisture or other volatile materials in the specimen, which is evaporared during initial flame exposures. This demonstrates that the thermal protection potential of a fabric may depend significantly on its initial moisture content.

Fire Pit Tests

To correlate the laboratory tests with simulated performance tests, the Air Force and the Army conducted a series of tests at the U.S. Army Natick Laboratori.. fire test facility (Figs. 5 and 6). In the test, fully clothed mannekins are drawn over a 30-foot long pool of burning JP-4 aircraft fuel at a rate of 10 feet per second. Thus the total flame time is 3 seconds. Flame temperatures are in the order of mag- Fig. 7-Candidate suits after exposure to fire pit tests. Left to right PBI, Nomex, nitude of 1800 to 2000F. FR cotton, PBI, Nomex, FR cotton.

January 1972 ((D 7/39 Olney Medal Address a development which can contribute greatly in the field of protective cloth- Table VIII-Comparison of Rankings NonflammableProducts ing. At the moment it is being manu- of Hot Weather Uniforms factured experimentally only under (From U.S. Army Natick Labs government sponsorship. As taxpay- TR71-40-CE) ers you may be interested to learn that Temperature- Garment Area Damage until recently the cost was $200 per Rank pound, but is now only $175 per Index Rank Uniform System pound. It is my understanding that if 1 PBI 1 3 Aromatic Polyamide A 2 the Department of Defense sees fit to 2 Army Tankers (CA)* 3 proceed with a full-scale plant, the 8 PBI{CA* 4 price conceivably could come down to 4 Aromatic POlyamide B 5 larger temperature build-up on the about $5 per pound in quantities of a 6 Aromatic Polyamide C 6 mannekin surface. A suit fabricated million pounds. 7 Army 2-Piece (CA)* 7 from thermally stabilized PBI-S fabric Some other attributes of PBI are its 5 Modified Aromatic 8 (Fig. 3) exhibited no noticeable di- excellent soft hand, with good POlyamide mensional changes and no damage af- strength, toughness and abrasion re- * CA = Commercial Aromatic Polyamide ter three passes through the fire pit. sistance. It has a moisture regain of Table VIII is from a recent report about 12 %, and this may be a factor by the Natick Laboratories entitled in making it a comfortable fabric to "The Behavior of Protective Uniforms wear. Its prime deficiency is that, like in modified forms so that they will in Large Scale Simulated Fires" (10). Henry Ford's Model T, you can have have far better flame resistances. A temperature-area index, based upon it in almost any color you want pro- The point is that for protective the area of the mannekin that has sus- vided it's golden. Dyeing and light clothing we now do have materials that tained unacceptable temperature in- fastness problems remain to be solved. will give significantly greater protec- creases, is employed to assess the pro- Finally, I must state that I am not tion to people in hazardous occupa- tective capabilities of the various suits. here to tell you that the PBls or tions, and we should be thinking about A garment damage rank is also listed. Nomexes or other high temperature how these fibers can be used for con- Of the materials tested, including both exotic fibers will solve all of the flam- sumer applications. commercial and experimental polya- mable fabric problems, and that in fu- The point is that we don't need a mides, the PBI appears to have taken ture years our most popular and wide- PBI or a Durette to withstand the first place. ly used fibers-cotton, wool, rayon, everyday hazards that children and old By now you must realize that I nylon, polyester and the acrylics-will people particularly encounter-the am personally extremely enthusiastic no longer be produced. I hope that child playing with matches, or the about the potential of PBI. I think it is they will continue to be produced but woman brushing her housecoat against a gas stove while she is scrambling the eggs. The point is that so many clothing fires do stem from relatively short contacts with a flame. If we can develop materials or treat- ments that can raise ignition temperatures and times and LOis, we will have gone a long way towards protecting people from unnecessary fire hazards. Effort leading to the reduction of such hazards must be continued. ceo

References Hussong20-armSolid. (I) Innes, R. L., R. Schmitt, A. S. Goldman, Color Skein Dyeing A. McKinley and M. Dobrkovsky, Etiological Machine.Othermodels Study of Burn Injuries. Proceedings of the Third availablewith 1 to 80 AnnuaL Meeting, Information Council on Fabric Flammability. 1969. p3. arms. (2) Crikelair, George F., Medical Aspects of Clothing Burns, Bulletin 45, Gottlieb Dutt- weiler Institute for Economic and Social Studies, .Dyes 3 to 4 times Ruschlikon-Zurich, 1969. faster than any other (3) Bush, V., The Key to Accomplishment, U.S. Institute for Textile Research, MIT Press, existing machine Cambridge, Mass., 1932. .Cuts labor costs by 3~ to 8~ per HUSSONG's new development - the (4) BernskiOld, A., Ignition and Burning Properties of Textiles, Doktorsavhandlingar Vid pound (proven by ext~nsive tests) first major skein dyeing breakthrough in Chalmers Tekniska Hogskola, Goteborg, Swe- .Saves water, dyestuffs and chemi- decades - can save you big money! den, 1970. cals (5) Freeston, W. D. Jr., Flammability and This machine dyes skeins in a single Heat Transfer Characteristics of Cotton, Nomex .Dyes uniformly every time color up to 108" long in !f3 to 1,4 the and PBI Fabrics, Journal of Fire and Flam- Handles skeins up to 108" in size time of any other equipment. You can mability, Vol. 2, January 1971, p57. . (6) Fenimore, C. P. and F. J. Martin, Candle and easily adjusts for different process up to 8 batches of skeins every Type Test for Flammability of Polymers, Mod- lengths of skeins 8 hours, depending on material, color ern Plastics, Vol. 43, 1966, p141. (7) Tesoro, G. C. and C. H. Meiser Jr., .Available with 1 to 80 arms with a and shade. Typical production rates are Some Effects of Chemical Composition on the capacity of 20 lb. of popular 72" 2400 to 3200 Ibs. for a 20-arm machine Flammability Behavior of Textiles. Textile Re- search Journal, Vol. 40, 1970, p430. skeins per arm (more for larger in an 8-hour shift. Think of the money (8) Miller, B. and C. H. Meiser, Jr., Steady skeins) you can save on labor alone. State Burning of Textiles in Flowing °2/N2 Mixtures, Textile Chemist and Colorist, Vol. 2, 1970, p205. (9) Schulman. S. and R. M. Stanton, Non- Formore . / ~ HUSSONG.WALKER.DAVISCO. flammable PBI Fabrics for Prototype Air Force information, Flight Suits. U.S. Air Force Technical Report "~~)l'lt- Valetta & Coral 5t5., Philadelphia,Pa. 19124 AFML-TR-70-178, November 1970. write or phone "t:~'~':' Phone (215) 743-4240 Telex 83-1318 (10) U.S. Army Natrick Laboratories, Re- . search and Engineering Division, The Behavior today. ~. '.~' .. Representedby of Protective Uniforms in Large Scale Simu- ",.,v' PO Box6~76.GreenVl:le.SC 29606. 570317 lated Fires, TR 71-40-CE, March 1971.

40/8 ceo Vol. 4, NO.1