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FIBERS AND THEIR BLENDS IntroduclionA knowledge of the behavior of textiles at elevated temperatures has become increasingly important in many industrial and military The products of the thermal decomposition of fibers and the mechanisms of their thermal degradation are factors that must be considered in the solution of the problem of providing effective flame and thermal protection in clothing .6-8 In order to determine the behavior of textile fiber-forming polymers of different chemical compositions at high temperatures (400 to 1000" F.) 18 different natural, regenerated, derivative, or synthetic fiber types (TABLE 1) were studied. The materials represented a cross section of commercially available fibers and were used in bulk form. A series of 50/50 blends of these fibers with cotton was prepared in order: (1) to study the behavior of fiber blends at high temperatures; (2) to compare the behavior of the blends with that of the individual components; and (3) to elucidate the mechanisms of interactions at elevated temperatures of chemically different fibers in a blend.The thermal responses of nylon and cotton blended in the proportion 10/90, 25/75, 50150, 75/25, and 90/10 were also determined so as to investigate the effect of concentration of the admixed component (nylon) on the behavior of the blend (nylon/cotton) at high temperatures. ExperimentalAll fiber types except Vinyon-HH were Soxhlet extracted with carbon tetrachloride, rinsed in hot water, and air dried for 48 hours prior to use. The blends were prepared on a laboratory-size mechanical b1ender.O Two-hundredand-fifty-milligram samples, shaped in small balls, were pyrolyzed on a 3 X 3-inch piece of 5-mil aluminum sheeting in an aluminum-lined muffle furnace. The floor of the furnace was covered with a corrugated aluminum platform. These precautions were taken in order to minimize temperature variations within the furnace. The previously weighed specimens were placed in the furnace for 2 min., removed, and reweighed after a 24-hour conditioning period. The temperature range of the studies was 400 to 1OOO" F.; data were taken at intervals of approximately 50" F. Data and ResultsMelting characteristics. The fibers could be classified into two groups by an examination of the residues after pyrolysis: