Nylon burning tests

Flammability. Most nylons ate classified V-2 by the Underwriters Laboratory UL-94 test, which means that these nylons are self-extinguishing within a certain time-scale under the conditions of the test. They achieve this performance by means of giving off burning drips. 

Artificial surfaces must be resistant to cigarette bums, vandaUsm, and other harm. Fire resistance is most critically evaluated by the NBS flooring radiant panel test (10). In this test, a gas-fired panel maintains a heat flux, impinging on the sample to be tested, between 1.1 W/cm at one end and 0.1 W/cm at the other. The result of the bum is reported as the flux needed to sustain flame propagation in the sample. Higher values denote greater resistance to burning results depend on material and surface constmction. Polypropylene turf materials are characterized by critical radiant flux indexes which are considerably lower than those for nylon and acryflc polymers (qv) (11). 

Various polymeric materials were tested statically with both gaseous and liquefied mixtures of fluorine and oxygen containing from 50 to 100% of the former. The materials which burned or reacted violently were phenol-formaldehyde resins (Bakelite) polyacrylonitrile-butadiene (Buna N) polyamides (Nylon) polychloroprene (Neoprene) polyethylene polytriflu-oropropylmethylsiloxane (LS63) polyvinyl chloride-vinyl acetate (Tygan) polyvinylidene fluoride-hexafluoropropylene (Viton) polyurethane foam. Under dynamic conditions of flow and pressure, the more resistant materials which binned were chlorinated polyethylenes, polymethyl methacrylate (Perspex) polytetraflu-oroethylene (Teflon). 

Cold cure" or high resilience PU foams tended to liquify before igniting were developed and gave good results in standard tests such as BS 4735(25) (similar to the discontinued ASTM D1692) but could still burn when used with flammable fabrics in furniture (Table IV). However they have been used most successfully in the UK in combination with flame retarded cotton interliners and fabrics of low flammability e.g. wool, nylon, FR cotton etc. and formed the basis of public area furniture used in the UK since the early 1970 s (Table V). 

CFR 1610 states 1610.62 (4) Note 2—Some textiles never exhibit unusual burning characteristics and need not be tested. 16 CFR 1610.37 (d). Such textiles include plain surface fabrics, regardless of the fiber content, weighing 2.6 oz. or more per sq. yd., and plain and raised surface fabrics made of acrylic, modacrylic, nylon, olefin, polyester, wool, or any combination of these fibers, regardless of weight. 

Flame test with nylon 6. Burns with frothing and a blue-yellow flame. 

Self-extinguishing adj. A somewhat loosely used term denoting the ability of a material to cease burning after the source of flame has been removed. PRV, vinyl chloride-acetate co-polymers, polyvinylidene chloride, some nylons, and casein plastics are examples of self-extinguishing materials. Troitzsch J (2004) Plastics flammability handbook principle, regulations, testing and approval. Hanser-Gardner Publications, New York. Tests for comparative flammability of hquids, UI 340. Laboratories Incorporated Underwriters, New York, 1997. 

There are many types of nylons with a specific gravity ranging from 1.04 to 1.17. All types burn with blue flames and yellow tips and give off a burnt wool or hair odor. Nylon self-extinguishes on removal of the flame. Phenol, m-cresol, and formic acid are the most common solvents. Different types of nylons can be identified by the Fisher-Johns melting-point test (ASTM D 789). Solubility and specific gravity tests are also used to differentiate between the types of nylons. However, infrared spectroscopy is the best method for positive identification. 

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