Flammability behavior

Aerosols and Mists The flammability behavior of vapors is affected by the presence of liquid droplets in the form of aerosols or mists. Aerosols are liquid droplets or solid particles of size small... 

It is known that increased char yield is usually associated with improved flammability behavior ( 1). This can be understood if one considers that the volatile flammable products can only diffuse with difficulty through the char, and that the thermal conductivity of a porous char layer is relatively poor (2). The structure of the polymer can contribute to the amount of char formed based on the character of the functional groups present and the nature of the backbone (2,3). Ritchie ( ) found that for a series of unsaturated polyesters and their copolymers, the temperatures at which carbon dioxide is eliminated was in the range of 280 to 345°C depending on the structure of the polyester. Aliphatic polyesters and their copolymers have less thermal... 

Whereas UL 94 delivers only a classification based on a pass-and-fail system, LOI can be used to rank and compare the flammability behavior of different materials. In Figure 15.2 the increasing LOI values are presented for different polymers as an example POM = poly(oxymethylene), PEO = poly(ethyl oxide), PMMA = poly(methyl methacrylate), PE = polyethylene), PP, ABS, PS, PET = polyethylene terephthalate), PVA = poly(vinyl alcohol), PBT, PA = poly(amide), PC, PPO = poly(phenylene oxide), PSU, PEEK = poly(ether ether ketone), PAEK = poly(aryl ether ketone), PES, PBI = poly(benzimidazole), PEI = poly(ether imide), PVC = poly(vinyl chloride), PBO = poly(aryl ether benzoxazole), PTFE. The higher the LOI, the better is the intrinsic flame retardancy. Apart from rigid PVC, nearly all commodity and technical polymers are flammable. Only a few high-performance polymers are self-extinguishing. Table 15.1 shows an example of how the LOI is used in the development of flame-retarded materials. The flame retardant red phosphorus (Pred) increases... 

Kandola, B.K., Horrocks, A.R., Padmore, K., Dalton, J., and Owen, T. 2006. Comparison of cone and OSU calorimetric techniques to assess the flammability behavior of fabrics used for aircraft interiors, Fire Mater., 30(4) 241-255. 

Degradation and Flammability Behavior of Biofiber Composites and Biofiber/Glass Fiber Reinforced Polypropylene Hybrid Composites... 

Gases Flammable behavior under normal temperature and pressure in contact with air... 

The selection of solvents is additionally restricted by legal requirements for storage and transport based on the combustion and flammability behavior of the paint. 

The flammability behavior of some polymer blends is summarized in Table 6.7. Here one can also obtain some useful information thus, if the material burns readily while melting slowly and emits a deflnite paraffinic odor, these point to a polyolefin blend. Highly sooty flames are a deflnite indication that aromatic structures are present, while the odor of burnt horn indicates nitrogen-containing components. The identification of PVC in blends is relatively easy because generally a stinging smell of hydrochloric acid develops while the material usually burns very poorly. When polycarbonates are present in the blend, a typical odor of phenol is noticed in most cases. 

Acrylics are also similar to cotton in smoke generation. National Bureau of Standards smoke cabinet results are shown in Figure 12.48 for acrylic, modacrylic, nylon, PVC, cotton, and wool [376]. These data show wool to give the highest smoke density while nylon and PVC give the lowest, under these burning conditions. The modacrylics are actually somewhat worse in smoke generation than acrylics. The thermal and flammability behavior of textile materials has been reviewed in detail by Rebenfeld et al. [377], Lewin et al. [378], and Lewin [379]. 

Tesoro GC, Meiser CH. Some effects of chemical composition on the flammability behavior of textiles. Textil Res J 1970 40(5) 430-6. 

Tesoro GC, Rivlin J. Flammability behavior of experimental blends. Textil Chem Color 1971 3(7) 156-60. 

All the properties in this section, individually or in combination with other properties, provide the understanding of the flammability behaviors of polymers and assessment of various hazards in fires. 

Hapuarachchi TD, Peijs T, Bilotti E (2013) Thermal degradation and flammability behavior of polypropylene/clay/carbon nanotube composite systems. Polym Adv Technol 24 331-338... 

Flammability Depends on the solvent substance itself is not flammable Behavior in Are Produees toxic gases and vapor Decomposition temperature (°C) >191... 

Polystyrene is very difficult to cross-link by electron beam radiation or by peroxide without destroying its properties. As a result, applications have not been developed. The methyl groups of poly-PMS, by contrast, provide susceptible positions for such a reaction. PMS polymers can be cross-linked effectively by electron-beam radiation. This unique property of tpoly-PMS could open several new markets. Crosslinking turns a PMS-based thermoplastic into a thermoset resin, significantly improving its grease resistance and flammability behavior. 

There are various stages in the pyrolytic degradation and combustion of volatile products leading to the flammability behavior of pol3nners. Mechanisms to decrease flammability involve modifying condensed phase or volatile phase reactions. The reported studies relate our recent progress in the understanding and controll of these mechanisms. 

Some general known relationship between flammability and polymer structure are reviewed. Our studies on relating polymer end groups and molecular weights to flammability indicated that the known thermal degradation mechanisms for nylon 6 and polyethylene terephthalate (PET) are, in part, related to their flammability behavior. 

The question of the flammability behavior of similar flame retarding structures when used as additives or as comonomers in PET is discussed. For the case of structures related to tetrabromo-bisphenol-A, there was little difference, but for those containing triphenylphosphine oxide related structures a switch from volatile phase to condensed phase mechanisms was possible. 

According to the exposure conditions, severe, moderate, or light, various classes of flame retarded products are designed. The following codes govern flammability behavior in building A, B, C or I, II, III, etc., for low to easy flammability according to ASTM El 19 and E84 DIN 4102. 

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