Flame-retardant behaviour polymer

Modesti, M. Lorenzetti, A. Improvement on fire behaviour of water blown PIR-PUR foams Use of an halogen-free flame retardant. Eur. Polym. J. 2003, 2, 263-268. 

Polyethylene (PE) is one of the most used thermoplastic polymers. PE is versatile, easy to process and has a low cost. It is used in diverse apphcations ranging from construction, vehicles to domestic products, packaging, toys, etc. Some of the limitations of PE are the poor mechanical behaviour under high stress, flame retardant behaviour, low resistance to UV radiation, the permeability to certain gases, and the fact that it is not biodegradable. 

The use of copolymers is essentially a new concept free from low-MW additives. However, a random copolymer, which includes additive functions in the chain, usually results in a relatively costly solution yet industrial examples have been reported (Borealis, Union Carbide). Locking a flame-retardant function into the polymer backbone prevents migration. Organophosphorous functionalities have been incorporated in polyamide backbones to modify thermal behaviour [56]. The materials have potential for use as fire-retardant materials and as high-MW fire-retardant additives for commercially available polymers. The current drive for incorporation of FR functionality within a given polymer, either by blending or copolymerisation, reduces the risk of evolution of toxic species within the smoke of burning materials [57]. Also, a UVA moiety has been introduced in the polymer backbone as one of the co-monomers (e.g. 2,4-dihydroxybenzophenone-formaldehyde resin, DHBF). 

Substances applied to or incorporated in a combustible material (e.g. organic polymers, nylon, vinyl and rubber, etc.) to reduce flammability. Act by retarding ignition, control/douse burning, reduce smoke evolution. Slow down or interrupt the self-sustained combustion cycle when the heat-flux is limited. Flame retardants (FRs) improve the combustion behaviour and alter the combustion process (cool, shield, dilute, react) so that decomposition products will differ from nonflame retarded articles. FRs are usually divided into three classes ... 

B. Perret and B. Schartel, The effect of different impact modifiers in halogen-free flame retarded polycarbonate blends - ii. fire behaviour, Polym. Degrad. Stab., In Press, Corrected Proof, 2009. 

Price, D., Cunliffe, L. K., Bullett, K. J., Hull, T. R., Milnes, G. J., Ebdon, J. R., Hunt, B. J., and Joseph, R, Thermal behaviour of covalently bonded phosphate and phosphonate flame retardant polystyrene systems, Polym. Degrad. Stab., 2007, 92, 1101-1114. 

Gao, F., Tong, L., and Fang, Z. 2006. Effect of a novel phosphorous-nitrogen containing intumescent flame retardant on the fire retardancy and the thermal behaviour of poly(butylene terephthalate). Polym. Deg. Stab. 91 1295-1299. 

Schartel B, Balabanovich AI, Braun U, Knoll U, Artner J, Ciesielski M, Doring M, Perez P, Sandler JKW, Altstadt V, Hoffmann T, Pospiech D. Pyrolysis of epoxy resins and fire behaviour of epoxy resin composites flame-retarded with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide additives. J. Appl. Polym. Sci. 2007 104 2260-2269. 

Padbury, S.A., Horrocks, A.R., and Kandola, B.K. 2003. The effect of phosphorus-containing flame retardants and nanoclay on the burning behaviour of polyamides 6 and 6.6. Proceedings of the 14th Conference Advances in Flame Retardant Polymers, Stamford, Norwalk, CT Business Communications 2003. 

Modesti, M. Lorenzetti, A. Simioni, F. Checchin, M. Influence of different flame retardant on fire behaviour of modified PIR/PUR polymers. Polym. Degr. Stab. 2001, 74, 475-479. 

Schartel, B. Braun, U. Balabanovich, A.I. et al. Influence of the oxidation state of phosphorus on the decomposition and fire behaviour of flame-retarded epoxy resin composites. Polymer 2006, 47, 8495-508. 

Modesti, M. Lorenzetti, A. Besco, S. Hrelja, D. Semenzato, S. Bertani, R. Michelin, R.A.. Synergism between flame retardant and modified layered silicate on thermal stability and fire behaviour of polyurethane nanocomposite foams. Polym. Degrad. Stab. 2008, 93, 2166-2171. 

Wang, Z., Shen, X., Fan, W., Hu, Y., Qu, B., andZou, G., Effects of poly(ethylene-co-propylene) elastomer on mechanical properties and combustion behaviour of flame retarded polyethylene/magnesium hydroxide composites, Polym. Int., 2002, 51(7), 653-657. 

This chapter discusses the dynamic mechanical properties of polystyrene, styrene copolymers, rubber-modified polystyrene and rubber-modified styrene copolymers. In polystyrene, the experimental relaxation spectrum and its probable molecular origins are reviewed further the effects on the relaxations caused by polymer structure (e.g. tacticity, molecular weight, substituents and crosslinking) and additives (e.g. plasticizers, antioxidants, UV stabilizers, flame retardants and colorants) are assessed. The main relaxation behaviour of styrene copolymers is presented and some of the effects of random copolymerization on secondary mechanical relaxation processes are illustrated on styrene-co-acrylonitrile and styrene-co-methacrylic acid. Finally, in rubber-modified polystyrene and styrene copolymers, it is shown how dynamic mechanical spectroscopy can help in the characterization of rubber phase morphology through the analysis of its main relaxation loss peak. 

This volume is including information about thermal and thermooxidative degradation of polyolefine nanocomposites, modeling of catalytic complexes in the oxidation reactions, modeling the kinetics of moisture adsorption by natural and synthetic polymers, new trends, achievements and developments on the effects of beam radiation, structural behaviour of composite materials, comparative evaluation of antioxidants properties, synthesis, properties and application of polymeric composites and nanocomposites, photodegradation and light stabilization of polymers, wear resistant composite polymeric materials, some macrokinetic phenomena, transport phenomena in polymer matrix, liquid crystals, flammability of polymeric materials and new flame retardants. 

Intrinsically non-flammable polymers are few, but phenolic resins have a good reputation both in Are and smoke performance, which has resulted in their becoming increasingly favoured for reinforced plastics structures, for example, underground transport, where such concerns are greatest. Polyether ether ketone (PEEK) is also a low fire and smoke polymer. Unsaturated polyesters, vinyl esters and epoxy resins bum readily, but modified versions are available with improved behaviour. For example, both bromine and chlorine are used extensively in the form of chlorendic (HET) acid, tetrachlorophthalic anhydride (TCPA) and tetrabromo-phthalic anhydride (TBPA) which can be reacted into the polyester in small quantities and can act as permanent (non-migrating) flame retardants. 

Zhang and co-workers [79] investigated flame retardency and thermal behaviour of rigid PU foams prepared with different blowing agents and FR. Char yields produced upon combustion of the polymers were evaluated by the Butler Chimney Standard test method and pyrolysis - mass spectrometry (pyrolysis at 700 °C). 

There are several references to this technique pioneered by Price [81-91] and his co-workers. Two systems have been investigated to model different aspects of flame-retarded polymer behaviour in a fire. One system uses a continuous laser to model radiative heat at a level similar to that from a burning item in a room Are and the other uses a pulsed laser to model conditions immediately behind the flame front. 

The thermal properties of polyesters are of the greatest importance for their end applications. The important features of a polymer, such as bond strength, inter-and intra-molecular forces, resonance stability, crystallinity, structural imperfections and molecular weight, are responsible for their thermal behaviour. Long oil polyester resin and styrenated polyester resin are made flame retardant by the incorporation of bis-pyridine, bis-tribromophenoxo copper complex and polydibromophenylene oxide. 

Depending on the distribution of micro/nanofiller in the polymer matrix, the composites may be classified as microcomposites or nanocomposites. These two types of composites differ significantly with respect to their properties. The nanocomposites show improved properties compared to pure polymer or that of microcomposites. It started only back in 1990, when Toyota research group showed that the use of montmorillonite can improve the mechanical, thermal, and flame retardant properties of polymeric materials without hampering the optical translucency behaviour of the matrix. Since then, the majority of research has been focused in improving the physicochemical properties, e.g. mechanical, thermal, electrical, barrier etc. properties of polymer nanocomposites using cost effective and environmental friendly nanofillers with the aim of extending the applications of these materials in automotive, aerospace, construction, electronic, etc. as well as their day to day life use. The improvements in the majority of their properties have invariably been attributed... 

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