Halogen-containing polymer systems

Coated fillers have been evaluated in a range of halogen-containing polymer systems, including rigid and flexible polychloroprene (Neoprene), and in thermoplastic and thermosetting materials... 

In general, tin compounds do not exhibit flame-retardant properties in halogen-free polymer systems, unless the composition contains a high inorganic filler loading. However, tin additives often act as smoke suppressants in non-halogenated polymers. 

Blends based on halogen-containing polymers are also significant [30-32]. Those based on halo-genated polyolefin/ethylene interpolymer blends are claimed to be single-phase systems [32]. They are often used where solvent and fire resistance is important. PVC/nitrile rubber/dioctyl phthalate blends are used in similar applications and also in footwear [30-32]. 

Louisville, Ky., 8th-11th Oct.1996, Paper 6, pp.24. 012 HEAT RESISTANT CURING SYSTEM FOR HALOGEN-CONTAINING POLYMERS... 

The first fire retardant polyester containing a reactive fire retardant monomer was introduced by the Hooker Electrochemical Corporation in the early 1950 s containing chlorendic acid as the reactive monomer (6). This pioneering development rapidly led to the introduction of variety of reactive halogen and phosphorus containing monomers, such as tetrabromophthalic anhydride, chlorostyrene and tetrabromobisphenol A, which found application in a wide variety of condensation polymer systems. 

Moreover, the development of new strategies for surface modifications of nanoparticles with compounds having FR activity could provide a new field of research on FR systems. The use of novel phosphorus-, nitrogen-, or halogen-containing modifiers, instead of alkylammonium ions, for layered silicates seems promising. FR action conferred by the surface modifier can be combined with action due to composite morphology, particularly when the host polymer is a polymer blend instead of a pure polymer. 

With halogen-containing systems, zinc borate can partially or completely replace the antimony synergist in PVC, notably wire and cable, wallcoverings, roof membranes and tarpaulins. It is also effective in polyolefins, elastomers, polyamides and epoxy polymers while, in halogen-free systems, it can be used in conjunction with alumina trihydrate, magnesium hydroxide or red phosphorus. 

Additives functioning in the vapor phase exhibit the highest efficiency because they interfere with the combustion chemistry. Total load levels as low as 3 wt% are sufficient for certain flammability performance requirements. The halogen-containing systems that function in the vapor phase are characterized by higher heat releases than systems operating in the condensed phase. The steps involved in the combustion of polymers as described by Troitzsch (10), shown in Fig. 4.20, are summarized below. 

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