Flame retardants grafting

Reactive Flame Retardants. Reactive flame retardants become a part of the polymer by either becoming a part of the backbone or by grafting onto the backbone. Choice of reactive flame retardant is more complex than choice of an additive type. The reactive flame retardant can exert an enormous effect on the final properties of the polymer. There are also reactive halogenated compounds used as iatermediates to other flame retardants. Tables 8 and 9 Hst the commercially avaHable reactive flame retardants and iatermediates. 

Brominated Styrene. Dibromostyrene [31780-26 ] is used commercially as a flame retardant in ABS (57). Tribromostyrene [61368-34-1] (TBS) has been proposed as a reactive flame retardant for incorporation either during polymerization or during compounding. In the latter case, the TBS could graft onto the host polymer or homopolymerize to form poly(tribromostyrene) in situ (58). 

Alkenylsuccinic anhydrides made from several linear alpha olefins are used in paper sizing, detergents, and other uses. Sulfosuccinic acid esters serve as surface active agents. Alkyd resins (qv) are used as surface coatings. Chlorendric anhydride [115-27-5] is used as a flame resistant component (see Flame retardants). Tetrahydrophthalic acid [88-98-2] and hexahydrophthalic anhydride [85-42-7] have specialty resin appHcations. Gas barrier films made by grafting maleic anhydride to polypropylene [25085-53-4] film are used in food packaging (qv). Poly(maleic anhydride) [24937-72-2] is used as a scale preventer and corrosion inhibitor (see Corrosion and corrosion control). Maleic anhydride forms copolymers with ethylene glycol methyl vinyl ethers which are partially esterified for biomedical and pharmaceutical uses (189) (see Pharmaceuticals). 

Acrylonitrile—Butadiene—Styrene. ABS is an important commercial polymer, with numerous apphcations. In the late 1950s, ABS was produced by emulsion grafting of styrene-acrylonitrile copolymers onto polybutadiene latex particles. This method continues to be the basis for a considerable volume of ABS manufacture. More recently, ABS has also been produced by continuous mass and mass-suspension processes (237). The various products may be mechanically blended for optimizing properties and cost. Brittle SAN, toughened by SAN-grafted ethylene—propylene and acrylate mbbets, is used in outdoor apphcations. Flame retardancy of ABS is improved by chlorinated PE and other flame-retarding additives (237). 

This is another important and widely used polymer. Nanocomposites have been prepared based on this rubber mostly for flame-retardancy behavior. Blends with acrylic functional polymer and maleic anhydride-grafted ethylene vinyl acetate (EVA) have also been used both with nanoclays and carbon nanotubes to prepare nanocomposites [65-69]. 

Polymer mixtures of aromatic PC, ABS graft polymer and styrene-containing copolymers and monophosphates are described as flameproofing additives (20). It has been claimed that phosphonate amines are superior flame retardants for PC/ABS molding compositions (21). 

Figure 9a. Electron spectra from flame retardant coatings plasma grafted to fabric.

TG-FTIR Vulcanisation [32], ageing characterisation [39, 48], sulphur components in rubber [31], polyurethanes [37], polymer degradation mechanisms [30, 40, 41], identification of base polymers [36, 43, 44], thermal stability [46], grafted flame retardants [47], differentiation of EVA rubbers [45] and AN-NBR rubbers [36, 44], degradation of chlorinated natural rubber [42],... 

In line with the above discussion, the properties of grafts must also depend on the location of the graft copolymer. Properties such as abrasion, enhanced adhesion, wetting and so on only need surface modification. Flame retardancy, water sorbency, and certain other properties, on the other hand, need essentially bulk grafting. These differences can be achieved rather easily in practice and the differences have been clearly demonstrated in a number of cases. 

In this paper, the surface grafting of rayon fabrics with nitrogen and phosphorus containing polymers in cold plasma is studied. The analytical data (IR spectroscopy, TGA, electron microscopy, elemental analysis, etc.) indicate the formation of grafted copolymers. The grafted rayon fabrics present improved flame-retardant properties, the best behavior was proved by those grafted with polyurea of phosphinic acid. 

PP is commercially modified by radical grafting with maleic anhydride to give maleated PPs used as compatibilizers for additives such as nanoclays. Similar strategies can be used to graft P-containing monomers to PPs. These copolymers, when blended with virgin PP, also allow com-patibilization with nanoclays but in addition work synergistically with the clays to improve flame retardance.51... 

Abdel-Mohdy, F. A., Graft copolymerization of nitrogen- and phosphorus-containing monomers onto cellulosics for flame-retardant finishing of cotton textiles, J. Appl. Polym. Sci., 2003, 89, 2573-2578. 

Kaur, I., Sharma, V., and Sharma, R., Development of flame retardant cotton fabric through grafting and post-grafting reactions, Indian J. Fibre Textile Res., 2007, 32, 312-318. 

Tsafack, M. J. and Levalois-Grutzmacher, J. L., Plasma-induced graft-polymerization of flame retardant monomers onto PAN fabrics, Surf. Coat. Technol., 2006, 200, 3503-3510. 

---