Polyphenylene oxide styrene-modified

The growth of these materials is reflected in the number of polymers which are being glass reinforced. These include polypropylene, polystyrene, styrene acrylonitrile, nylon, polyethylene, acrylonitrile-butadiene-styrene, modified polyphenylene oxide, polycarbonate, acetal, polysulfone, polyurethane, poly (vinyl chloride), and polyester. In addition, the reinforced thermoplastics available now include long-fiber compounds, short-fiber compounds, super concentrates for economy, a combination of long and short fibers, and blends of polymer and fibrous glass. 

In both Europe and the United States, aluminum trihydrate, or ATH [Al(OH)3)], has by far the largest share of the mineral flame-retardant market however, magnesium hydroxide presently has the highest growth rate. To date, most of the research using magnesium hydroxide has focused on thermoplastics, including ethylene-vinyl acetate copolymer (EVA), polypropylene, acrylonitrile-butadiene-styrene (ABS) copolymer, and modified polyphenylene oxide (Hornsby and Watson, 1986). 

Plastics that are readily bonded with induction methods include all grades of acrylonitrile butadiene styrene (ABS), nylon, polyester, polyethylene, polypropylene, and polystyrene, as well as those materials often considered more difficult to bond such as acetals, modified polyphenylene oxide, and polycarbonate. Reinforced thermoplastics with filler levels up to 65 pCTcent have been joined successfully. Many combinations of dissimilar materials can be bonded with induction welding processes. 

The above materials are crystalline polymers, and such materials have generally superior frictional, wear and fatigue properties, compared with amorphous polymers. However, amorphous polymers show lower mould shrinkage and where dimensional accuracy is paramount they may be preferred. Suitable engineering types are polycarbonate (PC) and noryl (styrene modified polyphenylene oxide). 

Figure 1 Polymer interpretation chart. PAI, polyamideimide PC, polycarbonate UP, unsaturated polyester PDAP, diarylate phtalate resin VC-VAc, vinyl chloride-vinyl acetate copolymer PVAc, polyvinyl acetate PVFM, polyvinyl formal PUR, polyurethane PA, polyamide PMA, methacrylate ester polymer EVA, ethylene-vinyl acetate copolymer PF, phenol resin EP, epoxide resin PS, polystyrene ABS, acrylonitrile-butadiene-styrene copolymer PPO, polyphenylene oxide P-SULFONE, poly-sulfone PA, polyamide UF, urea resin CN, nitrocellulose PVA, polyvinyl acetate MC, methyl cellulose MF, melamine resin PAN, polyacrylonitrile PVC, polyvinyl chloride PVF, polyvinyl fluoride CR, polychloroprene CHR, polyepichlorohydrin SI, polymethylsiloxane POM, polyoxy-methylene PTFE, polytetrafluoroethylene MOD-PP, modified PP EPT, ethylene-propylene terpolymer EPR, ethylene-propylene rubber PI, polyisoprene BR, butyl rubber PMP, poly(4-methyl pentene-1) PE, poly(ethylene) PB, poly(butene-l). (Adapted from Ref. 22, p. 50.)...

The modifier forms a particulate dispersion in the polymer phase, and under stress, crazing develops around modifier particles. Moreover, the addition of a compatibilizer improves particle dispersion and interfacial adhesion, resulting in engaged toughness. Rubber modified polystyreue, high-impact polystyrene (HIPS), or polyphenylene oxide can be used as a modifier. The compatibilizer can be a triblock copolymer of styrene-ethylene-propylene. The copolymer can even be random. 

Nelson [136] has reported studies of zinc, zinc oxide, and zinc borate in coatings on or as a filler in modified polyphenylene oxide (m-PPO). Zinc arc spray, or zinc, zinc borate, and zinc/zinc borate in epoxy coatings showed a substantial reduction of flame spread index (ASTM E-162) (I,) for m-PPO. Zinc oxide in epoxy, however, showed a dramatic increase in I, on m-PPO. Zinc arc spray on m-PPO led to enhanced stability in the 500-600°C range in both isothermal and GC/MS experiments. It was speculated that since zinc melts at 420OC, just at the early stage of decomposition of m-PPO, this could allow intimate contact with the charring substrate. As in pure polystyrene, char formation is enhanced in air in m-PPO, and this was thought to be enhanced further by the presence of zinc. Indeed it was observed that volatilization of small molecules is reduced for m-PPO with zinc present at temperatures under 700°C, with preference for volatilization of the triaryl phosphate flame retardant, styrene trimer, and PPO dimers. 

Property data for GRTP s are presented in two major breakouts. In the first breakout, the basic resins—styrene acrylonitrile (SAN), polycarbonate, polysulfone, polyacetal, polypropylene, polyphenylene oxide (PPG), nylon, modified PPG, and polyvinyl chloride—are treated as the independent variables and the physical, mechanical, electrical, thermal, chemical, and weathering characteristics are treated as the dependent variables. In the second breakout, the functional relationships are reversed, te., the properties are the independent variable and the resins are the dependent variable. ASTM test methods by which the physical values were determined are listed. The. physical data versus resins are presented in both tabular and graphic form. 

Styrene-modified polyphenylene oxide is used in both filled and unfilled grades. It can be produced in low flammability versions by the incorporation of flame retardant additives. It has good mouldability in all but the most complex tools and is fairly widely employed. In some cases it has taken over from polycarbonate. 

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