Polypropylene copolymers-Appearance Degradation

The dithiocarbamates have the pentacoordinate binuclear structure (44). The diamyl- and diethyl-dithiocarbamate complexes have been found to inhibit the hardening of asphalt, but the effect appears too weak to be useful.127 The latter complex is an effective antioxidant for polyethylene,128 polypropylene,129 polystyrene,130 poly(methyl methacrylate)130 and an isoprene-styrene copolymer.131 The di-n-butyldithiocarbamate complex is important in the vulcanization and injection moulding of rubber,132 as a stabilizer against photolytic and thermal degradation. 

The photo-oxidative degradation of polypropylene and stabilization by hindered amines has been reviewed. A study has appeared of the effect of P-carotene on the photoreactivity of anthracene in hexane solution and a kinetic scheme has been proposed to account for the photochemical and photophysical processes that occur on irradiation at 365 nm. Quenching rate constants have been determined between /S-carotene and singlet oxygen. Some characteristics have been communicated of the sensitized photo-oxidation of abietic acid contained in a vinyl butyl ether-butyl methacrylate-methacrylic acid copolymer. At 400 nm... 

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