SynopsisProlonged heating at temperatures below 140°C. causes only slight changes in the properties of polysulfone. Exposure to ultraviolet light, however, results in substantial changes as evidenced by broad absorption in both the hydroxyl and carbonyl regions of the infrared spectrum, evolution of carbon monoxide and dioxide, decrease in polymer elongation and intrinsic viscosity, and pronounced yellowing. A freeradical mechanism is proposed in which chain scission occurs with the formation of low molecular weight, oxidized fragments as the predominant oxidation products.
SynopsisPolysulfone, polycarbonate, and phenoxy resins were aged under thermal and ultraviolet light conditions. Thermooxidative processes in polysulfone and polycarbonate are of such minor significance as not to impart noticeable losses in these materials below 125°C. I n phenoxy, however, thermal oxidation above 100°C results in rapid deterioration of all physical properties. This probably results from the low glass transition temperature of this polymer. Photo-oxidation rapidly degrades polysulfone. This appears to be a consequence of scission a t the sulfone link. In polycarbonate, however, the only serious result of short-term irradiation is discoloration. For phenoxy resin, crosslinking through reactions a t the hydroxyl group is the principal result of photooxidation. In all processes the bisphenol A portion of the three polymers appears to play only a small role.
The thermal oxidation and photo‐oxidation of poly(2,6‐dimethyl‐1,4‐phenylene oxide) have been examined. Oxidation of the plastic results in the evolution of carbon dioxide, nitrogen and traces of hydrogen, the introduction of considerable crosslinking, and increased absorption in the hydroxyl and carbonyl regions of the infrared spectrum. A free‐radical oxidation mechanism is postulated.
SynopsisSpectroscopic analyses of weathered samples and thermal oxidation of the various phases found in ABS resins indicate that these plastics deteriorate most readily through their polybutadiene component. The change in physical properties and color of these resins with age can be correlated with the decomposition of the polybutadiene-containing phases.
synopsisOne model and two commercial ABS (acrylonitrile-butadiene-styrene) resins have been separated into three polymeric phases: polybutadiene, styrene-acrylonitrile copolymer, and styrene-acrylonitrile copolymer grafted onto polybutadiene. A third commercial ABS resin has been separated into two polymeric phases: styrene-acrylonitrile mpolymer and butadieneacrylonitde copolymer.
ZusammenfassungEin Modell-und awei handelsubliche ABSHarze wurden in 3 Polymerphasen zerlegt: Polybutadien, Styrolacrylnitrilkopolymem und Styrolacrylnitrilkopolymem auf Polybutadien aufgepfropft. Ein drittes handelsubliches ABSHarz wurde in zwei Polymerphasen zerlegt : Styrol-Acrylnitrilkopolymeres und Butadien-Acry~itrilkopol.~eres.
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