engleski

GPC and Structural Analysis of Polystyrene Degradation

The termo-oxidative degradation and photo-oxidative degradation of polystyrene film after long-wave and short-wave ultraviolet irradiation has been studied. An important factor in defining the course of oxidative degradation is the determination of the chain lenght and its distibution, as a result of stimultaneous chain scission and crosslinking reactions. The GPC results show that the termo-oxidative decomposition is followed by an initial drop in molecular mass of the degraded samples due to weak links breaking. The polydispersity corresponds to the presupposed random scission process. In the course of photo-oxidation the change in Mn and Mw is associated with two distinct meshanisms of oxigen consumption. The change reflect the decomposition of primary oxidation products.The change of orginal molecular mass distribution and an important increase in polydispersity indicate a very inhomogeneous degradation. The distribution curves show the growth in low and high molecular fractions. The above-described changes and differences are consequences of specific meshanisms of thermo- and photo-oxidation that have been detemined by means of comparativ spectroscopic experiments. The preferred course of oxidative degradation has been determined in low molecular fractions of polystyrene. Conclusions on the differences between thermo- and photo-oxidative degradation are discussed on the basis of the above date.

polystyrene; degradation

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