SynopsisThis paper is devoted to the study of the reactions taking place in molten bisphenol-A polycarbonate-poly(ethy1ene terephthalate) mixtures. The analysis of the reaction products by infrared, proton and nuclear magnetic resonance spectroscopy, and by thermogravimetric analysis. shows that the main reection is an exchange reaction identical to that occurring in bisphenol-A plycarbonate-poly(buty1ene terephthalate) mixtures. However, some other reactions consecutive to this exchange reaction also take place, probably resulting from the instability of the ethylene carbonates produced by transesterification. 'Research

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SynopsisThe kinetic aspects of the bisphenol-A plycarbonatepolyethylene terephthalate exchange reaction are studied. Though the overall mechanism of transesterification is reversible, the kinetics can be treated from a more simple model of two consecutive reactions, due to the decompoeition of the alkyl carbonate formed. T h e values of the kinetic parameters, similar to those obtained for the buphenol-A polycarbonatepolybutylene terephthalate transesterification, suggedt that the moat likely mechanism is a direct ester-ester interchange reaction which can also be catalyzed by additives such as titanium derivatives. PETPPC COFQLYESTER. REACTION 1where Ar-COO, Alk, and Ar' stand, respectively, for a terephthalate, an ethylene, and a bisphenol-A unit. However, the decompotition of aliphatic carbomtes, ati described in a previous paper,' leads to an equilibrium shift towards the right side. If we *Rr;search Associate of the National Fund for Scientific Resear&.

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