Microhardness of condensation polymers and copolymers. 1. Coreactive blends of polyethylene terephthalate and polycarbonates

11 pags., 4 figs., 1 tab.The microhardness of coreactive blends of polyethylene terephthalate (PET) and bisphenol A polycarbonate (PC) was investigated over the whole range of compositions. The occurrence of one single glass transition temperature (Tg) step in the differential scanning calorimetry (DSC) curves indicated that intensive chemical interactions had taken place during melt blending resulting in formation of copolycondensates with dominating random sequential order. The parallel decrease of microhardness (H) and of Tg with increasing PET content in the blends has been ascribed to the formation of new copolymer molecules enriched in the component characterized by lower H and Tg values. It is emphasized that such noncrystallizable copolymers offer the possibility to evaluate the intrinsic contribution of the repeating units to the H and Tg characteristics of copolymers with various compositions and sequential orders.The authors are grateful to DGICYT, Spain (Grant PB94-0049), for the support of this investigation. One of us (S.F.) deeply appreciates the tenure of a sabbatical grant from DGICYT, as well as the hospitality of Instituto de Estructura de la Materia, Madrid, Spain