Ultimate properties of polycarbonate blends: Effects of inclusion plastic deformation and of matrix phase continuity

Tensile energy to break (TEE) of polycarbonate (PC) blends has been increased by exploiting (i) the plastic deformation of dispersed or co-continuous brit-tie polymer(s) and (ii) higher matrix phase continuity in ternary blends with two dispersed minority components. Monotonic dependence of yield strength on blend composition and micrographs of drawn specimens concurrently evidence a strong interfacial adhesion sufficient for transmission of yield and/or break stress. Good adhesion at created interfaces, was achieved through partial miscibility of PC with other components, i.e., poly(styrene-co-acrylonitrile) (PSAN) and poly(styrene-co-methyl methacrylate) (PSMMA), which was evaluated from the shifts of the glass transition temperatures of conjugate phases. Binary and ternary blends with PC contents higher than 35% show extensive plastic deformation after yielding. TEE and strain-at-break of ternary blends with 50% or 40% PC pass through a maximum at compositions with equal fractions of PSAN and PSMMA, which is in qualitative accord with model calculations of the matrix phase continuity. Thus, the blend PC/PSAN/PSMMA = 40/30/30 preserves 70% of TEE of neat PC.