TOUGHENING OF POLY(BUTYLENE TEREPHTHALATE) WITH CORE-SHELL IMPACT MODIFIERS DISPERSED WITH THE AID OF POLYCARBONATE

Commercial emulsion-made impact modifiers with a shell of poly(methyl methacrylate) (PMMA) chains grafted onto a rubber core, either acrylat e or butadiene based, cannot be adequately dispersed in a matrix of po ly(butylene terephthalate) (PBT) to achieve useful toughening. However , it is known that tough materials can be achieved when these blends a lso contain polycarbonate (PC). It is demonstrated here that 10 wt% or less of PC greatly facilitates the dispersal of such core-shell impac t modifiers in a PBT matrix and leads to tough blends even at low temp eratures. It is known that PC wets PBT and PMMA better than PBT and PM MA wet each other, which allows the PC to act as a dispersing agent fo r these impact modifier particles in the PBT matrix. The morphology an d mechanical properties of ternary blends where PC is a major matrix c omponent rather than simply a dispersing agent are also examined.