Studies of Nylon/PC blends

Abstract

This report presents an investigation of the interchange reactions and morphology in a partially miscible blend composed of bisphenol-A-polycarbonate and Nylons with and without polycaprolactone by the use of DSC, SEM and DMTA.

DSC results show that NY6 is faster than NY66 in interchange reaction with PC and incorporation of polycaprolactone improves the compatibility of NY66 with PC. At longer heat treatment time, Tgs of both component polymers approach each other, which suggests that interchange reaction occurs between two immiscible homopolymers, making them homogenize and resultant block and graft copolymers serve as a link between two polymers. The general features of incompatible and biphasic system were displayed by Scanning Electron Microscopy in the morphology of the NY66/PC blends without polycaprolactone. In Nylon-rich blends, there is less gap between globule PC and matrix NY66, while PC-rich blends have a clear gap between the boundaries of NY66 and PC. The formation of voids can be explained considering the different volume contraction occurring during the thermal transitions of the two polymers. Polycaprolactone changes the morphology of NY66/PC blend, in which distributed globule sizes become small and deviation of the globule sizes is decreased. This implies that polycaprolactone serves as a thermodynamic plasticizer controlling the particle size, and it can reduce the melt viscosity of the PC. Two kinds of mode, 3-point bending and tensile mode, were used in Dynamic Mechanical Thermal Analysis. Two Tgs are present in most compositions except those between 20/80 and 5/95 (NY66/PC wt%), in which Tg of NY66 was not detected. Tg of PC was decreased largely in 95/5. These results may explain immiscibility in most compositions and partial miscibility of each abundant proportion of component, which maybe enable an interchange reaction. Polycaprolactone shows a huge effect in lowering Tgs of NY66/PC blend.