Compatible Polycarbonate/Polyamide 6,6 Blends with Fibrillar Morphology

Blends of bisphenol A polycarbonate (PC) and polyamide 6,6 (PA6,6) were prepared directly during the plasticization step of an injection molding process in an attempt to attain both (i) the reinforcement of the blends through fibrillar morphology, and (ii) an adequate compatibilization despite the short processing procedure used. Differential scanning calorimetry and dynamic-mechanical analysis indicated that the blends were made up of a PC-rich phase where some PA6,6 was present and, ruling out a possible degradation, of an almost pure PA6,6-phase. The cryogenically fractured surfaces observed by scanning electron microscopy showed both rather fine particles and larger particles with occluded subparticles. This complex morphology indicates low interphase tension and, therefore, compatibilization, which can be attributed to the presence of PA6,6 in the two phases of the blends. The values of Young's modulus, determined by means of tensile tests, were always synergistic and, in the case of the 25/75 blend, the modulus was even higher than those of any of the two pure components. It appears this could be due to both the highly fibrillar morphology of the dispersed phase, and the significant decrease observed in specific volume. The blends remained ductile throughout the full composition range, which also indicates compatibilization. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 121: 161168, 2011