PROCESSING MORPHOLOGY CORRELATIONS IN POLY(BENZOATE-CO-NAPHTHOATE) LIQUID-CRYSTALLINE POLYMERS

The molecular orientation and disclination defects in injection molded bulk samples of liquid crystal polymer's have been revealed by transm ission electron microscopy (TEM). Using a recently optimized lamellar decoration and etch technique for use with poly(benzoate-co-naphthoate ), we have studied in detail the skin-core morphology produced by real istic injection molding processing. In the skin, the director is obser ved to be highly aligned along the flow direction, and the defect dens ity is very low (10 cm-2). In the core, however, the defect density is six orders of magnitude greater, and the director lies predominantly in the plane defined by the flow and neutral directions. The flow duri ng processing is turbulent, giving rise to distinct morphological feat ures and disclination clusters. When the material is filled at 20% vol ume fraction with long glass fibers, the molecular and filler orientat ions are nearly parallel. Dimensional precision also correlates with t he morphology and improves with increasing core fraction.