ABSTRACT:The effects of addition of the 3rd component of thermotropic liquid crystal polymer (TLCP) on the mechanical properties and structure ofVectra A-reinforced polycarbonate (PC) were studied. The 3rd TLCP was the copolymer of p-hydroxybenzoate (PHB) and ethyleneterephthalate, known as X-7G TLCP. PC, Vectra A, and a small amount of the 3rd TLCP were blended in the molten state, the extrudate of which was cut and injection-molded. The mechanical properties of the blends were improved dramatically by addition of a small amount of the 3rd TLCP component. SEM revealed that the blend systems were always phase-separated, even after injection-molded, and the fibrils of Vectra A in the injection-molded blends became finer and longer in the presence of the 3rd TLCP. FT-IR indicated that no special chemical reaction took place between the TLCP and PC. The dynamic viscoelastic analysis indicated that the addition of the 3rd TLCP component had almost no effect on the thermal endurance of the blends. X-Ray diffraction analysis showed that the orientation ofVectra A fibril in the blend became higher when the 3rd TLCP was added, which Jed to the great improvement of the mechanical properties. Based on the assumption of additivity law, the fibril modulus was evaluated and found to be in the same order as the orientation evaluation by X-ray diffraction. The thinning of fibrils by addition of the 3rd TLCP component was discussed based on the crystallization kinetics of rodlike molecules.KEY WORDS Polycarbonate/ Liquid Crystal/ Ternary Blends/ Mechanical Properties / Morphology / Crystallization Kinetics / As one of the applications of the thermotropic liquid crystal polymers (TLCP), the blends of engineering plastics and TLCP are promising the improvement of mechanical and thermal properties due to the reinforcing function and thermal endurance of TLCP. There have been many engineering and scientific reports on this subject. Kiss 1 suggested a concept of"in situ composite," emphasizing the fact that the TLCP reinforcement could be formed "in situ" during processing. Isayev et al. 2 called them as "self-reinforced melt processable polymer composite". According to Brostow et al. 3 the composite could be classified into two kinds: one was the traditional fiber-reinforced composite, being classified as a heterogenous composite; the other was the molecular composite, such as selfreinforced plastics and the molecular composite in the strict meaning suggested by Takayanagi. 4 From many papers reported on the blends of the engineering plastics and TLCP, one can find two important facts: such blend systems are usually phase-separated and

ABSTRACT:The effects of addition of the 3rd component of thermotropic liquid crystal polymer (TLCP) on the mechanical properties and structure of Vectra A-reinforced poly(butylene terephthalate) (PBT) were studied. The 3rd TLCP was the copolymer based onp-hydroxybenzoate (PHB) and ethylene terephthalate, known as X-7G. PBT, Vectra A, and the third TLCP were blended in the molten state, the extrudate of which was cut and injection-molded. The mechanical properties of the blends were improved by the combination of the two kinds ofTLCP. The dynamic viscoelastic analysis indicated that the thermal endurance of the ternary blends were enhanced when Vectra A was used as a major TLCP reinforcement. SEM revealed that both the binary and ternary blends were phase-separated, and the introduction of the 3rd component of TLCP was profitable for TLCP to form finer fibrils at the skin part of the sample. X-Ray diffraction analysis showed that the orientation of Vectra A fibril in the blend was raised by the addition of the 3rd TLCP, resulting in the improvement of the mechanical properties of the ternary blends. The conclusions obtained in this paper agreed with those reported in our previous paper.KEY WORDS Poly(butylene terephthalate) / Thermotropic Liquid Crystal / Ternary Blends/ Mechanical Properties/ Morphology/ X-Ray Diffraction Analysis/ In our previous paper, 1 we reported the effects of the 3rd component of TLCP on the mechanical properties of Vectra A (VA)-reinforced polycarbonate (PC). The mechanical properties of PC/VA binary blend were improved dramatically by addition of a small amount of the 3rd component of TLCP composed of PHB and PET, which was a X-7G type semi-aromatic TLCP, Rodlan of the trade name of Unitika Co. The effects were ascribed to the enhancement of orientation of TLCP ( mainly VA) in fibril, which was supported by the X-ray diffraction and the theoretical analysis based on a two-phase blend model and the SEM observation.In this paper, we continued to combine the both advantages of Vectra A and Rodlan and blended them with the matrix resin of poly-(butylene terephthalate) (PBT), forming a ternary blend system. Kimura and Porter 2 reported the thermal properties and the dynamic mechanical measurements of the binary blend of PBT/X-7G prepared by a solution precipitation method and found that both components were compatible due to the molecular interaction between PBT and the

ABSTRACT:The effects of molecular weight of nylon 6 on the phase separation of nylon 6 in the molecular composites of nylon 6/poly(p-phenyleneterephthalamide) (PPTA) kept at 240°C and their mechanical properties related to molecular dispersity of PPTA have been studied on the coagulated and hot-pressed film. Crystallization of nylon 6 in the composites was studied by infrared spectroscopy, differential scanning calorimetry and X-ray diffraction. The crystallinity of nylon 6 was lost in the presence of PPT A when the PPT A content exceeds 50 wt% through all the range of molecular weight of nylon 6. The N-H stretching bands characteristic of PPTA and nylon 6 united to show a sharp single peak for the hot-pressed molecular composite for nylon 6 with M W = 2.6 X 10 5 , indicating the interruption of aggregation ofPPT A molecules. The tensile modulus and strength were monotonously increased with increasing molecular weight of nylon 6 and weight fraction of PPT A in the composites. The improved dispersity of PPT A molecules gives outstanding mechanical properties to the molecular composite. The film strength was 170 MPa and the modulus was 12GPa for the hot-pressed composite film of IOwt% nylon 6 using its highest molecular weight.KEY WORDS Poly(p-phenyleneterephthalamide) / Nylon 6 / Phase Separation / FTIR / Molecular Composite / Modulus / Strength /