Effect of LCP Inclusion on Processability and Thermal Stability of Glass Fiber-reinforced Hybrid Composites
Shing-Chung Wong, Sreekumar Pisharath, Xiao Hu
North Dakota State University
USA
Keywords: Processability, Morphology, Hybrid
A series of studies were conducted to investigate the effect of LCP inclusion on the processability of short glass fiber reinforced toughened nylon 6,6. The objective was to identify the role of each component phase and obtain composite synergism arising from a multi-component system. It was found that a hybrid composite offered superior processability over the glass fiber reinforced polymers alone. The total torque in melt mixing increased with short glass fiber addition but decreased with an increase in LCP content. The improved processability of the hybrid composite was ascribed to the orientation of LCP domains in the direction of flow. Cryofractured extrudates were examined using scanning electron microscopy (SEM). Morphology observed from fractographs indicated LCP elongation in strengthened matrices.
Hybridization also introduced new thermal-morphological interactions among component phases. The thermal and crystallization behaviors were studied by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), SEM, and wide angle X-ray scattering (WAXS). DSC results showed that crystallinity of glass fiber reinforced toughened nylon 6,6 was decreased by LCP addition particularly in the 5-10 wt% LCP range. DMA results indicated that the maximum miscibility between the blended components was in the 5 wt% LCP composition and the miscibility decreased with increasing LCP content. The possible role of elastomer acting as a compatibilizer was critically assessed. It was also observed that the 10 wt% LCP composition showed predominantly amorphous character using WAXS. LCP hybridization increased the interplanar spacing of the hydrogen bonded sheets of the nylon crystals rather than the spacing between the hydrogen bonded chains making the sheets more mobile than the chains.