Polycarbonate/TLCP blends: Compatibilization, barrier and bond characteristics

Blends of polycarbonate and Vectra(TM) liquid crystal polymer, at 88/12 wei ght ratios, have been prepared at temperatures ranging from 240-340 degrees C. Inverse gas chromatographic data show that the bulk penetration of non- polar as well as polar vapors is significantly lowered in blends prepared a bove about 300 degrees C. IGC data also report a surface excess of the TLCP component which was found to have a lower dispersion surface tension than the host polymer. The bond strength of PC/TLCP lap shear joints prepared ov er the noted temperature range increases monotonically with temperature, bu t a pronounced added change occurs in the 290-300 degrees C interval. The r esults are consistent with earlier reports that at T greater than or equal to 300 degrees C PC and TLCP can interact only through dispersion (L/W) for ces. Accordingly, it is apparent that a processability window exists for th e blends in which the compatibility of the host and added polymer is enhanc ed, with repercussions on diffusion and bond characteristics.