SHEAR AND ELONGATIONAL VISCOSITIES OF A THERMOTROPIC LIQUID-CRYSTALLINE POLYMER AND ITS BLEND WITH POLYCARBONATE

The shear and elongational viscosities of a thermotropic liquid crystalline polymer (LCP), polycarbonate (PC), and their 20% LCP/80% PC blend, were studied using a capillary rheometer. The investigation focused on experimental studies using two sets of capillaries. The first set comprised capillaries having a converging entrance followed by a cylindrical section. The second set, "zero length" set, included capillaries having only the converging section. In the two sets various entrance angles were used. Experimental results have shown that shear viscosities and entrance pressures are practically independent of the entrance angles. The entrance pressure drop was small in the case of PC and reached 50% of the total pressure drop for LCP. The elongational viscosities of the LCP were found to be higher than those of the PC in the elongational-rate range studied, while shear viscosities of the LCP were higher in the lower shear rate region and lower in the higher shear rate region compared to those of PC. This was attributed to the orientability of LCP in elongational and shear flows.