PROCESSING-STRUCTURE-PROPERTIES RELATIONSHIPS IN BLENDS WITH THERMOTROPIC LIQUID-CRYSTALLINE POLYMERS

In this paper the effect of the inclusion of thermotropic liquid crystalline polymers (TLCP) in thermoplastic polymers is analyzed, with due attention to similar studies reported in the literature. Numerous results relative to TLCP containing blends are considered in terms of structure development in typical processing operations like extrusion and fiber spinning. Several systems have been studied in order to emphasize that different effects can be obtained as regards processing and mechanical properties of the host matrices. As for rheological aspects, it has been verified that TLCP can be considered as effective flow aids, even at low concentrations. The addition of a low percentage (5 to 10 %) of a TLCP with a viscosity lower than that of the matrix produces a significant reduction (25 to 40 %) in the blend viscosity. Moreover, mechanical results have shown that an improvement of the matrix rigidity can be obtained, especially at high percentages of TLCP (30 %), under processing conditions where a highly extensional flow prevails. However, a decrease in the ultimate elongation of the matrices has been found in all systems where a poor adhesion between the two phases exists.