The crystallization behavior of blends of thermotropic liquid crystalline polymers

This work was concerned with how the crystallization temperature of a therm otropic liquid crystalline polymer (TLCP) was lowered when blended with a s econd TLCP, with both TLCPs believed to be composed of various ratios of te rephthalic acid, 4-hydroxybenzoic acid (HBA), hydroquinone, and hydroquinon e derivatives. Specifically, HX6000, with a melting temperature of 332 degr ees C, was melt blended with HX8000, with a melting temperature of 272 degr ees C. Measuring the complex viscosities of the melt blends as they were co oled showed that a linear relationship between composition and solidificati on temperature existed. Studying the blends using differential scanning cal orimetry (DSC) demonstrated that the crystallization temperature was lowere d by addition of HX8000, as well as by using faster cooling rates. Dynamic mechanical analysis revealed that the storage and loss moduli decreased wit h the addition of HX8000 and the moduli declined sharply at lower temperatu res relative to neat HX6000. Additional testing was performed to help under stand this behavior, with the results suggesting that the TLCPs reacted wit h one another when the test samples were injection molded. (C) 1999 Elsevie r Science Ltd. All rights reserved.