Influences of reactive compatibilization on the structure and physical properties of blends based on thermotropic liquid crystalline polyester and poly(1,4-cyclohexylenedimethylene terephthalate)

We report the effects of reactive compatibilization on the morphology, microstructure, and physical properties of thermotropic liquid crystalline polyester/poly(1,4-cyclohexylenedimethylene terephthalate) (TLCP/PCT, 75/25 by wt%) blends, which are fabricated via melt-compounding in the presence of different catalyst types and contents. Among three different catalysts, titanium butoxide (TBT) is found to be most effective in the reactive compatibilization of TLCP/PCT blends, which is confirmed by SEM images. FT-IR spectroscopic analysis reveals the formation of copolyesters by catalyst-induced transesterification between TLCP and PCT components during melt-compounding with 0.5 and 1.0 phr TBT loadings. Nonetheless, X-ray diffraction analysis confirms that the crystal structures of TLCP/PCT blends are not affected by reactive compatibilization. The melting and crystallization transition temperatures of the PCT component in the compatibilized blends decrease owing to the shortening of crystallizable PCT segments by the transesterification. TGA data show that the residue at 800 degrees C increases for the blends melt-compounded with higher TBT catalyst loadings. The shear moduli and complex viscosity of compatibilized TLCP/LCP blends at a melt state are found to be even higher than neat TLCP and PCT. Although the elastic storage moduli of compatibilized TLCP/PCT blends are slightly lower than neat TLCP, they are far higher than neat PCT.

Automated summary

Reactive compatibilization using titanium butoxide (TBT) was found to be the most effective method for improving the morphology and physical properties of TLCP/PCT blends. FT-IR spectroscopic analysis confirmed copolyester formation through catalyst-induced transesterification. Despite the decrease in crystallization transition temperatures, the residue at 800 degrees C increased for blends with higher TBT loadings, indicating improved thermal stability. The shear moduli and complex viscosity of compatibilized TLCP/LCP blends were higher than neat TLCP and PCT, showing enhanced mechanical properties after reactive compatibilization.