The effects of terpolymer liquid crystalline poly(ester imide) (PPDI) on the structure and properties of its blend with semicrystalline polymer

poly(ethylene terephthalate) (PET) were studied.The PPDI was synthesized by our lab.The blend systems were prepared by melt blending

and the content of PPDI ranged from 0/100 to 10/90. Differential scanning calorimetry (DSC)

wide-angle X-ray diffraction (WAXD) and dynamic mechanical property analysis (DMA) were used to study the crystalline behavior

crystalline structure and dynamic mechanical properties of the blend system

as well as the miscibility of PPDI and PET.Results showed that the addiction of liquid crystalline terpolymer PPDI had strong effect on the crystalline behavior and crystalline structure of PET

which acted as heterogeneous nuclear agents

therefore increasing the initial crystallization point and crystallization rate of PET

and was of benefit to the increase of the degree of crystallinity and the perfection of crystallization.The blend systems show only one glass transition temperature (Tg)

and the Tgs are much higher than the theoretical results calculated by using Fox equation.Dynamic mechanical properties showed that storage modulus of the blend systems was higher than that of PET

and increased with the content of PPDI.These mean that PPDI has a reinforcing effect on PET. The thermal stability of the blend systems is a little higher than that of pure PET.