Study On The Synthesis And Copolymerization Of Unsaturated Liquid Crystalline Polyester

The unsaturated liquid crystalline monomer for P-phenylene di {4- [2- (allyloxy) ethoxy] bebzoate} (p-PAEB)was synthesized in several stages,which was testified by ~1H-NMR and FTIR.The results by POM and WXRD demonstrated that the liquid crystalline phase was smectic and the phase transition temperature range of p-PAEB is 120.5 to 191.5°C.The homopolymer of p-PAEB, and copolymer poly (p-PAEB/St) of p-PAEB with styrene (St), copolymer of p-PAEB with n-butyl methacrylate (BMA) and n-propyl methacrylate (PMA) had been synthesized.by free radical copolymerization.The liquid crystalline behavior and thermal properties of polymers have been studied by polarizing optical microscopic (POM), differential scanning calorimetry (DSC), X-ray diffractometer (XRD), torsional braid analysis (TBA). The results demonstrate that liquid crystalline phase texture and phase transition temperature of copolymers are affected by the composition of liquid crystalline units in copolymers. The POM and XRD reveal that the copolymer of p-PAEB with styrene reveal deformed focal conics texture of smectic phase, but the copolymers of p-PAEB with n-butyl methacrylate (BMA) and n-propyl methacrylate (PMA) are banded texture of nematic phase.The unsaturated polyester formed from 3-methyl-tetrahydrophthalic anhydride (MeTHPA),maleic anhydride,ethylene glycol and styrene was improved by p-PAEB. The morphologic structure and glass transition temperature Tg of improved unsaturated polyester (UP) were investigated by polarizing optical microscopic (POM), torsional braid analysis (TBA), differential scanning calorimeter (DSC) and scanning electron microscopy (SEM). The impact strength was determined. The results shown that p-PAEB had reacted with unsaturated polyester. The p-PAEB was dispersed in the unsaturated polyester in the sea-island structure. It has a higher Tg and impact strength when the content of p-PAEB is about 8%, but the content of p-PAEB is over 8%, the phase separation will generated and the Tg and impact strength will decreased.