Thermotropic liquid crystalline VHE terpolyesters made from vanillic acid (V),p-hydroxybenzoic acid (H) and poly(ethylene terephthalate) (E) were studied by 400 MHz NMR spectra, wide angle X-ray diffraction,scanning e...Thermotropic liquid crystalline VHE terpolyesters made from vanillic acid (V),p-hydroxybenzoic acid (H) and poly(ethylene terephthalate) (E) were studied by 400 MHz NMR spectra, wide angle X-ray diffraction,scanning electron and polarizing microscopes.It was found that the VHE terpolyesters had random sequence distribution.The VHE terpolyester films exhibited highly oriented fibrillar structure.展开更多
In a previous study we focused on the synthesis of new family of unsaturated copolyesters and terpolyesters by interfacial condensation polymerization. Here, in this study as complementary work of physical characteriz...In a previous study we focused on the synthesis of new family of unsaturated copolyesters and terpolyesters by interfacial condensation polymerization. Here, in this study as complementary work of physical characterizations, we focused on the morphological features using X-ray and SEM investigation. Further, the mechanical properties of solid polymers were also studied by a new technique echo-pulse using ultrasonic impulses. This technique was used for solid polymers to determine the elastic moduli involving, Young’s modulus, shear modulus, bulk modulus and micro-hardness modulus. The statistical relation between different kinds of copolyesters and terpolyesters with Poisson’s ratio (υ) and micro-hardness were shown. The dielectric constant (?) and the electrical resistance (Rp) of the solid copolyesters and terpolyesters including aliphatic, aromatic and azo group in the main chain have been studied at room temperature. Moreover, the relation between frequency and dielectric constant for the selective polymers has been also illustrated.展开更多
Nine thermotropic liquid crystalline terpolyesters based on vaniUic acid(V), p-hydroxybenzoic acid(H) and poly(ethylene terephthalate)(E) were investigated by thermogravimetry to ascertain their thermostability and th...Nine thermotropic liquid crystalline terpolyesters based on vaniUic acid(V), p-hydroxybenzoic acid(H) and poly(ethylene terephthalate)(E) were investigated by thermogravimetry to ascertain their thermostability and the kinetic parameters for thermal degradation. Overall activation energy data of the degradation had been calculated over the range 5 ～ 70% weight loss. The temperatures and the activation energy of the degradation lie in the ranges of 384 ～ 394 ℃ at a heating rate of 1℃/min and 176 ～ 205 KJ/mol at the weight loss of 5%, respectively, which suggests that the terpolyesters have good thermostability.展开更多
文摘Thermotropic liquid crystalline VHE terpolyesters made from vanillic acid (V),p-hydroxybenzoic acid (H) and poly(ethylene terephthalate) (E) were studied by 400 MHz NMR spectra, wide angle X-ray diffraction,scanning electron and polarizing microscopes.It was found that the VHE terpolyesters had random sequence distribution.The VHE terpolyester films exhibited highly oriented fibrillar structure.
文摘In a previous study we focused on the synthesis of new family of unsaturated copolyesters and terpolyesters by interfacial condensation polymerization. Here, in this study as complementary work of physical characterizations, we focused on the morphological features using X-ray and SEM investigation. Further, the mechanical properties of solid polymers were also studied by a new technique echo-pulse using ultrasonic impulses. This technique was used for solid polymers to determine the elastic moduli involving, Young’s modulus, shear modulus, bulk modulus and micro-hardness modulus. The statistical relation between different kinds of copolyesters and terpolyesters with Poisson’s ratio (υ) and micro-hardness were shown. The dielectric constant (?) and the electrical resistance (Rp) of the solid copolyesters and terpolyesters including aliphatic, aromatic and azo group in the main chain have been studied at room temperature. Moreover, the relation between frequency and dielectric constant for the selective polymers has been also illustrated.
基金Project supported by the National Natural Science Foundation of China.
文摘Nine thermotropic liquid crystalline terpolyesters based on vaniUic acid(V), p-hydroxybenzoic acid(H) and poly(ethylene terephthalate)(E) were investigated by thermogravimetry to ascertain their thermostability and the kinetic parameters for thermal degradation. Overall activation energy data of the degradation had been calculated over the range 5 ～ 70% weight loss. The temperatures and the activation energy of the degradation lie in the ranges of 384 ～ 394 ℃ at a heating rate of 1℃/min and 176 ～ 205 KJ/mol at the weight loss of 5%, respectively, which suggests that the terpolyesters have good thermostability.
