Synthesis And Reinforce Of New Thermotropic Liquid Crystalline Polymer

In this paper we investigated the synthesis and reinforcement method of crystalline polymer. By trying a new type of catalyst system and optimizing process, we obtain good quality experimental data. Our research provided a mature technique for thermotropic liquid crystalline polymer industrialization, and effective forecast for the synthesis and complex of thermotropic liquid crystalline polymer (TLCP) in the future.1,n-dibronochloropane,as a substituent,was homopolymerized with p-hydroxy benzoic acid to make 1,n-Alkyldioxy-4,4-dibenzoic acid. TLCP which has a good processing properties was synthesized with 1,n-dibronochloropane,4,4-diacetoxy biphenyl and terephthalic acid(TA) by polycondensation method. Introducting the substituent to the polymer chain, the melting point of liquid crystalline polymer was lowered and the proeessing temperature window was expanded. Introducting the substituent effectively solve the problem that polymer decomposite before the formation of liquid crystal phase. Reaction rate and melting viseosity could be well controlled in the later stage of polymerization due to the presence of DODA unit in main chains. The result of statistical analysis on the compositions and melting temperatures of liquid crystalline copolyesters shows that the TLCPs with different melting points can be synthesized by adjusting the mole ratio of monomers,that the TLCPs with different melting points are acquired in the case of different heat distortion temperaturesThe mechanism of TLCPs depends strongly on the operation conditions. The influences of various operating parameters, such as reaction time, reaction temperature, Reaction vessel volume, Vacuum and nitrogen gas flow velocity, were changed with reaction mechanism and rate.The optimum conditions for the synthesis of TLCP has been selected, suitble for its industrialized production.The crystallization and melting behaviors of thermotropic liquid crystalline copolyester were investigated by using differential scanning calorimetry(DSC). The compositions of the all-aromatic thermotropic liquid crystalline polyesters have been characterized by high temperature polarized light microscopy(PLM) and 1H-NMR. The results show that phenomenon of PLM observation as same'as DSC curves:With introduction of the substituent to the polymer chain,the melting point of main chain thermotropic liquid crystalline polymer was lowered, and Tg of TLCP be changed with substituent chain length.The rigidity of the backbone together with the presence of the short length spacer results in high Tg value for TLCP. when chain length is increased,the glass transition will reduce obviously. With introduction of the long chain substituent,we can get good proeessing temperature window range, which will be a research trends.As a new chemical product, ionic liquids(ILs) have attracted significant attention. This paper by introducing new type of ionic liquid as a carrier and the catalyst synthesis, We synthesized a high-performance liquid crystal polymers, to achieve the desired results. Ionic liquids,as a synthesis carrier, has reduced aggregate environmental pollution, improve the conversion rate of polymers and the advantages of reusable which provide a new direction for the future synthesis of thermotropic liquid crystal.The wholly aromatic thermotropic polyesters have excellent overall performance due to their high electrical properties and mechanical properties. GF/TLCP composites have advantages of high strength, high corrosion resistance and insulation. In this research,we prepared a type of aromatic liquid crystal polymer which has full-strength and high modulus. In the later stage of reaction, the chopped fiber was added into the copolymers by in-situ polymerization, obtained GF/TLCP composites with a good performance.