The Synthesis And Performance Characterization Of Thermotropic Liquid Crystalline Polyurethane Elastomer

In this thesis, the present research and development status of domestic and foreignliquid crystalline polymer (LCP) and liquid crystal polyurethane (LCPU) were mainlyintroduced, meanwhile the characterization of liquid crystalline polymer，the synthesis,classification and influence factors of liquid crystalline polyurethane were analyzedand discussed in detail.In this thesis, I designed different synthesis routes of five system of liquidcrystalline polyurethane, and a total of nine macromolecular polymer of differentstructures were synthesized, meanwhile its structure and properties were characterizedby FT-IR, DSC and POM.The first system, PU1was synthesized by4,4`-diphenol and HDI, theexperimental results show that, biphenyl is good crystal group.PU2, PU3and PU4were synthesized by4,4`-diphenol, HDI and aliphatic diol ofdifferent chain length. The experimental results show that, if the flexible spacer lengthis too long, it will cause the crystal group no longer show liquid crystal. The mobilityof macromolecular polymer increased with the flexible chain length of molecularstructure increased.PU5and PU6were synthesized by4,4`-diphenol, TDI and aliphatic diol ofdifferent chain length. The experimental results show that: the melting point of theLCPU Tm decreased with the length of flexible chain segment increased, Ti of thepolyurethanes changed little. The second system, PU7, PU8, PU9was synthesized by MDI and aliphatic diol ofdifferent chain length. the experimental results show that, PU8and PU9are goodliquid crystal, the crystalline appearance of PU9presents regular rectangle, its liquidcrystal range is20℃.The above experiment results show that, there exists an optimal ratio of rigidinduced crystal group length and flexible spacer length at which the product exhibit thebest liquid crystal.The third system, a new type of side chain liquid crystalline polyurethane PU10was successful synthesized by MDI, ethanol, p-methoxyphenol, acid chloride,triethylamine, benzoyl peroxide (BPO), its phase transition temperature were Tm=93℃, Ti=242℃, the liquid crystal range was149℃.