含磷全芳族热致液晶共聚酯的合成及热性能

Synthesis and Thermal Behavior of Phosphorus-containing Thermotropic Wholly Aromatic Copolyesters

全芳族热致液晶聚酯因其优良的力学性能、热稳定性及较低的熔融粘度而倍受关注,是当今最有前途的特种高分子材料之一.但是,全芳族聚酯的刚性结构使其熔点较高,难以加工,因而通过分子设计制备熔点较低的热致全芳香族聚酯液晶成为研究的热点.在主链型热致液晶高分子的分子设计中,通常采用共聚或在高分子链中引入取代基、柔性链段、扭结成分等方法来达到降低聚合物相转变温度的目的[1～6].

A series of flame retardant thermotropic wholly aromatic copolyesters were derived from acetylated 2\|(6\|oxido\|6\%H\%\|dibenz<c,e><1,2>oxa phosphorin\|6\|yl)\|1,4\|dihydroxy phenylene(DOPO\|HQ), \{\%p\%\|acetoxybenzoic\} acid(\%p\%\|AHB), terephthalic acid(TPA) and isophthalic acid(IPA) by melting polycondensation. The structure and basic properties of polymers, such as glass transition temperature(\%T\%\-g), melting temperature(\%T\%\-m), thermal stability, and liquid crystallinity were investigated by FTIR, elemental analysis, differential scanning calorimetry(DSC), thermogravimetry analysis(TGA), and thermal polarized optical microscope. The copolyesters have relative high \%T\%\-g values which range from 456 to 465 K. The \%T\%\-m obtained from DSC curves(P\|20 and P\|25) and initial flow temperatures(\%T\%\-f) observed on hot\|stage polarizing microscope are from 544 to 568 K. The decomposing temperatures(\%T\%\-\{d50%\}) in nitrogen range from 704 to 735 K, and char yields at 923 K are 41%~52%. All the copolyesters, except P\|40, are thermotopic and nematic.