60PHB／PET热致液晶共聚酯的流动特征相转变及热处理的影响

在２９０℃下经熔融共聚制得６０ＰＨＢ／ＰＥＴ热致液晶共聚酯。用毛细管流变仪测定流动性能，表明此共聚酯为切力变稀流体；其非牛顿指数、屈服应力在２６０℃均有突变。结合ＤＳＣ，ＤＬＩ，ＴＯＴ等研究，共聚酯在２５５～２５８℃为ＰＨＢ微晶向向列型液晶转变点。流变特征与相态有关。经高温处理（＞２６０℃）的共聚酯熔体在较低温度下呈保持高温流动特征。而经不同温度热处理后冷却样品，其相转变热焓、相转变温度均随热处理温度的增加而增加，尤其是在２６０℃以上热处理后冷却样品，其相转变热焓增加较大，而２８０℃以上热处理后冷却样品的相转变热焓达到最大值。

FLOW CHARACTER PHASE TRANSITION AND EFFECT OF HEAT-TREATMENT ON 60 PHB/PET THERMOTROPICS LIQUID CRYSTAL COPOLYESTER

PHB/PET thermotropics liquid crystal copolyester is prepared by melt copolymerization at 290℃,whose flow behaviour is measured by capillary Rheometry at 250,260,280,300℃ respectively. The copolyester melt is a shearthing fluid,whose non-Newtown index,yield stress shows a transition at 260℃. The phase transition from PHB-rich phase to nematic liquid crystal at 255～258℃ has been identified by DSC,DLI,TOT,which is related to flow character. The effect of heat-treatment temperature on the flow character and phase transition of 60 PHB/PET copolyester is shown to be:The flow character of the copolymer below 250℃, which are heat-treated above 260℃,is still similar to that above 260℃. The phase transition temperature and entropy increase with the increasing of heat-treatment temperature. A clear trump is shown at 260℃.