【摘要】 采用PVT -10 0分析仪测试了无规聚甲基丙烯酸甲酯 (a -PMMA)在 3 0～ 180℃ ,2 0～ 180MPa下的压力 -体积 -温度 (PVT)曲线。与常压下玻璃化转变是某一点不同 ,高压下a -PMMA的玻璃化出现一个反常的转变区 ,并且随着压力增加 ,该转变区逐渐加宽。PVT实验后 ,a -PMMA的数均和重均摩尔质量均明显下降 ;由DSC测试的Tg和TGA测定的Td 也明显降低 ,说明这一测试的复杂温度和压力历史对样品的结构有显著影响更多还原

【Abstract】 The pressure volume temperature (PVT) data of high molecular weight atactic poly(methylmethacrylate) (a PMMA) were measured by means of PVT 100 analyzer in the pressure range of 20～180 MPa and temperature range of 30～180℃ In the range of high pressure there was an abnormal region of glass transition for a PMMA between the glassy state and rubbery state instead of a single transition point under the normal pressure This glass transition region of the high molecular weight a PMMA became wider with the increase of the pressures It was shown that the molecular weight of the specimen of a PMMA decreased obviously after the PVT measurement The lower values of the glass temperature T g obtained by DSC and the decomposition temperature T d obtained by TGA were found for the specimen after the PVT measurement, which showed the complex thermal history and the pressure ageing of the specimen during the period of the PVT measurement had important effects on the structuresof the sample更多还原