PA1212和PA1212-b-PTMG熔体粘弹行为及PA1212分子量测定

【作者】 黄瑞杰；

【导师】 刘民英；

【作者基本信息】 郑州大学 ， 材料学， 2005， 硕士

【摘要】 本文采用动态流变和蠕变及恢复的方法,研究了均聚尼龙1212和热塑性弹性体嵌段共聚物尼龙1212-b-聚四氢呋喃(PA212-b-PTMG)熔体的粘弹行为,考察了温度、分子量、聚合物结构等对其熔体粘弹性的影响,获得了尼龙1212熔体粘弹特征和PA212-b-PTMG嵌段聚合物熔体微相分离的信息。同时测定了尼龙1212分子量和分子量分布,计算出特性粘数与分子量之间关系Mark-Houwink方程中的K、α值。主要得出结论如下: 1.尼龙1212的线性粘弹区较宽,受分子量的影响较小。在线性粘弹区,熔体的动态模量均随PA1212分子量的增加而提高,因分子极性和缠结程度不同,储能模量G’对振荡频率在低频区存在不同程度的缓增现象,耗能模量G”在高频区偏离线性关系,动态粘弹特征偏离Maxwell模型方程。PA1212熔体为假塑性流体,随分子量增加,非牛顿性增强。在非线性粘弹区,PA1212熔体蠕变和恢复试验表明,随PA1212的分子量增加蠕变量减小,形变恢复比例增加。对尼龙1212的粘弹性可以进行时-温叠加,时-温叠加的平移因子α_T与温度的关系符合Arrhenius方程,所得的平移活化能与熔体的粘流活化能相符。由试验所得粘弹数据计算松弛时间谱,松弛时间谱峰位置随温度升高,逐渐向短松弛时间区偏移。 2.合成的PA1212-b-PTMG的线性粘弹区比均聚尼龙1212缩小。logG’～logG”图中,随着PA1212嵌段分子量的增加,曲线具有温度依赖性,说明熔体呈现出微相分离状态。对粘弹数据进行时-温度叠加出处理,熔体的耗能模量G”具有很好的叠加性,而G’时-温叠加失效。在低频率区,随硬段PA1212分子量增大,熔体稳定性提高,动态粘度与频率关系具有Cross方程函数拟合性.表现为的假塑性流体特征,时-温叠加对不同温度下的复合粘度失效。温度扫描中,PA1212-b-PTMG的活化能均小于尼龙1212,耐高温性能降低。蠕变试验中,随PA1212-b-PTMG分子量的增加,形变量、蠕变柔量减小,蠕变粘度提高。随PA1212嵌段分子量增大,熔体松驰峰位置向短时间区移动,从而证明随PA1212嵌段分子量增大,体系微相分离程度增大。更多还原

【Abstract】 The effects of temperature, molecular weight and the structure of polymers on the viscoelastic behavior of nylonl212(PA1212) bulk homopolymers and the block copolymers nylon and poly(tetramethylene glycol)(PA12l2-b-PTMG) were investigated using the dynamic rheology, creep and recovery test. The information about the viscoelastic characters of PA1212 and the microphase separation of the PA1212-b-PTMG were obtained. Meanwhile the method of measuring the molecular weight for nylon 1212 were explored and some results were obtained. The main conclusions of the dissertation as following: .1. PA1212 presents a wide linear visicoelastic region that is independent the molecular weight. The dynamic storage moduli(G’ ) of the PA 1212 increase with the molecular weight increasing, and increases lentamente in the low frequency range for the small molecular weight of PA1212. The loss moduli (G" ) depart from the linear relationship with the frequency in the high frequency range. And the dynamic viscoelastic behavior of PA1212 could not be well desctibed with the Maxwell model. The results show that the PA1212 melt is pseudoplastic fluid and its non-Newton index n reduces with the molecular weight increasing. The creep and recovery of the PA 1212 was tested in the non-linear range. The creep strain becomes smaller and the ratio of its recovery strain increase as the molecular weight increasing. The time-temperature superposition (TTS) deal with the viscoelastic characters of the PA1212 at different temperatures. The relation between shift factor and temperature is fit for Arrhenius function and the shift active energy is equivalent to the flow active energy. The peak of relaxation spectrum shifts to the short time region with temperature increasing.2. The linear viscoelastic range of the PA1212-b-PTMG is narrower than更多还原