蒙脱土改性聚氨酯的结构特性和动态力学性能研究

Structure and Dynamical Mechanical Properties of Montmorillonite Modified Polyurethane

为了探明聚氨酯在纳米层状蒙脱土中的插入情况/结构特性及改性聚氨酯的动力学性能,采用分子模拟技术、X-射线衍射技术及动态热机械分析改性聚氨酯的径向分布函数、平均距离、有序畴尺寸、微观形貌、插层物相、扩散系数及复数模量,以分析改性聚氨酯的结构特性和动态力学性能。不同蒙脱土含量对改性聚氨酯空间结构影响较大,特别是最邻近原子或分子的分布。结果表明:当蒙脱土质量分数低于5.2%时,随着蒙脱土的含量增加,分子链平均距离(最近邻分子位置)减小,分子间相互作用增大,聚氨酯分子链之间的运动能力增强;当蒙脱土质量分数大于5.2%时,蒙脱土自身发生团聚,降低了聚氨酯分子链的运动能力。聚氨酯的均方根位移和扩散系数随着蒙脱土含量的增加而减少,扩散系数基本维持在10-4cm/s数量级。动力学数据表明:蒙脱土的加入会一定程度上弱化聚氨酯的扩散,增加聚氨酯在蒙脱土插层中的位阻。

Organic montmorillonite(MMT)modified caster oil based polyurethane(MMPU)was incorporated into MMT with concentrations of 0%,3.6%,5.2%,and 7.3%respectively by molecular mechanics and molecular dynamics methods to evaluate the effect of MMT on structure change and dynamical mechanical properties of polyurethane composites.These MMPU models were characterized by radial distribution function,mean displacement,radius of gyration,fractional free volume,X-ray diffraction,mean square displacement,and diffusion coefficient at molecular level.Furthermore,the dynamical mechanical properties such as complex modulus and loss factor of MMPU were studied by dynamic mechanical analyzer.The experimental results show that MMT has a huge effect on the structure of MMPU,especially on mean displacement,the interaction force increases with the increasing of MMT contents when the MMT content is lower than 5.2%,and the mean square displacement and diffusion coefficient deduce with the increasing of MMT content.The dynamical mechanical properties indicate that MMT could decrease the diffusion coefficients and increase the positional inhibition.