导　　师： 李景庆

学科专业： 080502

授予学位： 硕士

作　　者： ;

机构地区： 天津大学

摘　　要： 本文利用流变学法研究了不同温度条件下POE和PS动态流变条件下的壁滑行为，探讨了壁滑长度b的计算方法，以及壁滑与温度和材料之间的关系；并利用动态流变学方法研究了POE以及POE//PS共混物的非等温结晶行为，探讨了共混物的非等温结晶行为与分散相PS的关系。 类似于“时间-温度叠加”（tTs），根据一定温度时下不同间距时聚合物熔体的动态流变曲线的间距依赖性提出了“时间-间距叠加”（tGs）方法，并用Maxwell模型分析了曲线之间的可叠加性，进而通过平移不同间距下的曲线得到了“主曲线”及各间距下曲线的移动因子，基于零剪切粘度推导出动态流变条件下壁滑长度和移动因子与平行板间距之间的关系式，进而得到熔体的壁滑长度和真实曲线。壁滑行为受温度和材料影响非常明显，一般情况下，在较高的温度条件下，壁滑行为相对较弱，在较低的温度条件下，壁滑相对剧烈，并且当温度低至一定程度时各间距下的曲线无法叠加，这时tGs方法不适用。POE和PS的壁滑行为差别很大，POE的壁滑受温度影响非常强烈，壁滑长度和移动因子都会随着温度降低而明显增大，而PS的壁滑在tGs适用的温度范围内变化较小。 小振幅动态流变条件下的POE和POE//PS的非等温结晶实验表明，在实验采用的线性粘弹条件下，所采用动态频率和应力对其非等温结晶过程无明显影响；由于动态流变条件下的壁滑随温度降低而加剧，造成所得到储能模量等非等温结晶曲线低温部分的重复性较差，误差较大，而高温部分段的重复性较好，误差较小；尽管壁滑对线性粘弹范围内动态流变条件下的储能模量等非等温结晶曲线低温段误差较大，对比纯POE非等温结晶过程的vGP图和POE//PS非等温结晶过程的vGP图时，仍可发现共混物组成对其vGP图的影响比较显著，表明在POE非等温结晶过程产生的结晶结构对于非等温结晶过程中体系粘弹性的影响区别于硬球型的PS分散相，因而两者对储能模量等非等温结晶曲线的影响，因此当采用储能模量等参数进行高分子结晶过程的流变学表征时，不能如悬浮粒子理论中简单地将形成的结晶结构看作“硬球”来处理。 In this thesis, the wall slips of polyolefin elastomer /(POE/) and polystyrene /(PS/) atdifferent temperatures under dynamic shear conditions were investigated. Thedetermination of wall slip length, b and its dependence on temperature and thecharacter of materials were discussed. Then the crystallization behaviors of POE andPOE//PS blends were investigated by dynamic rheology. And the influences of thedispersed PS in the POE//PS blends on their crystallization behaviors were studied. Similar to the well-known “Time-Temperature Superposition”/(tTs/), a “Time-GapSuperposition”/(tGs/) method was established and applied to the obtained angularfrequency sweep data at selected different gaps at certain temperatures, and thesuperposition validity of the data was proved by Maxwell model theoretically. Theshift factors of different curves of storage modulus dependent on angular frequency ofPOE or PS at different selected gaps were obtained by shifting to correspondingmaster curves. On the basis of the relations between the zero shear viscosity and theshift factors, the shift factor was found to be a function of the wall slip length and thegap between the parallel plates. Thus, the wall slip length and the actual experimentalcurves under dynamic shear conditions can be obtained. The results showed that thewall slip showed significant dependence on material character and temperature.Generally, wall slip occurs more heavily at low temperatures while more weakly athigh temperatures, and the tGs was not valid below a certain temperature. The wallslip behaviors of POE is quite different from those of PS and the wall slip of POE ismore heavily dependent on the decreasing temperature while the wall slip of PSchanges a little with the decreasing temperature. The non-isothermal crystallization behaviors of POE and POE//PS under dynamicshear conditions within the linear viscoelastic regions showed that the applied angularfrequency and the dynamic shear stress had no observable influences on thecrystallization behaviors of POE and POE//PS blends. Because the wall slip increasedwith decreasing temperature, the experimental errors of low temperature part of thenon-isothermal crystallization curves were much larger than those of high temperaturepart. Though the errors at low temperatures may be relatively large, from thedifferences between the vGP diagrams of POE and POE//PS blends, the errorsoriginated from wall slip can be ignored and the influences of dispersed PS in POE//PScan be observed easily. It revealed that the dispersed PS shows a different influence on the crystallization behaviors of POE revealed by rheological parameters, such asstorage modulus, complex viscosity and so on, when compared with the formedcrystal structure of POE during crystallization progress. This indicated that the crystalstructure of the crystallization progress cannot be simply handled as hard spheres inrheological characterization of the crystallization progress as in some suspensiontheoretical theories.

关 键 词： 流变学 共混物 壁滑长度 结晶

分 类 号： [TQ317]

领　　域： [化学工程]