【作者】 李江；

【导师】 傅强；

【作者基本信息】 四川大学 ， 材料学， 2006， 硕士

【摘要】 将高分子成型加工同高分子物理相结合，特别是成形加工中的形态控制，是目前国际上高分子科学研究的热点之一。本论文主要针对聚丙烯共混体系，在注塑过程中通过引入动态剪切场，改变各加工参数等方法，使熔体在不同的剪切场、温度场下冷却成型，以实现对共混物相形态的有效控制。通过制品形态结构的表征，对共混物的形态发展，相容与相分离、取向和结晶结构以及对应的宏观力学性能进行了深入研究。主要研究结果如下： (1)共混物中熔体的相容性对制品的形态结构具有重要影响。我们选用四种不同结构和相容性的弹性体aPP、POE、EPDM、EVA与iPP共混，由动态粘弹实验表征其与基体PP的相容性好坏依次为aPP、POE、EPDM、EVA。动态保压注射成形得到取向的样品，应用PLM，SEM，DSC，2W-WAXD等表征各体系的相形态和结晶、取向结构。在不相容的PP／EVA体系中，我们发现了更大的粒子的变形以及基体片晶的取向，而在相容性较好的PP／aPP体系中，除了相区尺寸小之外，其粒子的变形很小，基体的取向也非常的微弱。这基本上可以归结于共混中分子缠结的作用。 (2)对于不同的加工温度、注射速度以及模温等注射条件下，聚丙烯(PP)／乙烯-辛烯共聚弹性体(POE)共混物(固定配比(60／40))下的多层次相形态结构和力学性能做了深入研究。在所选加工条件下，制品最外层不含橡胶粒子，而取向的POE粒子出现在次表层，并且相区尺寸很大。从过渡层到芯层，我们观察到了分散相尺寸逐渐变大而且和加工条件密切相关，并最终有可能发展成为双连续相形态。实验表明，较高的加工温度、低注射速度以及较低的模具温度使得分散相相区尺寸减小。拉伸强度和冲击强度对于加工条件并不敏感，但是对于低的冲模速率来讲，其拉伸和冲击强度相对于其他样品都达到了一个最大值。从结晶学以及流变学的观点出发，我们认为皮层的形成可能是由于基体快速结晶从而排斥橡胶粒子于晶格之外以及第一法向应力差的影响所导致的。更多还原

【Abstract】 Studying the physical problem during the polymer molding process, combining the polymer physics and polymer molding process, and the research on the control of the morphology of polymer blends are one of the hot research fields in the polymer science at present. In this work, PP blending system is the research point. The morphology structure was controlled via the dynamic shear field and different processing conditions and its structure was deeply studied. The main results are listed here:First, we study the effect of miscibility on phase morphology and orientation of is tactic polypropylene (iPP) blends under shear stress was investigated via dynamic packing injection molding (DPIM). The miscibility’s of iPP blended with other polymers, namely, atactic polypropylene (aPP), octane-ethylene copolymer (POE), ethylene-propylene-diene rubber (EPDM) and poly (ethylene-co-vinyl acetate) (EVA), have been first studied using dynamic mechanical analysis (DMA). These blends were subjected to DPIM, which relies on the application of shear stress fields to the melt/solid interfaces during the packing stage by means of hydraulically actuated pistons. The phase morphology, orientation and mechanical properties of the injection-molded samples were characterized by SEM, 2D WAXS and Instron. For immiscible iPP/EVA blends, a much elongated and deformed EVA particles and a higher degree of iPP chain orientation were observed under the effect of shear. However, for miscible iPP/aPP blends, a less deformed and elongated aPP particles更多还原