【作者】 吴德峰；

【导师】 史铁钧；

【作者基本信息】 合肥工业大学 ， 材料科学与工程， 2002， 硕士

【摘要】 聚丙烯（PP）作为一种通用塑料具有较好的综合性能，但其较高的低温脆性大大限制了它地进一步推广应用。针对PP的增韧增强改性的研究很多，主要集中在橡胶或弹性体增韧、无机刚性粒子增强等方面。但橡胶增韧聚丙烯，会使材料刚度、强度下降；采用填料增强，韧性又会下降；近年来出现了通过熔融插层制备的插层型聚丙烯／粘土纳米复合材料，其强度、韧性均有所提高，但仍未达到理想值。 本课题首先采用高活性的接枝单体丙烯酰胺在蒙脱土片层间插层聚合的同时对PP基体进行接枝反应，即原位接枝插层聚合，制备出蒙脱土片层完全剥离的母料；然后将母料以适当比例与PP共混加工，采用这种具有创新性的“两步法”成功制备了剥离型聚丙烯／蒙脱土纳米复合材料。该复合材料的拉伸强度最大可达42.41Mpa，较之纯PP增加了26％，缺口抗冲强度最大达10.50kJ.m^-2，比基体增加了155％；并利用XRD、FTIR、DSC、SEM、毛细管流变仪等对该纳米复合材料进行表征。通过PCM复合材料冲击断面的SEM照片可以看到断面形貌丰富，表面起伏很大，应力断裂纹路较多，断口棱角模糊不清，说明韧性提高，而且观察不到明显的有机-无机相畴，表明MMT分散均匀，且分散个体尺寸基本达到纳米级。DSC表明，随MMT含量增加，PCM复合材料熔点及分解温度升高，改善了材料的耐热性，且结晶程度趋于完善，提高了材料拉伸性能；XRD表明，蒙脱土（MMT）的加入起到聚丙烯β晶型成核剂的作用。随MMT用量增多，β晶形比例增大，材料韧性得以提高；同时α晶型晶粒尺寸减小，增加了材料的强度；总的说来，蒙脱土在PP基体中纳米分散的片层作为第二相对材料起到了强韧化作用，而作为无机填料对结晶行为和结晶过程的影响同样与宏观机械性能的变化相吻合；流变测试表明，PCM具有切力变稀的特性，是假塑性流体，且随MMT含量的增加体系粘度较相同条件下的基体粘度有所下降，且对温度及切变速率的敏感度提高了，说明PCM的加工性能优于PP。更多还原

【Abstract】 Polypropylene is one of the popular plastics with preferable synthetical properties. Its defect of upper brittleness at low temperature restricts the further application of polypropylene. Lots of research on enhancing the touphness and intensity of polypropylene have been reported, such as mixing with elastomer and being filled in rigid inorganic particles,etc. These two methods of modifying polypropylene cannot increase the touphness and intensity simultaneously. In recent years, the hybrids based on polypropylene and inorganic clay minerals consisting of layered silicates have attracted great interest. The degree of modification was less than expectation value, however. A ’two-step’ method that mixed matrix with mother material, which prepared by the method of in-situ graft-intercalation, was introduced successfully in preparing polypropylene/montmorillonite nanocomposites (PCM) in this paper. The tensile strength of PCM achieved 42. 41 MPa and the maximum value of toughness strength was 10. 50kJ/m2. The structural charactristics and crystallization behavior of the composites were studied by means of XRD, FT-IR, DSC, SEM and capillarirheometer. The results indicated that the melting temperature and heat-resistant capability of modified PP were increased. Furthermore, the montmorillonite (MMT) possessed obvious nucleation effect on the crystallization process of ?-PP, thus with added qualities of MMT, the mechanic properties of PCM material were enhanced as while increasing content of P -PP and decreasing dimension of a crystal. Meanwhile, the viscosity of PCM composites which is pseudoplastical was less than PP matrix. Process performance of PCMincreased to some extent with increasing content of MMT.更多还原