【作者】 徐立新；

【导师】 钟明强；

【作者基本信息】 浙江工业大学 ， 材料学， 2002， 硕士

【摘要】 本文分别研究了PP／POE，PP／纳米CaCO₃和PP／POE／纳米CaCO₃三类复合体系。在研究纳米改性和传统的弹性体改性规律的基础上，重点探讨了两类改性方法之间的联系与协同作用机理。 通过PP／纳米CaCO₃二元体系的研究发现，经表面处理的纳米CaCO₃对PP具有同时增强增韧作用，其改性效果主要取决于其表面处理情况，同时与其粒径大小及分布、基体树脂的颗粒形态及两相的复合工艺等因素有关。在合适的工艺条件下，采用经表面处理过的纳米CaCO₃在用量为6-8Phr时二元体系的综合力学性能最佳，同时具有较好的加工流变性能。相比纯PP体系，其拉伸强度约提高15-20％，冲击强度约提高40-50％。 通过偏光显微镜观察及DSC分析发现，纳米CaCO₃在PP熔融冷却过程中能起到明显的结晶诱导作用，使PP得以在较高的温度下结晶且使球晶尺寸变得细小而均匀。经过合适的表面处理后，或是在允许的范围内提高用量，纳米CaCO₃对体系的这种结晶诱导作用将变得更加明显。这正是纳米CaCO₃能对PP增强增韧的一个内在原因。 在PP／弹性体二元体系的研究中，主要比较了三种不同的弹性体：POE8180、POE8200和EPDM。发现POE8200对PP具有较好的增韧作用，而且能赋予体系理想的加工流变性能，随其用量的增加，体系的冲击强度明显上升，但体系的拉伸强度却急剧下降，当其用量达12Phr时，体系的冲击强度相比纯PP约提高2.8倍，拉伸强度则下降25％。可见，利用传统的弹性体改性很难使PP获得良好的综合力学性能。 在PP／POE／纳米CaCO₃三元体系中，纳米CaCO₃主要起增强作用，保持POE添加比例不变，随纳米CaCO₃含量的增加，体系的拉伸强度先上升后下降；POE则赋予体系良好的韧性，保持CaCO₃含量不变，体系的冲击强度随POE添加比例的增加而明显上升。纳米CaCO₃的存在，在一定程度上能减缓因POE的加入而引起体系拉伸强度下降的幅度，进而使体系获得良好的综合力学性能。此外，通过不同的三元混合顺序的比较，发现纳米CaCO₃在PP和POE两相间的不同分配比例对体系的力学改性效果也有一定的影响。结果表明：捉高CaCO₃在体系中分散的均匀性，同时增加其在PP连续相中的分散浓度，对体系的增强增韧比较有利。 总之，采取两类改性方法相结合，当POE为12 Phr、纳米CaCO。为6七 Phr时体系具有较好的综合力学性能，其冲击强度相比纯PP约提高1．85倍，而拉伸强度仅下降15％左右。更多还原

【Abstract】 In this paper , PP/POE, PP/nano-CaCO3 and PP/POE/nano-CaCO3 composites are studied systematically. On the basis of study on the regulation of elastomer and nano-CaCOa on PP, we put great emphasis on the discussion of the relation between two kinds of modification procedures.The mechanical properties of PP/nano-CaCOs composite show that PP can be reinforced and toughened simultaneously by nano-CaCOs treated in proper way. The effect of nano-CaCOs on PP is chiefly decided by the circumstance of surface pre-treatment of nano-CaCOs , the particle diameter and distribution of nano-CaCOs , the appearance of PP particles and the processing parameters of PP/nano-CaCOs composites as well. With the addition of 6-8 phr. Surface-treated nano-CaCOj, the composite shows the best mechanical properties and the better processing properties,the Izod impact strength increases about 40-50% compare with pure PP, and the tensile strength increases about 15-20%. The TEM morphology show that the dispersant has better dispering effect on nano-CaCOs in PP.Crystal structure and characteristics of PP/nano-CaCOs composite are observed and studied by polarizing microscope and DSC respectively. Results show that nano-CaCOs acts as a nucleation agent in PP, thus upgrading the crystal temperature and nucleation rate. The spherulites of the crystal become small and even,but basically there is little effect on crystalline degree and melt point. Within the scope of admission, increasing the content or surface-treatment of nano-CaCOs have obvious influence on crystal structure characteristics of the system.The polyolefin elastomer POE and EPDM are used as the impact modifier for PP in the second part of the project. The processability,crystallizing behavior and mechanical properties of PP/POE and PP/EPDM blends are analyzed comparatively by Torque Rheometer,Differential Scanning Calorimetry(DSC) and mechanical test respectively.The results show that POE8200 is better than EPDM on processability and toughening effect. With the addition of 12 phr. POE8200, the Izod impact strength of PP/POE composite increases about 2.8 times compare with pure PP, but the tensilestrength descends about 25%.The reinforcing and toughening effects of PP/POE/CaCOs composite is also studied. By addition of POE ,the Izod impact strength of the system is improved dramatically,while the tensile strength is reduced,however, nano-CaCOs can slow down the descent of the tensile strength on a certain degree. As the blend ratio of PP/POE/nano-CaCOs composite is 100/12/8, the two particles have the best comprehensive mechanical modification effect, the Izod impact strength increases about 1.85 times compare with pure PP, and the tensile strength descends only about 15%.In PP/POE/CaCOs system, when the nano-CaCOs is distributed in different proportion between PP and POE, the system will show different mechanical properties. The result shows that it is beneficial to reinforcing and toughening of the system to improve the dispering effect and increase the concentration of nano-CaCOs in PP continuous phase.更多还原