填充增韧聚丙烯复合材料的断裂韧性及增韧机理

用表面处理的ＣａＣＯ３填充聚丙烯（均聚物ＰＰ），ＰＰ／ＣａＣＯ３复合材料的杨氏模量和缺口冲击强度同时得到增加，克服了通常填料填充聚合物降低韧性的缺点．用Ｊ积分研究其断裂韧性给出：裂纹扩展阻力ｄＪ／ｄ（△ａ）低是聚丙烯缺口脆性的主要原因，随着填料体积分数Ｖｆ的增加ＰＰ／ＣａＣＯ３的Ｊｃ出现一极大值，但其裂纹扩展阻力却不断增大；用裂纹引发点后的Ｊｃ＝Ｊｃ＋［ｄＪ／ｄ（△ａ）］·△ａ＝Ｊｅ（Ｊ积分弹性分量）＋Ｊｐ（Ｊ积分塑性分量）可全面表征韧性聚合物材料的断裂韧性；ＰＰ／ＣａＣＯ３的Ｊｐ明显增加，是裂纹扩展阻力和Ｊｔ增加的原因．ＳＥＭ分析结出，ＣａＣＯ３填料在裂尖损伤区内引起强烈的空洞化损伤，并增强了裂尖钝化破坏过程，这些细观损伤机制的变化，导致能量耗散增加，可用滞后分量Ｊｈ定量表征．由此给出聚合物材料被增韧的Ｊ积分判据为：复合材料的Ｊｈ＞基体的Ｊｈｍ．

THE FRACTURE TOUGHNESS AND TOUGHENING MECHANISM OF TOUGHENED POLYPROPYLENE/CaCO, COMPOSITES

oughened PP /CaCO3 composites were obtained by designed interface of composite1]. Resistance curve method has been used to detendne the Jc values of polypropylene (PP) and the toughened polypropylene /CaCO3 composites. The addition o f CaCO3 gives rise to substantial increases in both the Young’s modulus (E) and notched Izod impact strength (SI), a slight increases in Jc and a sharp rise in the crack propagation resistance dJ/ d(△a). The results show that the incorporation of filler leads to both stiffening and toughening effects for pp, the elastic component Jeof the J is larger than the plastic component Jp (=hysteresis component Jn). As the filler content increases, Jc changes slightly but Jh rises sharply, indicating large dissipation of energy. Scanning electron microscope (SEM) observation reveals that the microscopic damage process responsible for energy dissipation are cavitation and plastic deformation. It is proposed that the criterion for toughening in a particulate-filled polymer is that the composite has a higher Jh value than the polymer.