PP/L-CaCO_3复合材料的拉伸断裂韧性

TENSILE FRACTURE TOUGHNESS OF POLYPROPYLENE/ LIGHT CALCIUM CARBONATE COMPOSITES

研究了一种在轻质碳酸钙（Ｌ－ＣａＣＯ３）填料存在下可生成较大量β－晶的聚丙烯（ＰＰ）与Ｌ－Ｃａ－ＣＯ３热熔复合而得的复合材料的拉伸断裂行为。发现在Ｌ－ＣａＣＯ３含量为２０％～２５％时，复合材料具有较好的断裂韧性和比母体ＰＰ大得多的断裂伸长率（ε）。当Ｌ－ＣａＣＯ３先用二核铝酸酯处理再与上述ＰＰ复合，所得的复合材料在Ｌ－ＣａＣＯ３含量为１０％～２５％时的断裂韧性和ε又有显著增加。复合材料的ε随Ｌ－ＣａＣＯ３含量而变化的规律基本上与ＰＰβ－晶含量随Ｌ－ＣａＣＯ３含量而变化的规律一致。扫描电镜观察表明，ε较大的复合材料在拉伸过程中形成丝状结构。分析认为复合材料的ε的增加主要是在拉伸过程中在Ｌ－ＣａＣＯ３粒子平行于拉伸方向的两极首先发生脱粘空化，并引起在Ｌ－ＣａＣＯ３粒子表面和周围树脂基体的ＰＰβ－晶发生塑性形变的结果。

In composites, the PP can form a considerable amount of β crystals in the presence of L CaCO 3. It was found that the composites containing 20%～25 mass% of L CaCO 3 possesed better fracture toughness and higher elongation ratio at break ( ε ) than the PP itself. When L CaCO 3 was treated with dimeric aluminates and then blended with the PP mentioned above, the fracture toughness and ε farther increased for the resultant composites with 10%～25 mass% of L CaCO 3. The change of ε with the content of L CaCO 3 in the composites is basically in agreement with that of PP β crystal amount with the content of L CaCO 3. Observations by SEM showed that fibrilform structures formed during the process of tensile testing for the composites with higher ε . It is considered that the increase in ε for the composites is the result of disadhesion and void formation on the poles of L CaCO 3 particles parallel to the direction of tension, and the plastic deformation of PP β crystals on the surfaces of L CaCO 3 particles and around them.