复合体系中微观相界面对材料性能的影响 Ⅰ.烷基羧酸盐对HDPE/CaCO_3复合体系的增韧效果

考察了烷基羧酸盐对高密度聚乙烯(HDPE)/CaCO_3复合体系中微观相界面的作用及其对复合体系增韧效果的影响。结果表明,烷基羧酸盐可以通过和CaCO_3的化学作用,被牢固地键接在CaCO_3表面上形成具有较高界面强度的第一相界面,当烷基羧酸盐的分子链长大于等于18个碳原子,并在1.0％～2.0％(质量分数,全文同)合适的添加量范围时,烷基羧酸盐可和基体进行有效的物理缠结形成具有较高界面强度的第二相界面;而只有在HDPE/CaCO_3复合体系中第一相界面、第二相界面均具有较高的界面强度,且在CaCO_3粒子之间的基体层厚度达到临界基体层厚度时,体系才能发生脆韧转变;分子链长为18个碳原子的烷基羧酸盐A3对HDPE/CaCO_3复合体系有着良好的偶联化效果,其体系不仅综合物性好,而且冲击韧性高,在本研究条件下当其处理量为1.5％、CaCO_3添加量为50％时,体系的缺口冲击强度可比基体提高5.2倍。

Effects of Micro - interfaces on Material Properties in the Composites I.Toughening Effects of Alkyl Carboxylic Salt on HDPE/CaCO_3 Composites

The effects of alkyl carboxylic salt on micro - interfaces and toughening of the HDPE/CaCO3 composite were studied in the present paper. The results indicated that the alkyl carboxylic salt was tightly bonded on the surfaces of CaCO3 by chemical reaction to form the first phase interface with relatively high strength. In the case of the alkyl carboxylic salt's molecular chain was longer than 18 C atoms and added dosage was in the range of 1.0% (w) -2.0% (w), the second phase interface with high strength formed between the alkyl carboxylic salt and the substrate through physical entangling. The "brittle - ductile transition" of the system took place provided that both the first and second phase interfaces possessed high strengths and the substrate thickness between the CaCO3 particles reached the critical value. The alkyl carboxylic salt (A3) with long chain served as coupling agent in HDPE/ CaCO3, and in fact, was superior to any other commercial coupling agents involved in this work. This system had not only excellent comprehensive properties but also high Izod impact toughness which was 5.2 times higher than the substrate under the condition of A3's content was 1.5% (w) and CaCO3 50% (w).