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本文用应力松弛方法研究了短切玻璃纤维增强聚丙烯复合材料的粘弹性行为。用时-温等效原理求出了不同玻璃纤维含量和含有不同偶联剂试样的应力松弛总曲线、表观活化能、最大松弛时间和松弛谱。实验证明,这些参数对复合材料的增强和改性效果的反应是敏感的。 考察了WLF方程的适应范围,证明对不含偶联剂的试样,玻璃纤维含量为5—35％(重量百分数),温度为20—120℃范围内;以及玻璃纤维含量为20％的含偶联剂A和B(单独使用或混合使用)试样,在温度约为20～100℃范围内符合WLF方程。这表明我们有可能应用时-温等效原理,从不同温度下短时间的应力松弛实验结果来予测复合材料的长期力学性能。 从实验结果可以推测,偶联剂A和B对纯树脂起增韧作用,并在玻璃纤维和聚丙烯树脂间起偶联作用。对影响复合材料长期力学性能的一些因素作了初步的分析。
In this paper, the viscoelastic behavior of chopped glass fiber reinforced polypropylene composites was studied by stress relaxation method. The total stress relaxation curve, apparent activation energy, maximum relaxation time and relaxation spectrum of different glass fiber content and different coupling agent samples were obtained by the time-temperature equivalence principle. Experiments show that these parameters are sensitive to the enhancement of the composite and the reaction of the modification. The WLF equation was investigated for its suitability for samples containing no coupling agent and having a glass fiber content of 5 to 35% by weight and a temperature in the range of 20 to 120 ° C; and a glass fiber content of 20% The coupling agents A and B (used alone or in combination) sample conform to the WLF equation at a temperature in the range of about 20-100 ° C. This shows that it is possible to predict the long-term mechanical properties of composites based on the time-temperature equivalence principle from the results of stress relaxation tests at different temperatures for a short period of time. It can be inferred from the experimental results that the coupling agents A and B have a toughening effect on the pure resin and a coupling action between the glass fiber and the polypropylene resin. Some factors affecting the long-term mechanical properties of composites were analyzed.