尼龙／乙烯—醋酸乙烯酯共聚物接枝马来酸酐共混体系的研究

通过双螺杆挤出机利用熔融挤出法制备了增韧的尼龙66／乙烯－醋酸乙烯酯共聚物接枝马来酸酐共混物（PA66／EV－g-MAH）。实验结果表明，未经接枝改性的EVA与PA66是不相容的，对增韧PA66几乎没有贡献，而EVA－g-MAH则出现了明显的增韧效果。在熔融挤出过程中，PA66与EVA－g-MAH发生了原位化学反应，生成了PA66－EVA共聚物，这种共聚物细化了分散相尺寸，使得分散相在PA66基体中分散得更均匀，提高了两相的相容性，同时增强了丙相界面间的结合力，便利应力能够在两相产有效地传递，这种界面形态的改善直接影响到共混物力学性能的变化。随着EVA－g-MAH含量的增加，PA66/EVA-g-MAH共混物的冲击强度提高，当PA66／EVA－g-MAH的共混比为70／30（质量比）进，体系发生了脆韧转变，冲击强度达到了最大，比纯PA66、PA66／EVA（70／30）共混物提高了12倍。和PE－g-MAH、PP-g-MAH相比，EVA-g-MAH对PA66的增韧效果最好。

Study on PA66/EVA Copolymer Grafted Maleic Anhydride Blends

Super-tough polyamide 66(PA66) was prepared by using ethylene vinyl acetate copolymer (EVA) grafted with maleic anhydride(EVA-g-MAH) as a compatibilizer in a twin-screw extruder.The experimental results showed that the unmodified EVA was uncompatible with PA66 and had hardly any contribution to the toughness of PA66,whereas the EVA-g-MAH had an obvious compatibilizing and toughening effect on PA66.During the melt extrusion process,the in-site reaction between PA66 and EVA-g-MAH was performed and the in-site PA66-g-EVA graft copolymer was formed,which acted as an interfacial agent between the elastomer disperse phase and the PA66 matrix.The in-site PA66-g-EVA graft copolymer improved the dispersion and interfacial morphology. The improvement of morphology directly affected mechanical properties of PA66/EVA-g-MAH blends. A transition from brittle to ductile occurred in the PA66/EVA-g-MAH blend with composition ratio of 70:30(mass ratio) and the maximum impact strength was obtained,which was about twelve times higher than that of PA66/EVA blend.Compared with PE-g-MAH and PP-g-MAH,the toughening effect of EVA-g-MAH was the best.