硅溶胶改性处理对碳纤维/环氧树脂复合材料拉伸性能的影响

Effect of Silica Sol Modification on the Tensile Property of Carbon Fiber/Epoxy Composites

用溶胶-凝胶法制备硅溶胶对碳纤维进行表面改性,观测了环氧树脂液滴在单向排列碳纤维集束表面的铺展过程;以环氧树脂为基体制备单向排列的碳纤维/环氧树脂复合材料,研究了硅溶胶改性处理碳纤维对其拉伸性能的影响。结果表明:碳纤维经过硅溶胶改性处理后,Si—o—Si,-NH_2等极性官能团的引入改善了环氧树脂对其的浸润性能,从而改善了碳纤维与环氧树脂间的界面粘结性能,使碳纤维/环氧树脂复合材料的横向拉伸强度显著改善,但纵向拉伸强度影响不大;与未经过表面处理的复合材料相比,经过硅溶胶改性处理的碳纤维/环氧树脂复合材料其横向拉伸强度提高了62.74%;与用硝酸处理的碳纤维制备的复合材料相比,用硝酸处理后再用硅溶胶处理的碳纤维所制备的复合材料,其横向拉伸强度提高了35.27%。

Silica sol was prepared by sol-gel method to modify the surface of carbon fiber; the process of spreading for epoxy droplet on parallel carbon fiber sheet was observed; the unidirectional carbon fiber reinforced epoxy resin matrix composites were prepared, and the effect of silica sol modification of carbon fiber on the tensile property of the composites was investigated. The results showed that the wettability of epoxy to the silica sol modified carbon fiber has been improved greatly due to the introduction of polar functional groups such as Si--O--Si and --NH2. The coating of silica sol improved the adhesion between carbon fiber and epoxy, resulting in an increasement of 62.74% of the lateral tensile strength, comparing with that of the unmodified carbon fiber reinforced composites, but little change of the longitudinal tensile strength. Likewise, the lateral tensile strength of composites from carbon fiber pretreated by nitric acid and subsequently modified by silica sol was increased by 35.27%, comparing with composites from pure nitric acid treated carbon fiber.