HNO_3/H_2SO_4处理对碳纤维表面性质以及碳纤维/环氧树脂复合材料力学性能的影响

Effect of H_2SO_4/HNO_3 treatment on surface qualities of carbon fibers and mechanical properties of carbon fiber/epoxy composites

采用浓HNO3/浓H2SO4混合酸在60℃超声环境下对T300碳纤维进行表面氧化处理,并以其为增强体制备碳纤维/环氧树脂复合材料。利用X射线光电子能谱仪、拉曼光谱仪、扫描电镜、原子力显微镜对表面氧化前后的碳纤维形态与表面化学性质进行表征,研究氧化时间对纤维的表面形貌与表面性质以及碳纤维/环氧树脂基复合材料力学性能的影响。结果表明,氧化初期,碳纤维表面生成S—、N—含氧基团,以及—OH和—C=O;后期形成—COOH,氧化时间为15 min时,—COOH的浓度达到最大值。碳纤维/环氧树脂复合材料的强度随混合酸氧化时间延长而不断增强,氧化15 min时强度达到峰值,相比于未氧化处理的样品,复合材料层剪切强度从16.3 MPa提高到38.8 MPa,抗弯强度从148.3 MPa提高到379.7 MPa。

T300 carbon fiber was oxidized in H2SO4/HNO3 liquid at 60℃ under ultrasound environment. The oxidized T300 fiber was used to prepare the carbon fiber reinforced epoxy resin composite. The morphology, surface chemistry qualities of carbon fiber and mechanical properties of the composite were characterized by means of X-ray photoelectron spectroscopy, Raman spectroscopy, scanning electron microscopy, atomic force microscopy. The results show that, oxygen-containing S— and N— group,—OH, and—C=O generate during the early stage of oxidation,—COOH generates during the late stage of oxidation. The concentration of—COOH reaches the maximum value after 15 min oxidation. The strength of composite increases with increasing oxidation time, and reaches the peak value at 15min. Compared with non-oxidation sample, the interlaminar shear strength （ILSS） of oxidation treated composite increases from 16.3 MPa to 38.8 MPa and the bending strength of the composite increases from 148.3 MPa 379.7 MPa.