碳纤维表面化学结构对其增强环氧树脂基复合材料性能的分子动力学模拟

Molecular dynamics simulation of the properties of epoxy resin composite material reinforced by surface chemical structure of carbon fiber

采用分子动力学模拟手段,构建了碳纤维氧化表面及其增强的环氧树脂基复合材料模型。系统研究了碳纤维表面含氧官能团演变与碳纤维表面张力的作用关系,构建了碳纤维的不同氧化表面增强的环氧树脂模型,并进一步升温固化,获得最终的热固性复合材料。揭示了不同碳纤维表面化学结构对复合材料的剪切、拉伸及弯曲性能的影响。研究结果表明:—C=O和—COOH的含量提升有利于碳纤维表面能的提高,这主要归因于—C=O双键可弥补—C=C—破坏损失的表面共价键能,也提高了表面非键相互作用能。此外,一定含量含氧官能团的引入对复合材料力学性能均有不同程度的提高,但过量的含氧基团则削弱了力学性能。当电流密度为0.69 A/m^(2)时,对应碳纤维增强环氧树脂基复合材料的剪切应力、拉伸强度和弯曲强度均为最优,进一步提升的电流密度使得复合材料的力学强度均逐渐降低。

A molecular dynamics simulation method was used to construct the model of carbon fiber oxidation surface and its reinforced epoxy resin composite material.The relationship between the evolution of oxygen-containing functional groups on the surface of carbon fiber and the surface tension of carbon fiber was systematically studied.The epoxy resin model reinforced with different oxidation surfaces of carbon fiber was constructed,and the final thermosetting composite material was obtained by further heating and curing.The effects of different surface chemical structures of carbon fiber on the shear,tensile and bending properties of composite material were revealed.The research results showed that the increase in the content of-C-O and-COOH was beneficial for the improvement of the surface energy of carbon fiber,which was mainly attributed to the fact that-C=O double bonds could compensate for the loss of surface covalent bond energy caused by-C=C—damage,and also increased the surface non-bonding interaction energy.In addition,the introduction of a certain amount of oxygen-containing functional groups improved the mechanical properties of composite material to varying degrees,but excessive oxygen-containing functional groups weakened the mechanical properties.When the current density was 0.69 A/m^(2),the corresponding shear stress,tensile strength and bending strength of carbon fiber reinforced epoxy resin composite material were all optimal.The further increase in current density gradually reduced the mechanical strength of composite material.