类玻璃环氧高分子/碳纳米管复合材料的界面调控及高性能化研究

Study on the Interface Control and High Performances of Epoxy Vitrimer/Carbon Nanotube Composites

在环氧类玻璃高分子中引入大量的动态共价键会导致其力学性能显著降低,因此本文采用聚离子液体原位聚合修饰碳纳米管(PIL-MWCNT)改性环氧类玻璃高分子,发现其拉伸强度、断裂伸长率、冲击韧性和断裂韧性分别提高79.5%、1851.6%、158.3%和404.4%。这是由于聚离子液体(PIL)吸附在碳管表面促进碳管分散,增强碳管和基体相互作用。并且,PIL-MWCNT改性后临界应力强度因子(K_(Ic))值较未改性体系提高了158.3%,应力松弛时间降低至16.7%。PIL-MWCNT强界面结合力引起基体塑性形变以及MWCNT的裂纹偏转、裂纹钝化和裂纹桥接,实现了环氧类玻璃高分子的增韧。此外,PIL-MWCNT体系重塑后力学性能保持在80%以上(MWCNT体系为70%以上),起始热分解温度升高了6.2℃,残炭量降低了14.1%。本章提供了一种简单高效的纳米粒子分散方法,进而显著提高环氧类玻璃高分子的力学性能以及热机械性能。

The mechanical properties of epoxy vitrimers are reduced due to the introduction of abundant dynamic covalent bonds.In this study,the properties of epoxy vitrimers were modified by the multiwalled carbon nanotubes(PIL-MWCNTs)that were modified by the in-situ polymerization of poly(ionic liquid)(PIL).The results show that the tensile strength,elongation at break,impact toughness,and fracture toughness are respectively increased by 79.5%,1851.6%,158.3%and 404.4%.This is due to the adsorption of PIL on the surface of carbon tubes,which promotes the carbon tube dispersion and enhances the interactions between the carbon tubes and the matrix.In addition,compared with the unmodified system,the K_(Ic)of epoxy vitrimers modified by PIL-MWCNTs is increased by 158.3%and the stress relaxation time is decreased by 16.7%.The strong interfacial bonding force of PIL-MWCNTs causes the plastic deformation of the matrix and the crack deflection,crack blunting and crack bridging of MWCNTs,which toughens the epoxy vitrimers.In addition,the mechanical properties of PIL-MWCNTs system remain above 80%after remodeling(above 70%for the MWCNTs system),the initial thermal decomposition temperature is increased by 6.2℃,and the carbon residue is decreased by 14.1%.This paper provides a simple and efficient nanoparticle dispersion method to significantly improve the mechanical and thermo-mechanical properties of epoxy vitrimers.