左旋多巴胺处理对芳纶表面结构与性能的影响

利用L-3,4-二羟基苯丙氨酸(L-DOPA)的氧化自聚合,在杂环芳纶表面修饰聚L-3,4-二羟基苯丙氨酸(PDOPA)活性涂层来提高芳纶的表面活性及耐紫外辐照性能。结果表明:改性后芳纶表面粗糙度显著提高,同时,PDOPA涂层上大量的羧基、羟基等活性单元均有利于增强与环氧树脂的机械锁合力,改性后芳纶/环氧树脂复合材料的界面剪切强度提高了32.0%。此外,上述改性过程对杂环芳纶本身力学性能影响较小,纤维的拉伸强度保持率可以达到100%,基本实现了无损改性。同时,由于PDOPA的保护作用,改性后芳纶的耐紫外辐射性能显著提高;经过168 h紫外线辐照处理后,其拉伸强度保持率可达到92.5%,显著提升了杂环芳纶的耐紫外线辐照特性。

Effects of L-3,4-Dihydroxyphenylalanine on Surface Microstructure and Properties of Aramid Fibers

The surface of the heterocyclic aramid fibers was coated with L-3,4-dihydroxyphenylalanine(LDOPA),which could be oxidized and self-polymerized to poly L-3,4-dihydroxyphenylalanine(PDOPA)to improve the surface activity and UV-resistance of aramid fibers.The microstructure,chemical properties of modified fibers and interfacial properties to the epoxy resin were investigated by scanning electron microscopy,X-ray photoelectron spectroscopy and microsphere debonding experiments.As a result,the surface roughness of the modified aramid fibers is significantly improved and achieved a strong mechanical interlock with the polymer matrix.The interfacial shear strength of modified aramid fibers/epoxy composites increases by 32.0%and the tensile strength retention rate of the modified aramid can reach 100%.The above modification process has little effect on the thermal stability and mechanical properties of aramid fibers,indicating it is a non-destructive modification method.Under the protection of PDOPA,the modified fibers possess excellent UV radiation resistance.The tensile strength retention rate of modified fibers reaches92.5%after 168 h of UV irradiation.