聚多巴胺改性竹长纤维对环氧树脂基复合材料性能的影响

Effect of Bamboo Fiber Modified with Polydopamine on the Properties of Epoxy Resin Based Composites

为改善竹长纤维与环氧树脂(EP)的界面相容性,开发高性能竹塑复合材料,采用多巴胺(DA)自聚形成聚多巴胺(PDA)改性竹长纤维,热压法制备竹纤维/EP基复合材料。通过万能力学试验机、表面张力测量仪等设备探究PDA的合成条件对EP基复合材料力学性能、润湿性等性能的影响机制。结果表明,采用三羟甲基氨基甲烷调节pH为8.5,质量浓度为2.0 g/L的聚多巴胺改性竹纤维,改性竹纤维及复合材料表面接触角增大,表面能下降,极性降低。FTIR和XPS表明改性竹纤维表面N元素含量增加,多巴胺分子结构中的儿茶酚基团与竹纤维中游离的羟基结合形成氢键,复合材料吸水性能下降。XRD显示改性竹纤维结晶度提高。复合材料的弯曲强度、弯曲模量、冲击强度分别增强至131.10 MPa、8097.61 MPa、25.68 kJ/m^(2),比未改性复合材料分别提高5.36%、18.8%、36.02%。DMA和TG测试显示,改性复合材料的储能模量、损耗模量和热稳定性增强。

In order to enhance the interface compatibility between bamboo fiber and epoxy resin(EP),a high-performance bamboo fiber was developed.Polydopamine(PDA)modified bamboo fiber was formed by dopamine(DA)autopolymerization,and bamboo fiber/EP composite was prepared by hot pressing.The effects of synthetic conditions of PDA on the mechanical properties and wettability of EP-based composites were investigated by means of universal mechanical testing machine and surface tension measuring instrument.The results demonstrated that polydopamine-modified bamboo fiber with a pH value of 8.5 and a concentration of 2.0 g/L could increase the surface contact angle,reduce surface energy,as well as decrease polarity in both modified bamboo fiber composite material.FTIR and XPS analyses revealed an increased nitrogen content on the surface of modified bamboo fiber due to hydrogen bonding formed between catechol groups in dopamines molecular structure and free hydroxyl groups in bamboo fibers,resulting in reduced water absorption by the composite material.XRD analysis indicated improved crystallinity in modified bamboo fibers.The bending strength,bending modulus,and impact strength were enhanced to 131.10 MPa,8097.61 MPa,and 25.68 kJ/m^(2),respectively for the composite material after modification;these values were found to be higher than those observed for unmodified composites by 5.36%,18.8%,and 36%,respectively.DMA and TG tests showed that the energy storage modulus,loss modulus and thermal stability of the modified composite were enhanced.