Novel approach for silane treatment of flax fiber to improve the interfacial adhesion in flax/bio epoxy composites

Natural fibers have been approved as an excellent alternative for traditional reinforcements in polymer composites. However, the main disadvantage of natural fibers as reinforcements is their poor interaction with polymeric matrices due to their hydrophilic nature. In order to improve their compatibility as composite reinforcement, surface treatments are required. Silane treatment has been widely used to modify hygroscopic properties of natural fibers. In this study, a new method of silane treatment has been developed without the prehydrolysis and curing/dehydration of silanol groups. To do so, flax fibers were modified through 2,2,6,6-tetramethylpiperidine-1-oxy radical (TEMPO)-mediated oxidation followed by direct application of the amino-silane. The fiber/matrix interfacial adhesion was examined by measuring interlaminar shear strength. Thermogravimetric analysis and dynamic mechanical analysis were performed to study the thermal resistance and thermomechanical properties of the composites. The results revealed that fiber/matrix adhesion was improved in the oxidized silanized fiber composite. In addition, water absorption was significantly reduced (20%) in the oxidized silanized fiber reinforced composite compared with the as-received one.

天然纤维已被认可为聚合物复合材料中传统增强材料的一种极佳替代品。然而，天然纤维作为增强材料的主要缺点是，由于其亲水性，它们与聚合物基体的相互作用较差。为了提高它们作为复合材料增强材料的相容性，需要进行表面处理。硅烷处理已被广泛用于改变天然纤维的吸湿性能。在这项研究中，开发了一种新的硅烷处理方法，无需对硅醇基团进行预水解和固化/脱水。为此，亚麻纤维先通过2,2,6,6 - 四甲基哌啶 - 1 - 氧基自由基（TEMPO）介导的氧化进行改性，然后直接施加氨基硅烷。通过测量层间剪切强度来检测纤维/基体的界面粘结性。进行了热重分析和动态力学分析，以研究复合材料的耐热性和热机械性能。结果表明，氧化硅烷化纤维复合材料中的纤维/基体粘结性得到了改善。此外，与原始材料相比，氧化硅烷化纤维增强复合材料的吸水率显著降低（20%）。