化学处理和吸湿水对剑麻纤维及其与树脂界面性能的影响

使用KMnO₄、NaOH、阻燃剂、硅烷对剑麻纤维进行表面处理。采用单丝拉伸和微脱粘方法分别测试了剑麻纤维的拉伸性能及其与改性丙烯酸酯、环氧树脂的界面性能,考察了吸湿水对剑麻纤维表面形貌、拉伸性能及其与树脂界面粘结的影响,分析了相应的破坏模式。结果表明,经过表面化学处理后剑麻纤维的拉伸强度和模量均有不同程度的下降,其中经KMnO₄和硅烷处理后,纤维拉伸强度下降了44%,经NaOH处理后其拉伸强度降低了27%,阻燃剂处理对剑麻性能的影响不明显。表面化学处理还会降低剑麻纤维与改性丙烯酸酯的界面粘结强度,其下降的幅度与纤维拉伸强度下降程度不一致,阻燃剂处理的剑麻/改性丙烯酸酯的界面强度最低,仅为2.0 MPa,较未处理剑麻纤维复合体系下降了80%。经硅烷处理后,剑麻纤维的吸水率下降,吸水后其拉伸性能保留率高于未处理剑麻纤维。湿态条件下未处理剑麻纤维与环氧树脂的界面强度为6.6 MPa,高于硅烷处理剑麻/环氧树脂的界面强度,其断口形貌表明硅烷处理可导致微纤之间的弱粘结,从而降低了剑麻纤维自身及其与树脂的界面性能。

Effect of chemical treatment and water absorption on properties of sisal fiber and its interface with resin

Sisal fibers with surface treatments, including potassium permanganate, sodium hydroxide, flame retardant agent, silane, and without treatment were investigated. The tensile properties and interfacial shear strength (IFSS) of sisal fiber with modified acrylate and epoxy resin were tested by using single fiber tensile method and micro-droplet debonding method, respectively. The effect of water absorption on the sisal fiber surface morphologies, the tensile properties and its interfacial adhesion were analyzed, and the corresponding fracture mode as well. The results show that after chemical treatments the tensile strength and modulus of sisal fibers are decreased to varying degrees. Compared with the untreated sisal fiber, the tensile strengths of potassium permanganate and silane treated fibers both decrease by 44%, the strength of sodium hydroxide treated fiber decreases by 27%, while that of flame retardant treated fiber is almost equivalent. The chemical treatments can decrease the IFSS of sisal fiber/modified acrylate and the decreasing degrees are different from those of the fiber tensile properties, in which lowest IFSS is found for flame retardant sisal fiber/modified acrylate with 2.0 MPa, decreasing by 80% in comparison with the untreated fiber system. After silane treatment, the water absorption rate is decreased, and the property retention rate is higher for the sisal fiber than those of the untreated fiber. For the hygrometric state sisal fiber/epoxy, the untreated fiber system shows IFSS of 6.6 MPa, higher than the silane treated fiber system. The fracture morphologies indicate that silane treatment tends to reduce the bonding of the inter-fibrils, thereby decreasing the sisal fiber tensile and interfacial properties with resin.