苎麻纤维增强酚醛树脂基复合材料的湿热性能研究

Hygrothermal Properties of Ramie Fiber/Phenolic Resin Composite under Different Hygrothermal Conditions

通过模压工艺制备了苎麻纤维织物增强酚醛树脂基复合材料层合板,研究了模压层合板在不同湿热环境下的水吸收与扩散及力学性能。研究表明:在20℃,40℃和60℃三种温度下,相对湿度的上升使层合板瞬时吸湿速率增大很明显,而在50%相对湿度下,温度对层合板的饱和吸水率的影响不大。当吸湿份数在0.5以下时,层合板在50%的相对湿度和20℃,40℃和60℃三种温度下,水扩散系数分别为2.16×10-6cm2/s,2.94×10-6cm2/s和6.61×10-6cm2/s。层合板的力学性能随吸水率的增加而下降。通过扫描电子显微镜(SEM)观察,层合板力学性能下降的主要原因是水分破坏了纤维和树脂的界面,同时进入纤维的空隙中,影响了复合材料中的应力传递,使复合材料力学性能下降。

Ramie fiber fabric reinforced phenolic resin composite laminates were prepared, and the moisture absorption, diffusion properties and mechanical properties were studied under different hygrothermal conditions. Results show that instantaneous moisture absorption rate of the laminate increases with the increase of relative humidity at 20℃ ,40℃ and 60℃, and that the temperature has unobvious effect on the hygrothermal properties of the laminate under 50% relative humidity. When the moisture absorption fraction is less than 0.5, the moisture diffusion coefficient of the laminate are 2.16 × 10^-6cm^2/s, 2.94 ×10^-6cm^2/s and 6.61 × 10^-6 cm^2/s respectively under the temperatures of 20℃ ,40℃ and 60℃ , and the relative humidity of 50%. The mechanical properties of the laminates decrease with the increase of the moisture absorption rate. The SEM photographs indicate that the moisture absorption damages the interface adhesion between fiber and resin of the composite, resulting in weak stress transferring between the fiber and the resin matrix.