玄武岩纤维布/不饱和聚酯复合材料耐老化性能

为探明玄武岩纤维/不饱和聚酯(UP,unsaturated polyester resin)复合材料的耐候性和力学性能,通过人工模拟加速气候箱对复合材料进行紫外光和冷凝处理,并测试、分析老化前后复合材料的力学性能、微观结构及化学结构的变化。力学性能测试发现,老化后的复合材料力学性能下降明显,拉伸强度、断裂伸长率、弯曲强度和弹性模量与未老化相比分别下降了35%、20%、60%和52%。扫描电子显微镜(SEM,scan electron microscope)观察老化前后的复合材料,发现包裹在纤维周围的树脂逐渐脱落,基体降解并产生碎片和横向裂纹并不断扩展形成多级开裂。傅立叶红外光谱分析(FTIR,Fourier transform infrared spectrum)测试发现,老化后的复合材料在1 725 cm-1处的酯羰基吸收峰减弱,1 280和1 130 cm-1处酯基消失;同时,在747和702 cm-1处的邻苯型1,2-二取代吸收峰也消失。研究结果表明,不饱和聚酯上的羰基与双键或苯环上的羰基共轭体系发生变化,使酯羰基分解产生CO;同时,聚酯发生链断裂、自由基终止等交联反应。玄武岩纤维/UP复合材料的耐老化研究有利于延长该产品的使用寿命,对下一阶段制备玄武岩纤维/亚麻纤维混杂复合材料的耐候性和力学性能提供参考依据。

Aging-resistant performance of basalt fabrics/unsaturated polyester resin composites

Abstract: Fiber-reinforced composites made up of unsaturated polyester resin (UP) matrices reinforced with glass, carbon and aramid fibers were commonly standard structural materials in engineering fields. In recent years, basalt fibers, have recently gained an increasing attention as possible replacement of the conventional glass or carbon fibers due to their advantages in terms of environmental-friendly, cost-effective, high chemical and physical properties. In order to verify the mechanical properties of basalt fiber fabrics/UP composites, the author used the artificial simulating climate box (UV and Condensation) to accelerate aging process of composites. The methods tested accurately the working life of composites and observed color change of fiber surface in different aging time (0, 3, 10, 13, 23 and 30 d). Variation of mechanical properties, microstructure, functional group were analyzed in detail by mechanic testing machine, scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR) respectively. The results showed that with the increase of aging time, the color of fiber surface became light yellow and the mechanical properties decreased gradually. Tensile strength and elongation at break of composites were slowly falling in 3 aging days, followed by significant decline after 10 days. Eventually, there were almost little change in the rest of aging time. Tensile strength and elongation at break of composites had decreased 35% and 20% compared with that of composites before aging time. A similar trend could be seen in flexural strength and modulus of elasticity of composites. However, they were more seriously than tensile strength and elongation at break and had decreased 60% and 52% compared with that of composites before aging time. The results of SEM indicated that resin wear around fiber, crack and fragment under the external force, due to degradation of matrix leading to interface failure between basalt fiber and UP. The author analyzed the mechanism of degradation and proposed the hypothesis that matrix had degraded and produced small molecule compound and radical after aging time. The FTIR results showed that Carbonyl and double bond or carbonyl conjugate system of UP were changed, and ester carbonyl was decomposed to release carbon dioxide. The peak at 1 725 cm-1 was the characteristic peak of C=O and absorption peak weakened. In addition, both C-O-C appearing at 1 280 and 1 130 cm-1 of ortho-phthalic-1, 2-disubstituted at 747 and 702 cm-1 disappeared. Meanwhile, cross-linking reaction such as molecule chains breakage and free-radical termination occurred in composites. This research method rapidly and accurately determined the working life and improved the aging resistance of basalt/flax fiber reinforced UP composites.