基于无苯乙烯不饱和聚酯的大麻纤维增强复合材料的制备及其机理

In this proposal, we aim at developing styrene-free unsaturated polyester (UPE) resin and providing solution for the problem of styrene emission during the manufacture of glass-fiber reinforced UPE composites. Also, hemp fibers were adopted as the reinforcement to replace glass fibers and to prepare hemp-fibers/UPE composites due to that styrene and certain inhalable glass fibers had been listed as two of the anticipated human carcinogens in the 12th Report on Carcinogens by the National Toxicology Program, US Department of Health and Human Services. Therefore, two novel reactive dilutes from the reaction products of acryloyl chloride or undecylenic acid (UA) with glycerol will be synthesized for the production of styrene-free UPE resins. And styrene-free UPE resins with novel reactive dilutes will be prepared and characterized. Thus the mechanism of reaction between the novel dilutes and UPE during the curing of UPE resins will be revealed. Hemp fiber reinforced UPE composites based on the new styrene-free UPE resins will be prpepared and evaluated, and compared with those based on the commercially available and conventional UPE resin in terms of mechanical properties and water resistance. Surface modification of hemp fibers with novel compatibilizers will be conducted to improve the interfacial adhesion between fibers and UPE resins. The comprehesive characterization of composite interface adhesion will be developed and the mechanism of the chemical bonds formation among fibers, compatibilizers and UPE resins will be investigated. The proposed novel styrene-free UPE resins whose reactive dilutes can be obtained from UA and glycerol which are based on renewable materials and are expected to be much more environmentally friendly than the present UPE/styrene resin system, and are not expensive. More importantly, UPE resin has a huge market. If styrene would be replaced by the novel reactive dilutes, the hazardous air pollutants released from composites plants could be significantly reduced. The successful completion of this project will provide cost-competitive, environmentally friendly, commercially available, renewable-material-based resins which have great potential application in the manufacture of wind turbine blade and inner parts of automobiles. The research enables us to gain a good understanding of the mechanisms for these new resins, which will be good contributions to composite material science.

针对纤维增强不饱和聚酯复合材料制备中产生的苯乙烯释放危害人体健康问题，以生物柴油制备过程的副产物甘油和有机不饱和脂肪酸等为原料，合成二种生物质基反应性溶剂，以此代替苯乙烯作为不饱和聚酯树脂的反应性溶剂与交联剂，揭示反应性溶剂与不饱和聚酯树脂在固化过程中的反应过程。采用高强度大麻纤维代替玻璃纤维，制备大麻纤维增强无苯乙烯不饱和聚酯复合材料；对大麻纤维进行表面改性，把具有高度不饱和双键的共聚物引入到树脂体系中，从而改善纤维与树脂基体之间相容性。通过复合材料界面特性分析与表征，阐明纤维表面改性在材料复合过程中的作用以及纤维/树脂基体间化学键形成的条件及机理，为环境友好、低成本、高强度大麻纤维增强不饱和聚酯复合材料的制备与应用提供科学依据。这种以可再生原料制备的生物质新材料，有望作为玻璃纤维增强石油基树脂复合材料的替代品，用于制造风电叶片、汽车内零部件等。

苯乙烯是不饱和聚酯树脂(UPE)体系中最常用的反应型溶剂与交联剂。在UPE树脂固化过程中，苯乙烯不仅起到“桥联”作用，也作为嵌段共聚物以提高UPE分子的交联速度与有效性。但是苯乙烯已被确认为一种致癌物。本项目针对纤维增强不饱和聚酯复合材料制备中产生的苯乙烯释放危害人体健康问题，以改性植物油作为UPE的反应性溶剂与交联剂，以此制备大麻纤维增强UPE复合材料。对新型UPE树脂的固化过程、大麻纤维表面改性对复合材料界面特性的影响等关键科学问题进行研究，取得了初步的成果。主要工作及获得的结论如下：.1）分析了无苯乙烯UPE树脂（固态）在丙烯酸酯环氧大豆油(AESO)中的溶解性，阐述了新型UPE树脂的固化机理。研究结果表明：AESO加热到80度以上具有良好的流动性，无苯乙烯UPE树脂可以完全溶于AESO。2）以AESO为溶剂的UPE树脂在引发剂作用下，可产生自由基聚合反应，从而使树脂形成交联，可制备出力学性能优良的大麻纤维/UPE复合材料。3）对大麻纤维进行表面改性，结果显示：采用具有双功能的异氰酸酯单体，可以在大麻纤维与UPE树脂间形成共价键结合，从而改善了大麻纤维与UPE树脂之间的相容性。此外，AESO的环氧基也可能与纤维表面羟基形成共价键结合，从而在大麻纤维与UPE之间形成偶联效果，此结论有待一些表征手段的进一步证实。4）对AESO为溶剂与以苯乙烯为溶剂的UPE树脂复合材料力学性能进行了对比，结果显示：以60%质量分数AESO为溶剂的UPE树脂复合材料力学性能略高于30%质量分数的苯乙烯为溶剂的UPE树脂复合材料力学性能。5）通过复合材料界面特性分析，初步揭示了纤维/树脂间化学键形成的条件及机理。此外，本项目还分别以甘油与植物油裂解产物为原料合成UPE反应性溶剂进行了探索性研究。本项目为环境友好、低成本、高强度大麻纤维增强UPE复合材料的制备与应用提供了科学依据。这种以可再生原料制备的生物质新材料，有望部分替代玻璃纤维增强石油基树脂复合材料，用于制造电器构件、汽车内衬板等。