竹原纤维/生物质基树脂复合材料的制备机理及其细观力学性能预测

Natural plant fibers reinforced polymer composites have received considerable concerns in recent years. Natural plant fibers have advantages such as high specific strength and modulus, economical availability, and biodegradability over inorganic or synthetic fibers for reinforcing polymers. In this proposal, we focus on developing styrene-free unsaturated polyester (UPE) and acrylated epoxy soybean oil (AESO) based resins, and providing solution for the problems of styrene emission and spreading of fine glass fibers in the air during the manufacture of glass-fiber reinforced UPE composites. Also, due to their high specific strength and stiffness, original bamboo fibers which were mechanically extracted from moso bamboo culm were adopted to replace glass fibers as reinforcement for preparing UPE and AESO composites. Novel reactive diluents using bio-based polylol as raw materials will be synthesized. Styrene-free UPE and AESO-based resins with novel reactive diluents will be prepared and evaluated in terms of their mechanical properties and water resistance, respectively. The mechanism of crosslinking between the novel diluents and UPE/AESO resins will be revealed. Surface modification of bamboo fibers with novel bio-based copolymers will be conducted to improve the interfacial adhesion between the fibers and resins. The comprehensive characterization methods of composite interfacial adhesion will be developed. The mechanism of the chemical bonding formed among fibers, compatibilizers and resins will be investigated. . On the other hand, due to the fact that the prediction of mesomechanics-performance is the foundation of integrated design of composite materials and structures, the multi-scale prediction method for bamboo-fibers/UPE composites with periodic microstructures will be developed, thus establishing the strength failure rule for such randomly oriented bamboo-fibers/UPE composites.. The feedstocks of the proposed modifiers for bamboo fibers and resins, polylol and AESO, are all renewable and environmentally friendly. The use of the novel reactive diluents and modifiers for bamboo-fibers/UPE composites will significantly reduce the hazardous substances released from composites plants where styrene-based UPE resins and glass fibers are still used as raw materials. The proposed novel bio-based composites have advantages including high biomass content, specific strength and modulus, environmentally friendly, and low cost of preparation, and will be applied widely in many fields.

针对玻璃纤维增强不饱和聚酯复合材料制备过程中产生的吸入性玻纤及挥发性苯乙烯危害人体健康的难题，分别以多元醇和改性大豆油等生物质基原料，合成多种不饱和聚酯的反应性溶剂及大豆油基热固性树脂；揭示新型溶剂不饱和聚酯与大豆油基树脂固化过程的反应机理。针对竹纤维/树脂复合材料关键基础科学问题——界面性能及其表征，对机械法制备的竹原纤维进行表面化学改性，把具有高度不饱和双键的生物基共聚物引入到复合体系中，从而改善纤维与树脂基体之间相容性，进而阐明纤维与基体改性在材料复合过程中的作用以及纤维/基体间化学键合的条件及机理。采用多尺度方法对随机分布竹原纤维复合材料细观力学性能进行预测，为竹原纤维/不饱和聚酯复合材料结构——性能的一体化设计及应用提供科学基础。制备的竹原纤维复合材料具有高生物质基含量、环境友好、成本低、比强度及比模量高等优势，应用前景广阔。

项目针对玻璃纤维增强不饱和聚酯复合材料制备过程中产生的吸入性玻纤及大量使用挥发性溶剂苯乙烯危害人体健康的难题，分别以多元醇和改性大豆油等生物质基原料，合成了多种不饱和聚酯的反应性溶剂及大豆油基热固性树脂。围绕竹纤维/树脂复合材料关键基础科学问题——界面性能及其表征，提出转酯化法提高树脂反应活性、无溶剂法合成生物基反应性溶剂、原位界面增容等策略，解决生物基树脂合成与制备、树脂加工性能优化、复合材料界面优化及性能提高等技术难题，进而改善纤维与树脂基体之间相容性，阐明了纤维与基体改性在材料复合过程中的作用以及纤维/基体间化学键合的条件及机理。采用多尺度方法对随机分布竹原纤维复合材料细观力学性能进行预测，为竹原纤维/不饱和聚酯复合材料结构——性能的一体化设计及应用提供科学基础。.主要研究内容及取得的成果包括：1）针对环氧大豆油丙烯酸酯（AESO）树脂粘度大、交联密度低的应用难题，合成或选用了系列多官能团单体作为AESO树脂的反应性溶剂，突破了高性能且生物基含量高的竹纤维增强AESO复合材料的关键技术。2）以废弃PET纤维、竹纤维和大豆油为原料，成功开发了无苯乙烯PET混杂纤维增强AESO复合材料，该材料可在高温水相中降解并可回收纤维增强体，实现了由回收材料到可降解材料的绿色循环。3）基于动态硫化技术提出了添加阳离子引发剂或生物基刚性单体的方法，诱导环氧大豆油（ESO）的环氧基进行开环聚合，提出了全生物基高韧性的ESO/聚乳酸共混物的制备路线与技术方法，同时巧妙设计了大豆油橡胶相在竹纤维/聚乳酸复合材料内部的均匀分布，协同调控复合材料的力学强度与韧性平衡。.以竹纤维增强AESO复合材料为例，其性能指标：拉伸强度82MPa、弯曲强度125MPa、弯曲弹性模量6240MPa、含水率1.4%、24h吸水厚度膨胀率2.6%；该复合材料具有原料来源可再生、力学性能和耐水性优异的优点。