改性红麻纤维/棕榈油基树脂复合材料的协同制备及其界面结合机制

The large consumption of petroleum-based thermosetting resins in fiber-reinforced composites cannot meet the requirement of green and sustainable developments. The proposal aims at developing environmentally friendly palm oil-based thermosetting resins with low-costs and low-viscosity, and then the resulting resins will be used as the matrices for kenaf fibers to prepare the green bio-composites with high renewable contents. The palm oil-based resins will be synthesized through transesterification of triglycerides with alcohols and incorporation of rigid structures, which provides the solution for the problems including low crosslinking density and poor mechanical properties of the palm oil-based resins due to the intrinsic drawbacks of palm oil, i.e., low level of unsaturation. The synthesis mechanism, chemical compositions, rheological property, and curing kinetics of the new resins will be fully investigated. Kenaf fibers will be modified with palm oil through the transesterification between the hydroxyl groups of fibers and triglycerides, which induces the grafting of palm oil-based fatty acid on the fiber surface and hence increases the interfacial adhesion between fibers and matrices. The bio-composites from the modified kenaf fibers and palm oil-based thermosets will be prepared. The interfacial adhesion between the fibers and the new resins, and synergistic reinforcing effects of fiber modification and resins on mechanical properties of the kenaf fibers-reinforced palm oil-based resin composites will be studied in details. The research enables us to gain a good understanding of mechanism for the preparation and application of environmentally friendly composites from natural fibers and bio-based resins.

目前纤维增强树脂基复合材料中大量使用石油基热固性树脂，不符合可持续与绿色发展的理念。鉴于此，本项目拟采用棕榈油为原料合成环境友好、低成本、低粘度的棕榈油基热固性树脂，并以红麻纤维为增强体制备高生物基含量的“绿色”复合材料。针对棕榈油低不饱和度的本质特性而导致的树脂交联度低、力学性能差等关键问题，利用醇与甘油三酯的转酯化反应合成棕榈油基单甘酯，再引入刚性单体制备棕榈油基树脂，揭示新型棕榈油基树脂的合成机制、化学成分、化学流变性和固化动力学机理。针对红麻纤维与树脂基体的界面相容性难题，利用甘油三酯与纤维表面羟基的转酯化反应，将棕榈油脂肪酸链接枝到纤维表面。通过对改性红麻纤维/棕榈油基树脂复合材料的制备及表征，探究新型树脂与红麻纤维在复合过程中的界面结合机理，阐释树脂基体与纤维改性协同增强复合材料力学性能的机制，为环境友好、高强度植物纤维增强生物基树脂复合材料的制备和应用提供科学依据。

棕榈油是产量最大、价格最低的植物油。以棕榈油为原料开发生物质新材料可缓解当前石油资源短缺问题，符合可持续与绿色发展的理念。本项目采用棕榈油为原料合成了环境友好、低成本、低粘度的棕榈油基热固性树脂，并以植物纤维为增强体制备高生物基含量的生物质复合材料。针对棕榈油低不饱和度的本质特性而导致的树脂交联度低、力学性能差等关键问题，本项目利用棕榈油甘油三酯与N-羟乙基丙烯酰胺的酯交换反应，合成了一种可自由基聚合的棕榈油乙烯基单体（POFA-EA）；以生物质刚性单体为原料，通过无溶剂超声波辅助法合成系列生物基反应性溶剂；以生物基反应性溶剂和POFA-EA共聚制备了一系列性能优异的棕榈油基热固性树脂；通过模压成型或3D光固化打印技术制备了植物纤维增强棕榈油基树脂生物质复合材料。通过对新型棕榈油基树脂混溶性、流变性能、固化机理、力学性能的表征发现，所制备的树脂具有符合复合材料制备所需的加工性能和优异的热学和力学性能；复合材料的性能测试表明，纤维表面改性和树脂成分显著影响复合材料的动、静态力学性能和热学性能以及植物纤维与树脂的界面结合，复合材料的力学强度和模量可与传统不饱和聚酯或大豆油基树脂复合材料相媲美；所制备棕榈油基树脂的玻璃化转变温度可达200°C，不仅可用于植物纤维，同时还适合作为玻璃纤维或碳纤维的树脂基体，同时树脂基体可在弱碱性条件下发生降解，为高性能纤维的回收提供可能。项目的成果可为低不饱和度木本棕榈油的高附加值利用提供新的途径，为新型生物基复合材料的制备和应用提供科学依据。