【作者】 刘训堃；

【导师】 滕翠青； 余木火；

【作者基本信息】 东华大学 ， 材料物理与化学， 2007， 硕士

【摘要】 近年来，由于全球能源和环境问题的日益突出，采用自然界丰富的天然植物纤维，如木纤维、竹纤维、麻纤维(苎麻、亚麻、剑麻等)、椰纤维等，替代玻璃纤维和合成纤维作为树脂基复合材料的增强体逐渐受到人们的关注。然而，目前所选用的基体树脂大多是不能自然降解的合成树脂，因此天然植物纤维复合材料仍会给环境带来负担。本论文主要研究以全生物降解的聚乳酸(PLA)预聚物和聚己内酯(PCL)预聚物为原料，天然纤维苎麻织物为增强材料，采用原位聚合法制备全生物降解苎麻织物增强PLLA-PCL绿色复合材料。原位聚合是一种先进的复合材料制备方法，对于长纤或织物增强热塑性复合材料，该方法能很好的解决界面的相容性。本文中是用熔融缩聚法制备低分子量的PLLA预聚体及PCL预聚体，用预聚体浸润增强纤维，再通过原位聚合的方法制备出苎麻织物增强PLLA-PCL复合材料。该聚合方法通过低粘度的预聚物浸润增强纤维，避免了传统的高分子量的树脂基体浸润增强纤维困难的问题，获得了非常良好的界面相容性。本论文主要研究的内容：1．研究了硅烷偶联剂KH550和KH560对苎麻织物的表面处理。FTIR、SEM、接触角及吸水率等测试结果表明：KH550和KH560处理苎麻织物的最佳时间和浓度分别为30min和1％。处理后苎麻的亲水性和吸水率明显下降，但同时力学性能有所下降。而且，KH550的处理效果要优于KH560。2．研究了PLLA预聚体与PCL预聚体的溶液聚合，结果表明，当反应温度为80℃反应时间为4h，所得PLLA-PCL共聚物分子量最高。通过DSC、TGA对共聚物的薄膜研究发现，该聚合物有着良好的热性能。3．研究了模压成型条件对苎麻增强PLLA-PCL复合材料力学性能的影响，其最佳模压工艺为170℃，预热10min、保压5min。4．研究了苎麻含量、苎麻预处理对复合材料力学性能的影响。使用KH550处理，苎麻含量为45％时，其拉伸强度、缺口冲击强度和弯曲强度分别达到68.95MPa、53.54J／m~2和75.06MPa，具有实际应用价值。5．采用SEM分析了复合材料的界面。结果表明，在原位聚合法制备苎麻织物增强PLLA-PCL复合材料的过程中，基体树脂中的异氰酸酯基团与偶联剂KH550的胺基官能团反应从而接枝到苎麻织物表面，使苎麻织物与基体树脂之间形成良好的界面粘结，从而大大提高了复合材料的力学性能。更多还原

【Abstract】 With a greater concern for environmental protection, natural fibers such as ramie fiber, flax fiber, jute fiber, bamboo fiber and wood fibers as reinforcement in plastics have increased dramatically during the last few years. But most the matrix of the natural fibers reinforced composites were not biodegradable resin, the composites also took destruction to the environment.In this study, natural ramie fabric reinforced PLLA-PCL copolymer composites prepared by in-situ polymerization. This kind of composites is full biodegradable material, with high mechanical performance and expected as having broad application in many fields.Recently, the in-situ polymerization process to manufacture the long fiber reinforced thermoplastic composite is carried out in our laboratory to explore a new process which will have effective impregnation and be suitable for most thermoplastic matrix resin. In this new process, the reinforcing fabrics are impregnated in the oligomers of PLLA and PCL, finally the oligomer in the prepreg is in-situ polymerized to form the high molecular weight matrix.The research works and main conclusions were summarized as following:1. Ramie fabric surface modification with KH550 and KH560 was studied and the results showed that KH550 is better than KH560 on the surface modification of ramie fabric. The optimum time and concentration of KH550 or KH560 were 30min and 1%. After treating with KH550 or KH560, the hydrophilic of ramie fabric was reduced obviously, but the mechanical properties of ramie fabric reduced a little.2. The PLLA oligomers and PCL oligomers was synthesized in solution. The molecular weight of the PLLA-PCL eopolymers reached a maximum value when the reaction was carried at 80℃for 4h. The DSC and TGA was used to characterize the thermal stability of the copolymers and the result shows the copolymers has excellent thermal stability.3. The effect of moulding temperature and time on the mechanical properties of ramie fabric reinforced PLLA-PCL composites was studied. The results indicated that the mechanical properties of composites reached a maximum value under 170℃, warm-up 10min, pressing 5 min.4. The effect of ramie fabric content and its surface modification on the mechanical properties of composites was studied. When the fabric content was 45% and the fabric was treated with KH550, the composites showed the best mechanical performance, the tensile strength, impact strength and flexural strength were 68.95MPa, 53.54 J/m² and 75.06MPa respectively.5. During in-situ polymerization process, the - NCO groups at the end of PCL oligomers could react with - NH₂ groups of KH550, therefore the resin was grafted to the surface of ramie fabric, and which was beneficial to form good interfacial adhension between ramie fabric and PLLA-PCL.更多还原