纳米纤维素功能化改性及其在复合材料中的应用研究

发布时间：2018-03-31 00:34

  本文选题：纳米纤维素　切入点：气凝胶　出处：《青岛科技大学》2017年硕士论文

【摘要】：纳米纤维素作为一种纳米尺度的纤维素聚集体,具有高结晶度、高杨氏模量、高强度等特性,同时还具有良好的生物相容性、可降解、无毒以及可再生等特点。纳米纤维素作为一种绿色的增强材料受到越来越多的关注,在制备高性能纳米复合材料中具有巨大的应用前景。纳米纤维素表面存在大量的羟基,能够形成强氢键作用,同时表面存在的羟基使其易于化学改性。本文采用物理法制备了纳米纤维素纤丝(NCFs),采用化学法制备了纳米纤维素晶体(CNCs)。以NCFs为原料制备了气凝胶,以CNCs为填料提高了双组份水性聚氨酯(2K-WPU)和室温硫化硅橡胶(RTV)的性能。以NCFs为原料,使其在四氯化锡的催化下与1,4-丁二醇二缩水甘油醚(BDGE)发生交联反应而制备了多孔的纳米纤维素气凝胶。制备的纳米纤维素气凝胶具有连续的多孔网络结构,仍保持纤维素I型结构,初始分解温度在300℃以上。BDGE的添加量为NCFs质量的2倍时,制备的气凝胶密度为0.0202mg/cm3,吸水倍数为36 g·g-1,气凝胶在水和DMSO中能恢复形变的90%以上,重复使用5次,吸水倍数仍高达30 g·g-1。以CNCs为填料提高双组份水性聚氨酯(2K-WPU)的性能,考察了2K-WPU/CNCs纳米复合材料的形貌结构、热力学性能和机械性能。结果表明CNCs与2K-WPU相容性好且CNCs在聚合物基质中均匀分散。CNCs作为填料显著的提高了2K-WPU的拉伸强度,随着CNCs含量由0%增加至9%,2K-WPU/CNCs复合材料的拉伸强度由2.63 MPa增加至10.22 MPa,提高了288.6%,断裂伸长率由644.3%下降至87.2%。随着CNCs用量的增加,热稳定性和玻璃化转变温度也有所上升。此外,本文还利用氨基甲酸酯化反应对CNCs的表面进行功能化改性,采用3-异氰酸酯基丙基三甲氧基硅烷提高CNCs在RTV基质中的分散性,制备的硅氧烷化纳米纤维素晶体(SCNCs)与商业硅橡胶0混合均匀后室温硫化。SCNCs对RTV具有较强的增强作用,仅添加质量分数3%的SCNCs,纳米复合材料的拉伸强度由0.46 MPa上升至1.45 MPa,提高了215.2%,断裂伸长率由493.4%下降至444.0%,下降了9.9%。随着SCNCs含量的增加,热稳定性明显提高。
[Abstract]:As a kind of nano-scale cellulose aggregates, nano-cellulose has the characteristics of high crystallinity, high Young's modulus and high strength, and also has good biocompatibility and biodegradability. As a green reinforcing material, nano-cellulose has attracted more and more attention, and has a great application prospect in the preparation of high-performance nanocomposites. There are a lot of hydroxyl groups on the surface of nano-cellulose. In this paper, nanocellulose fibers were prepared by physical method, nanocellulose crystals were prepared by chemical method, aerogels were prepared using NCFs as raw material. The properties of two-component waterborne polyurethane 2K-WPUand room temperature vulcanized silicone rubber were improved by using CNCs as filler. NCFs was used as raw material. The porous nano-cellulose aerogels were prepared by the crosslinking reaction of stannous tetrachloride with 1,4-butanediol diglycidyl ether BDGE.The prepared nanocellulose aerogels have continuous porous network structure. When the initial decomposition temperature is above 300 鈩，

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