纤维素醚基固—固相变膜的制备及其性能研究

发布时间：2018-01-06 17:06

本文关键词：纤维素醚基固—固相变膜的制备及其性能研究　出处：《北京理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：随着世界石油资源的紧缺、能源危机日渐加深、环境污染日益严重,环境友好的相变储能材料受到了广泛关注。聚乙二醇(PEG)作为最常用的相变材料,其具有结构简单,容易结晶,相转变潜热高,热滞后效应低等优点,但其属于固-液相转变材料,限制了其在相变材料中的应用,经过处理改性后,PEG可以转变为固-固相转变材料。本文利用来源丰富、价格低廉、可生物降解、生物相容性好的纤维素醚类作为基体和骨架,通过与PEG大分子间的氢键作用,利用物理共混法制备了纤维素醚基固-固相变膜,并对不同共混比的相变膜进行了测试分析。同时通过添加纤维素纳米纤维(CNFs)对相变膜进行改性,优化相变膜性能。首先以离子型纤维素醚——羧甲基纤维素(CMC)为基体材料,制备了PEG-CMC固-固相变膜。研究发现:CMC通过氢键对PEG的束缚作用不是十分理想,在该相变膜中PEG最高添加量为30%,随着PEG添加量增大,相变膜的热稳定性未受显著影响,透光率下降,相变焓增大,断裂强度降低,断裂伸长率升高。在此基础上,论文以非离子型纤维素醚——羟丙基甲基纤维素(HPMC)作为基体材料,制备了PEG-HPMC固-固相变膜。研究发现:HPMC通过氢键对PEG的束缚作用有所提高,在该相变膜中PEG最高添加量达到40%,随着PEG添加量的增大,相变膜的热稳定性、相变焓均有所增强,断裂强度逐渐降低,断裂伸长率先升高后降低,但其透光率受到了显著影响,PEG添加量在20%及以上时,相变膜在可见光波长范围内透光率为0%。为了提高固-固相变膜的整体性能,论文又以CNFs作为改性填料,添加至PEG-HPMC固-固相变膜中,制备了PEG-HPMC-CNFs固-固相变膜。研究发现:CNFs的添加对相变膜的热稳定性及相变焓影响不大,但其有效改善了相变膜的透光率,当CNFs添加量为2%~4%时,相变膜的在可见光波长范围内的透光率为80%,同时断裂强度及断裂伸长率在CNFs添加量为3%时显著提高。
[Abstract]:With the shortage of petroleum resources in the world, the energy crisis is deepening day by day, the environmental pollution is becoming more and more serious, and the environmentally friendly phase change energy storage materials have received extensive attention. Polyethylene glycol (PEG) is the most commonly used phase change material. It has the advantages of simple structure, easy crystallization, high latent heat of phase transition and low thermal hysteresis effect. However, it is a solid-liquid phase transition material, which limits its application in phase change materials. PEG can be transformed into solid-solid phase transition materials. Cellulose ethers, which are rich in source, cheap, biodegradable and biocompatible, are used as matrix and skeleton in this paper. Cellulose ether based solid-solid phase film was prepared by physical blending method through hydrogen bonding with PEG macromolecules. The phase change films with different blending ratios were tested and analyzed, and the phase change films were modified by adding cellulose nanofibers (CNFs). The performance of phase change film was optimized. Firstly, the ionic cellulose ether-carboxymethyl cellulose (CMC) was used as the matrix material. Solid-solid phase change film of PEG-CMC was prepared. It was found that the binding effect of PEG on PEG by hydrogen bond was not ideal. The maximum addition of PEG in the film was 30%. With the increase of PEG content, the thermal stability of the phase change film is not significantly affected, the transmittance decreases, the phase transition enthalpy increases, the fracture strength decreases, and the elongation at break increases. Nonionic cellulose ether-hydroxypropyl methyl cellulose (HPMC) was used as matrix material. The solid-solid phase change film of PEG-HPMC was prepared. It was found that the binding effect of PEG on PEG was improved by hydrogen bond. The maximum addition of PEG in the film was 40%. With the increase of PEG content, the thermal stability and phase transition enthalpy of the phase change film increased, the fracture strength gradually decreased, the elongation at break increased first and then decreased, but its transmittance was significantly affected. When the amount of PEG is 20% or more, the transmittance of phase change film is 0 in the range of visible wavelength. In order to improve the overall performance of solid-solid phase change film, CNFs is used as the modified filler in this paper. It was added to PEG-HPMC solid-solid phase film. Solid-solid phase change films of PEG-HPMC-CNFs were prepared. It was found that the addition of PEG-HPMC-CNFs had little effect on the thermal stability and enthalpy of phase transition, but it could effectively improve the transmittance of phase change films. When the amount of CNFs is 2 ~ 4, the transmittance of the phase change film in the visible wavelength range is 80, and the fracture strength and elongation at break are significantly increased when the addition amount of CNFs is 3.
【学位授予单位】：北京理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB34

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