【作者】 王志强；

【导师】 马文石；

【作者基本信息】 华南理工大学 ， 材料学， 2020， 硕士

【摘要】 社会发展及传统石化能源的消耗导致的环境问题日趋严重,使得科研人员致力于新能源的开发与利用。相变材料不仅是一种可以存储及释放能量的新型材料,而且环保无害,越来越备受关注。但是纯的相变材料在其使用过程中会有相态的变化及热导率低等问题,导致其使用受限。针对这一问题,科研工作者研究了微胶囊化相变材料这一技术。目前研究最多的是以聚合物为壁材,有机相变材料为芯材的相变微胶囊。但是以聚合物为壁材的相变微胶囊的致密性差及过冷现象限制了它的应用。本课题主要针对传统相变微胶囊致密性差及存在过冷现象等问题,进行以下研究:(1)由于相变微胶囊的粒径越大,其致密性越好,为此本文采用聚氨酯预聚物与多元醇之间在水包油乳液中的界面聚合法制备了一种以聚氨酯为壁材的大粒径相变微胶囊。实验结果表明,利用聚氨酯预聚体能合成平均粒径大于100μm的相变微胶囊,当转速从200 rpm增加至500 rpm时,相变微胶囊的粒径由433μm降至63.3μm,高温下失重率从10.47 wt%升高到43.49 wt%,致密性变差了。PEG含量为20 wt%-30 wt%时可以获得力学性能较好的相变微胶囊,且当芯壁比为3:1时,其芯材含量高达75.18%同时具有良好的热稳定性和储存稳定性。(2)利用Pickering乳液聚合法制备了一种聚氨酯相变微胶囊。结果表明,Pickering乳液聚合法制备出的相变微胶囊平均粒径也大于100μm,在一定纳米二氧化钛浓度的Pickering乳液中制备出的相变微胶囊的致密性,力学性能及热稳定性较好,并展示出良好的热循环稳定性、化学稳定性和存储稳定性。DSC结果表明,纳米二氧化钛浓度的变化会影响相变微胶囊的相变行为,当纳米二氧化钛浓度由增加0.03%增加至0.24%,相变材料均相成核的温度由-20.96℃升高到-18.35℃。(3)以固体石蜡代替部分芯材,采用界面聚合法制备了一种包覆混合芯材的聚氨酯相变微胶囊,研究了相变微胶囊的相关性能。结果表明固体石蜡的添加并不会改变相变微胶囊的化学结构、力学性能、致密性、粒径分布和热稳定性,但相变微胶囊相变行为受到了一定影响。当固体石蜡含量由0增加至4%时,相变微胶囊中月桂酸甲酯的凝固点由-19.83℃升高至-10.12℃,热存储能力相对降低了21.4%。更多还原

【Abstract】 The increasing seriousness environmental problems caused by the development of society and the consumption of traditional petrochemical energy makes researchers devote themselves to the development and utilization of new energy.Phase change materials are not only a new type of materials which can store and release energy,but also environmentally friendly and harmless,more and more attention have been paid to it.However,the direct use of pure phase change materials are limited due to the change of phase state and low thermal conductivity.In order to solve this problem,the technology of microencapsulated phase change materials（MEPCMs）have been developed by researches.At present,the most studied are MEPCMs with polymer as shell materials and organic phase change material as core material.But the poor compactness and supercooling of MEPCMs with polymer shell materials limit its application.This paper mainly focuses on the problems such as poor compactness and supercooling of traditional MEPCMs with polymer shell materials.（1）The larger the size of MEPCMs,the better the compactness.Therefore,a large size MEPCMs with polyurethane（PU）as shell material was synthesized by interfacial polymerization between polyurethane prepolymer and polyol in oil-in-water emulsions.The results showed that the employment of the synthesized PU prepolymer was beneficial to synthesize the MEPCMs with more than 100μm average particle size,when the agitation speed increased from 200 rpm to 500 rpm,the diameter of MEPCMs decreased from 433μm to 63.3μm,but the weight loss of MEPCMs increased from 10.47 wt%to 43.49 wt%at high temperature,the compactness became worse.The MEPCMs with better mechanical properties can be obtained with PEG content of 20 wt%-30wt%in the prepolymer,and when the core/shell mass ratio was 3:1,the core material content of MEPCMs was as high as 75.18%,and showed good thermal stability and storage stability.（2）PU MEPCMs were prepared by Pickering emulsion polymerization.The results showed that average particle size of MEPCMs prepared by Pickering emulsion polymerization was also more than 100μm.The MEPCMs prepared at a certain nano-Ti O₂concentration had good compactness,mechanical properties and thermal stability and possessed promising thermal cycling stability,chemical stability and storage stability.The DSC results showed that the change of nano-Ti O₂concentration would affect the phase change behaviors of MEPCMs,the temperature of heterogeneous nucleation of phase change materials increased from-20.96℃to-18.35℃with the nano-Ti O₂concentration increased from 0.03%to 0.24%.（3）PU MEPCMs containing mixed core materials were prepared through interfacial polymerization by adding solid paraffin replacing part methyl laurate,and the related properties of MEPCMs were studied.The results showed that the chemical structure,the mechanical properties,compactness,particle size distribution and thermal stability of MEPCMs were not influenced by the addition of solid paraffin,but the phase change behavior of MEPCMs was affected.When the solid paraffin content increased 0 to 4%,the freezing point of methyl laurate in MEPCMs increased from-19.83℃to-10.12℃,but the thermal storage capacity reduced by 21.4%relatively.更多还原