懸浮聚合法製備相轉移材料微膠囊; Preparation of Phase Change Materials Microcapsules by Suspension Polymerization

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Title:	懸浮聚合法製備相轉移材料微膠囊;Preparation of Phase Change Materials Microcapsules by Suspension Polymerization
Authors:	楊雯欣;Wen-hsin Yang
Contributors:	化學工程與材料工程研究所
Keywords:	懸浮聚合法;相轉移材料;微膠囊;Phase change materials;Microcapsule;Suspension polymerization
Date:	2007-06-08
Issue Date:	2009-09-21 12:27:56 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	本研究以甲基丙烯酸甲酯(MMA)為單體，乙二醇二甲基丙烯酸(EGDMA)為交聯劑，過氧十二醯(LPO)為起始劑，並以聚乙烯醇(PVA)作為穩定劑，利用懸浮聚合法包覆熔點為28 ºC之正十八烷，此外亦於上述系統中分別導入親水性單體(MAA)、親油性單體(MA)和無機物(TEOS)，因而製備出利用PMMA架橋體、P(MAA-MMA)架橋體、P(MA-MMA)架橋體以及PMMA架橋體-二氧化矽混成材料作為殼物質之相轉移材料微膠囊，所製得之微膠囊則使用SEM觀察其粒徑大小和表面結構、DSC量測其潛熱值和正十八烷包覆率以及TGA分析其熱性質。　　實驗結果顯示利用PMMA架橋體作為殼物質時，增加起始劑和架橋劑的濃度、提高反應的溫度或是延長高溫的反應時間，都可使微膠囊所包覆的正十八烷含量提升，而隨著穩定劑濃度的增加，粒俓會有變小的趨勢，在此方法中相轉移材料微膠囊最佳的核/殼比例為1/1，粒徑約在0.5 μm - 2.5 μm，潛熱值為105.2 J/g，產物產率為66.6%，正十八烷的包覆率則為69.4%。　　當系統中導入MAA後，正十八烷的包覆率能增加至72.1%，但卻造成產率下降至48.1%，但是藉由在聚合反應進行至22小時後導入水溶性起始劑(V50)，可使得產物產率和正十八烷的包覆率分別提升至68.4%和79.0%，另外，唯有當MAA重量百分比為5%時，才能使得微膠囊的耐熱性提升。　　當系統中導入MA後，對於產物的產率、正十八烷的包覆率和耐熱性並無明顯提升的效果，但是藉由在均質前導入V50，卻可使得產物產率和正十八烷的包覆率分別提升至81.2%和78.2%。　　在酸性環境中導入無機物於系統後，無機物含量的增加雖可提高產率和正十八烷的包覆率，但過多時卻易造成微膠囊球體凹陷，另外藉由在系統中添加鹽酸而調整系統之pH，亦可使得產率和正十八烷的包覆率增加。當無機物的添加量為5%，且添加之鹽酸含量相對於系統中的水換算而得到之pH値為1.09時，產物產率和正十八烷的包覆率會分別提升至73.4%和83.1%。 Encapsulation of phase change materials (PCM), n-octadecane melted at 28 oC, by using acrylic series networks as the shell materials have been developed. The effects of the various process parameters including the concentration of initiator, the concentration of EGDMA, the polymerization temperature, the reaction time, the weight ratio of core/shell, the weight fraction of MAA, the weight fraction of MA, the weight fraction of SiO2 and the different pH of water were investigated. The influence of above parameters on diameters, morphologies, thermal energy storage/release capacities and thermal stabilities of the microcapsules were characterized by scanning electron microscope (SEM), differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA). The results showed that the diameters of PCMs microcapsules were in the range of 0.5-3.0 μm. Latent heat of PCM microcapsules were above 90 J/g. The best core/shell weight ratio was 1/1. The efficiency of encapsulation was improved by increasing initiator concentration, polymerization temperature, reaction time in higher temperature and EGDMA concentration. In addition, the efficiency of encapsulation was also promoted by introducing the suitable amount of MAA, MA and TEOS in the system.
Appears in Collections:	[National Central University Department of Chemical & Materials Engineering] Electronic Thesis & Dissertation

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