Preparation and characterization of polyurea/polyurethane double‐shell microcapsules containing butyl stearate through interfacial polymerization

Double‐shell microcapsules containing butyl stearate were prepared through interfacial polymerization. The outer shell is polyurea formed through polymerization of toluene‐2,4‐diisocyanate (TDI) and diethylene triamine, and the inner shell is polyurethane (PU) formed through polymerization of TDI and polypropylene glycol 2000 (PPG2000). Styrene maleic anhydride copolymer was used as emulsifier. The effects of core to monomer ratio and dosage of PPG2000 on core content and encapsulation efficiency of microcapsules were investigated. The core content has a maximum at core to monomer ratio of 3–4, and the encapsulation efficiency has a maximum value of 95% at core to monomer ratio of 2. The prepared microcapsules were smooth and compact and have an obvious latent heat of 85 J/g. The shell structure of microcapsules was polyurea and PU. The average diameter of the microcapsules was 1–5 μm. The stabilities of the double‐shell microcapsule, such as anti‐ethanol wash and antiheat properties are obviously improved than those of single‐shell microcapsule. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Fabrication and thermal properties of microPCMs: Used melamine‐formaldehyde resin as shell material

An in‐situ polymerization process prepared a series of melamine formaldehyde (MF) microcapsules containing phase change material (PCM) as core material. The phase change temperature of this PCM was 24°C and its phase transition heat was 225.5 J/g. The microencapsulated phase change materials (MicroPCMs) were bedded in indoor‐wall materials to store and release heat energy, which would economize heat energy and make the in‐door condition comfortable. We investigated the structural formation mechanism by microscope and scanning electron microscopy (SEM). The superficial morphology measurements indicated the optimal shell material dropping rate 0.5 mL min^?1, double‐shell, and temperature elevating speed 2°C/10 min. The results obtained in the present investigation were reasonably understood on the basis of getting determinate rigidity and compacted shell. Also, the observed results were used to control the mass of shell material to get desired thickness of shell. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 2006     

一种蜜胺树脂为壁材的相变储热微胶囊致密性研究

采用原位聚合法用蜜胺树脂包覆了一种相变点为24℃,相变热为225 5J/g的有机复合相变材料,并对所制备的相变储热微胶囊的致密性进行了研究。利用扫描电子显微镜对微胶囊的表面形态进行了观察;用722型分光光度计对不同工艺条件下所得微胶囊在密度为0.79g/mL乙醇中的渗透性进行了研究;采用压力法观察微胶囊在受压后的表面形貌,对其强度进行了评价。结果表明:相变储热微胶囊呈均匀的球形,表面光滑且致密,平均粒径110μm;由于蜜胺树脂有大的交联密度,微胶囊在乙醇中渗透缓慢,证明芯材包覆效果好,同时发现双层壁材微胶囊的致密性优于单层壁材的微胶囊;平均粒径为10μm的优于平均粒径为1μm的;随着壁材用量的增大,渗透性减弱,但为了保证相变储热微胶囊的储热效果,芯材与壁材质量比以3为好。所制备的微胶囊可以承受1 96×105Pa的压力而不破损。     

含相变材料的定型复合建材储能调温及力学特性

使用微胶囊化和直接吸附法两种方式将相变材料与水泥结合分别制成了含相变微胶囊水泥基复合建材及含相变材料水泥基复合建材,搭建实验测试系统,对复合建材的调温储能特性进行了测试。微胶囊化相变材料和纯相变材料的加入对水泥基建材的微观结构形貌具有较为明显的影响。热重曲线显示纯水泥、相变微胶囊-水泥、相变材料-水泥试样的失重率依次增加,相变微胶囊-水泥式样的稳定性最好;复合成分所占质量分数相同时,相变材料-水泥试块强度略低于相变微胶囊-水泥试块;调温测试表明,在水泥中添加相变微胶囊颗粒或纯相变材料时均具有一定的调温储能功能,能明显减缓水泥基建材的温度在相变温度附近的波动;尽管直接吸附法制备的相变材料-水泥复合建材具有较好的调温性能,但其可循环性较差,伴有刺激性气味逸出,实用性较差。因此相变微胶囊-水泥复合较适宜作为新型建材推广使用。     

Preparation of phase change materials microcapsules by using PMMA network‐silica hybrid shell via sol‐gel process

Encapsulation of phase change materials (PCM) using a poly(methyl methacrylate) network‐silica hybrid as the shell material has been developed. n‐Octadecane melted at 28°C was used as PCM. Based on the suspension polymerization process, the microcapsules were prepared successfully by mixing and by the reaction of ethylene glycol dimethacrylate with precopolymer solution with tetraethoxysilane (TEOS), whose resultant microcapsules had higher latent heat (ΔH = 151 J/g) than those without TEOS (ΔH = 88.3 J/g). The average size of the PCM microcapsules was about 10 μm. The silica content, n‐octadecane content, and latent heat of microcapsules were changed with varying ageing conditions, ageing time, and temperature. The highest amount of latent heat (ΔH = 178.9 J/g) and n‐octadecane content (73.3%) of the microcapsule were obtained when the inorganic/organic ratio of the microcapsule was 5%. It was difficult to increase n‐octadecane content (74% to 55.7–67.9%) and latent heat (180.5 J/g to 135.9–165.7 J/g) of the microcapsules by introducing different functional groups of coupling agents. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Preparation and characterization of polyurethane microcapsules containing n‐octadecane with styrene‐maleic anhydride as a surfactant by interfacial polycondensation

A series of polyurethane microcapsules containing a phase change material (PCM) of n‐octadecane was successfully synthesized by an interfacial polymerization in aqueous styrene‐maleic anhydride (SMA) dispersion with diethylene triamine (DETA) as a chain extender reacting with toluene‐2,4‐diisocyanate (TDI). The average diameter of microPCMs is in the range of 5–10 μm under the stirring speed of 3000–4000 rpm. Optical and SEM morphologies of microPCMs had ensured that the shell was regularly fabricated with the influence of SMA. FTIR results confirmed that the shell material was polyurethane and the SMA chains associated on core material reacted with TDI forming a part of shell material. The shell thickness was decreasing in the range of 0.31–0.55 μm with the molar ratio of DETA/TDI from 0.84 to 1.35 and the weight of core material increasing from 40 to 80% (wt %). By controlling the weight ratio of PCM as 40, 50, 60, 70, and 80% in microPCMs, it was found using DSC that the T_m and T_c of microPCMs were in the range of 29.8–31.0^oC and 21.1–22.0°C and an obvious phase change had been achieved nearly the same temperature range of that of PCM. The results from release curves of microPCM samples prepared by 1.4, 1.7, and 2.0 g of SMA indicated the release properties were affected by the amount of the dispersant, which attributed to the emulsion effect and shell polymerization structure. The above results suggest that the shell structure of microPCMs can be controlled and the properties of microPCMs determined by shell will perform proper practical usage. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4996–5006, 2006     

石蜡微胶囊型相变储能材料制备及表征

采用原位聚合法以30#石蜡为芯材、密胺树脂（MF）为囊材,制备了具有相变储热功能的微胶囊,并将所制得微胶囊添加到石膏板中。采用SEM、FTIR、DSC和TG等手段对微胶囊外观形貌、化学结构和热性能进行了表征,并测试了石膏板储能性能。结果表明：制得微胶囊中石蜡平均含量约为50.4%,相变温度和相变潜热分别为30℃、108.7 J/g;微胶囊表面光滑有突起,粒径在10～20μm;具有较好的外观结构和良好的热稳定性,能增强石膏板的保温性能。     

微胶囊复合相变材料的制备及性能表征

以低熔点的相变材料为芯材,三聚氰胺脲醛树脂为囊壁材料,用原位聚合法制备了相变储能微胶囊。采用红外光谱、扫描电子显微镜、差示扫描量热分析和热重分析测试技术表征了制备的相变微胶囊的结构组成、形貌特征及热性能。实验结果表明,相变储能微胶囊复合相变材料热稳定性好,在160℃以下无质量损失,其相变温度和焓值分别为15.3℃,132.3 J/g。制备得到的微胶囊呈球形,平均粒径小于20μm,固化剂滴加速度为0.5 mL/m in时微胶囊形貌较佳,优化的芯/壁质量比为1∶1.5,且微胶囊的亲水性随芯材含量增加而降低。     

相变储能调温内墙涂料的研制

以三聚氰胺-甲醛(MF)树脂为壁材,硬脂酸丁酯-正十四醇混合物为相变芯材制备了微胶囊相变材料,与一定比例的成膜物质混合制得相变储能调温内墙涂料。采用SEM、DSC、FT-IR等测试仪器分别对微胶囊形态、热性能、化学成分进行了表征;采用自制模型对影响涂料的储能调温效果的因素进行了分析。结果表明:所得微胶囊呈粒状、热稳定性好、相变潜热高;微胶囊的芯壁比为1.2∶1、涂层厚度为1.0 mm时,所制涂料储能调温效果最佳。     

种子微悬浮聚合法制备微胶囊相变材料

以苯乙烯(St)和二乙烯基苯(DVB)为壁材聚合单体,偶氮二异丁腈(AIBN)为引发剂,羟丙基纤维素(HPC)和碳酸钙(Ca CO3)为复合分散剂,用种子微悬浮聚合法制备交联聚苯乙烯(PS)包覆硬脂酸丁酯微胶囊。用扫描电子显微镜(SEM)、差示扫描热量仪(DSC)、粒度分析仪和热重分析仪(TG)表征了微胶囊的形貌和性能,考察了聚合方法、交联剂和分散剂对微胶囊形貌结构和性能的影响。结果表明,种子微悬浮聚合法制备的微胶囊呈粒径分布均匀、规整的球形结构,与常规悬浮聚合法制备的微胶囊相比,相变潜热提高了41.6%,包覆率提高15.1%;随着DVB用量的增加,壁材的交联度增大,微胶囊密封性和热稳定性提高;采用复合分散剂且m(HPC)∶m(CaCO_3)=2.2∶1时,微胶囊相变潜热提高了26.8%。     

复合蓄热材料的研制与应用

以KAl(SO4)2·12H2O为相变材料,以多孔陶瓷为基体,采用熔融浸渍法制备了复合相变蓄热材料。此复合相变材料结合了潜热蓄热材料与显热蓄热材料的优点,并克服了无机盐相变材料相变过程无定型的缺点及陶瓷蓄热显热小的缺点。将自制的复合蓄热材料实际应用于咖啡壶加热设备中,实验结果表明加入复合蓄热材料后的咖啡壶每小时节能率达38.8%。     

Preparation and characterization core‐shell particles and application for E‐Ink

the core‐shell particles were prepared by dispersion copolymerization. The core‐shell particles were characterized with Fourier‐transform infrared spectroscopy, Transmission electron microscope and scanning electron microscope. The dispersion stability and electrophoretic performance of core‐shell particles were studied in the mixed medium of tetrachloroethylene and cyclohexance. Microcapsules containing the core‐shell particles were prepared by coacervation. Results showed that the core‐shell particles had good dispersion stability and it had no electric response, which could be used as grounding particles for E‐Ink. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1195–1199, 2007     

复合相变蓄热材料研制及性能分析

制备了一种复合相变蓄热材料,该蓄热材料是由两种相变材料(硬脂酸和石蜡油)组成,通过物理吸附的方法将其复合在固态支撑材料中,通过实验分析了所研制的蓄热材料的相变点、相变热、热稳定性及微相结构等性能。测试结果表明该蓄热材料具有较高的相变潜热和较好的热稳定性。     

硬脂酸/活化凹凸棒石复合相变储热材料的制备与表征

以热活化的甘肃临泽凹凸棒石为基体,采用热熔法和浸渍法制备了硬脂酸/活化凹凸棒石复合相变储热材料。利用红外光谱仪(FTIR)、X射线衍射仪(XRD)和扫描电子显微镜(SEM)等方法表征了复合材料的结构,采用示差量热扫描仪(DSC)和储放热实验考察了复合材料的储/放性能和稳定性。结果表明采用热熔法和溶液浸渍法制备的材料具有相同的结构,硬脂酸按38.5%的负载率以物理作用吸附于活化凹凸棒石表面,其相应的相变焓分别为68.44 J/g和69.06 J/g。稳定性实验表明2种材料均具有良好的化学稳定性,但热稳定性存在差异,热熔法制备的复合材料的热稳定性优于浸渍法制备的复合材料。     

纳米胶囊相变材料的制备

采用超声波工艺及细乳液原位聚合方法,研制了以聚苯乙烯为囊壁、正十八烷为囊芯的纳米胶囊相变材料;系统探讨了聚合反应各因素对乳胶粒子的形态、胶囊材料热性能的影响。适宜的反应条件为：引发剂AIBN 0.5%（油相质量分数,下同）;链转移剂DDT 0.4%;正十八烷与苯乙烯比为1∶1以及复合乳化剂（SDS和OP-10）总量2%,配比为1∶1。实验结果表明胶囊Z均直径124 nm,相变焓可达124.4 kJ·kg-1。     

固-固相变储热材料的研究进展

与固-液相变材料相比,固-固相变材料（SS-PCMs）受到的关注较少;鉴于SS-PCMs具有储能密度高、无毒且腐蚀性小、相变时无液体产生且体积变化较小、不易发生相分离以及过冷度小等优点,因而是一类具有发展潜力的相变材料。本文基于SS-PCMs的研究现状,对近年来几类重要SS-PCMs如多元醇SS-PCMs、高分子类SS-PCMs及无机盐类SS-PCMs的研究进展进行了综述。简要阐述了SS-PCMs的分类以及各类SS-PCMs的性能、相变储热机制和优缺点。同时介绍了选择固-固相变材料应用时的基本原则,并针对相变材料热导率低,过冷度大、稳定性差等问题的改性研究进行了综述,还简要综述了SS-PCMs的应用研究。最后指出,未来的研究应着眼于解决已合成SS-PCMs的缺陷,开发多功能的SS-PCMs,并在SS-PCMs的实际应用方面实现突破。     

原位聚合法研制纳米胶囊相变材料

采用超声波工艺及细乳液原位聚合方法,研制了以聚苯乙烯为囊壁、正十八烷为囊芯的纳米胶囊相变材料;系统探讨了聚合反应各因素如引发剂、链转移剂、表面活性剂以及正十八烷/苯乙烯比等对乳胶粒子的形态、胶囊材料热性能的影响,对所研制的胶囊相变材料进行激光衍射粒度分析、透射电镜及差示扫描量热等表征.实验结果表明,在引发剂AIBN 0.5%(油相质量百分比,下同);链转移荆DD在T0.4%;复合乳化剂(SDS/OP10)总量2%,配比1:1及正十八烷/苯乙烯比=1:1条件下,胶囊呈球形均匀分布,聚苯乙烯囊壁能将正十八烷囊芯很好包裹住,其胶囊Z均直径124nm,相变焓可达124.4kJ·kg-1.     

聚双甲基丙烯酸聚乙二醇酯固-固相变储能材料的制备

制备了以聚甲基丙烯酸为骨架、聚乙二醇(PEG)为工作物质的新型高分子固-固相变储能材料。对PEG和几种不同的相变材料分别进行DSC测试,对PEG分子量为4000的相变材料进行非等温DSC测试。结果表明,与纯PEG相比,相变材料的相转变温度降低12.3℃,相变焓降低45 J/g。随着聚乙二醇分子量由2000依次增加为4000,6000,10000,相变材料的相转变温度分别为44.8,52.9,63.8和74.3℃,相变焓分别为142.9,203.2,190.1,231.4 J/g,均有增加的趋势。随着升温速率增加,PEG分子量为4000的PCM的相变温度依次升高,分别为47.4,50.0和53.1℃。     

光固定形的十八烷相变材料制备及热性质研究

该文以新戊二醇二甲基丙烯酸酯（Neopentyl glycol dimethacrylate,NPGDMA）为单体,利用光固化反应制得具有3D网络结构的聚合物 ,这种结构可以有效包裹十八烷（n-octadecane,ODE）,从而解决十八烷的泄漏问题。用高导热氮化硼（BN）作为导热填料,成功制备了一种导热性良好并且形状稳定的ODE/NPGDMA/BN复合相变材料。当ODE和NPGDMA的质量比为1:1时,具有较低的泄露率和较大的潜热。因此,选择ODE含量为50%的配方进行后续实验。通过FTIR、XRD、SEM和EDS对材料的结构、形貌和元素分布状态进行了表征。通过热台测试表明制备的复合相变材料在高于ODE的相变温度（28 ℃）时,没有发生形状变化,说明具有较好的形状稳定性;通过TGA测试可以看出在100 ℃之前没有发生重量损失,说明复合相变材料具有较好的热稳定性;通过DSC测试说明ODE/NPGDMA/BN复合相变材料具有较大的潜热 （103.9 J/g）。复合材料中BN的添加量为5%时,其导热率比纯ODE增加约49.6%     

窄粒径分布的液体石蜡相变微胶囊制备及性能表征

目前相变微胶囊的制备普遍采用传统的机械搅拌乳化方法,获得微胶囊的粒径大小难以控制,粒径分布范围较大。本工作采用快速膜乳化技术结合原位聚合法获得窄粒径分布的液体石蜡/密胺树脂相变微胶囊。研究发现,过膜压力和过膜次数对相变微胶囊的粒径大小和分布影响较大,当微孔玻璃膜孔径固定时,调节过膜压力和过膜次数可以控制微胶囊的粒径大小和分布。当使用孔径为10.1 μm的微孔玻璃膜时,采用过膜压力为0.2 MPa、过膜次数为4次时,可以获得粒径分布最窄的液体石蜡相变微胶囊。此时微胶囊的平均粒径为10.84 μm,相对标准偏差仅为0.16,远小于机械搅拌乳化制备的微胶囊的粒径相对标准偏差。且微胶囊表面光滑致密,无明显团聚,具有良好的耐热性能和冷/热循环稳定性,微胶囊包裹率约为80%。此外,快速膜乳化技术的引入大大提高了乳化效率,从而显著提高了微胶囊制备效率,对其他窄粒径分布的低温烷烃相变微胶囊的批量化制备具有重要意义。