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1.
采用原位聚合法用三聚氰胺-甲醛树脂包覆正十八烷,制备出相变微胶囊.利用扫描电镜和差示扫描量热仪对微胶囊试样的表面形貌和热物理性能进行了研究.实验结果表明:制备的相变微胶囊表面光滑,平均粒径2.84μm,平均壁厚0.41μm.  相似文献   

2.
以石墨烯/正十八烷为芯材,三聚氰胺-尿素-甲醛树脂(MUF)为壁材,苯乙烯马来酸酐共聚物(SMA)为乳化剂,采用乳液聚合法制备相变微胶囊.系统研究了石墨烯对于正十八烷微胶囊性能的影响.采用场发射扫描电子显微镜(FE-SEM)、傅里叶变换红外光谱分析仪(FTIR)、拉曼光谱仪、X射线衍射仪(XRD)、Hot Disk热常数分析仪、示差扫描量热仪(DSC)和热重分析仪(TGA)对相变微胶囊的外貌形态、晶型结构和热性能进行表征和分析.结果表明,微胶囊呈圆球形且光滑,粒径约为1~30μm.当石墨烯添加量为0.1 g时,微胶囊的形貌无明显变化.当加入过量石墨烯时,微胶囊出现了明显的团聚现象.XRD测试表明,包覆于微胶囊中的石墨烯没有使微胶囊的结晶峰位置发生明显的偏移,这对于微胶囊的实际应用是有利的.微胶囊的相变热焓和包覆率随着石墨烯的加入而不断减小,但芯材的过冷现象得到了明显的改善.石墨烯对于微胶囊传热性能的提升有着显著的效果.当石墨烯的添加量为0.2 g时,微胶囊的导热系数为0.092 W·m-1·K-1,与纯微胶囊相比提高了约51%,这说明石墨烯改善了传统相变微胶囊的传热性能,提升了相变微胶囊的应用性能.  相似文献   

3.
利用界面聚合法,以异佛尔酮二异氰酸酯与己二胺为单体聚合形成的聚脲为外壳,以正十八烷、薄荷素油的混合物为芯材,制备了具有薄荷香味的相变微胶囊。利用光学显微镜、扫描电镜、红外光谱仪、差示扫描量热仪、热重分析仪等对微胶囊的形貌、化学结构和热性能进行了表征。结果表明:制备的微胶囊为球形,平均粒径约7.0μm,有较高的储热能力和较好的热稳定性;芯材中添加8.3%的正十四醇或高熔点石蜡,可很好地抑制相变微胶囊的过冷现象。  相似文献   

4.
丙烯酸共聚物囊壁的正十八烷微胶囊的制备和性能表征   总被引:1,自引:0,他引:1  
以二丙烯酸1,4-丁二醇酯为交联剂, 成功制备了甲基丙烯酸甲酯-甲基丙烯酸共聚物为壁材, 正十八烷为囊芯的相变材料微胶囊. 采用扫描电子显微镜(SEM)、差示扫描量热仪(DSC)和热重分析仪(TG)分别考察了单体与芯材投料比、单体浓度和交联剂的含量对微胶囊形貌、相变热性能、热稳定性能的影响. 实验结果表明: 随着单体与芯材投料比或单体浓度的增加, 微胶囊表面均变得致密, 壁厚增加; 随着交联剂含量的增加, 微胶囊的表面变得更加致密光滑, 热稳定性显著增强; 随着单体与芯材投料比的增大, 微胶囊热焓值减小, 被包裹的囊芯含量减少.  相似文献   

5.
采用乳液聚合的方法,分别选取聚苯乙烯(PS)、聚甲基丙烯酸甲酯(PMMA)或苯乙烯和甲基丙烯酸甲酯的共聚物为壁材,正十八烷为芯材,十二烷基苯磺酸钠(SDBS)为乳化剂,制作相变储能微胶囊。用粒径分析仪、透射电子显微镜(TEM)、热重分析仪(TG)和示差扫描量热测试仪(DSC)对微胶囊的形貌、相变热性能和热稳定性分别进行表征。结果表明:壁材选取两者共聚物,当两种单体的比例为St∶MMA=1∶5,SDBS用量为1.5g(总质量的3%)时,微胶囊粒径大小均匀,粒子分散性好,壁材的包裹性好。微胶囊的放热峰为起始温度为27.3℃,终止温度为31.9℃,相变温度为28.9℃,相变焓为48.4J/g。TG表明长期使用温度不能超过131℃。IR分析微胶囊中含有芯材和壁材。这种十八烷/聚(St-MMA)相变微胶囊可以用于诸能材料。  相似文献   

6.
界面聚合法制备正二十烷微胶囊化相变储热材料   总被引:1,自引:0,他引:1  
用界面聚合的方法,以甲苯-2,4-二异氰酸酯(TDI)和己二胺(HDA)为反应单体,非离子表面活性剂聚乙二醇壬基苯基醚(OP)为乳化剂,合成了正二十烷为相变材料的聚脲包覆微胶囊. 结果表明,二异氰酸酯和己二胺按质量比为1.5∶ 0.8进行反应. 空心微胶囊的直径约为0.2 μm,含正二十烷微胶囊直径为2~6 μm. 红外光谱分析证明, 囊壁聚脲是由TDI及HDA 2种单体形成. 正二十烷包裹效率为65%~80%. 微胶囊的熔点接近囊芯正二十烷的熔点,而其储热量在壁材固定时随囊芯的量而变. 热重分析结果表明,囊芯正二十烷、含正二十烷的微胶囊以及壁材聚脲,能够耐受的温度分别约为130、165及250 ℃.  相似文献   

7.
界面聚合法制备正二十烷微胶囊化相变储热材料   总被引:5,自引:0,他引:5  
采用界面聚合的方法, 以甲苯鄄2,4-二异氰酸酯(TDI)和乙二胺(EDA)为反应单体, 非离子表面活性剂聚乙二醇壬基苯基醚(OP)为乳化剂, 合成了正二十烷为相变材料的聚脲包覆微胶囊. 结果表明, 二异氰酸酯和乙二胺按质量比1.9:1 进行反应. 以透射电镜和激光粒度分析仪分析微胶囊, 测得空心微胶囊直径约为0.2 μm, 含正二十烷微胶囊约为2-6 μm. 红外光谱分析证明, 壁材料聚脲是由TDI 及EDA 两种单体形成的. 正二十烷的包裹效率约为75%. 微胶囊的熔点接近囊芯二十烷的熔点, 而其储热量在壁材固定时随囊芯的量而变. 热重分析表明, 囊芯正二十烷、含正二十烷的微胶囊以及壁材料聚脲, 能够耐受的温度分别约为130 ℃、170 ℃及270 ℃.  相似文献   

8.
正十六烷聚脲微胶囊化相变材料   总被引:17,自引:0,他引:17  
用界面聚合法,合成了直径大约2.5 μm可用于热能储存含相变材料的聚脲包覆微胶囊.在含乳化剂的水溶液中,将溶有芯材正十六烷的有机相乳化成微米级油性液滴,随后加入的水溶性单体二胺与甲苯2,4-二异氰酸酯在胶束界面相互反应形成囊壁.分别用乙烯二胺,1,6-己二胺和它们的混合物作为水溶性单体进行了研究.并用红外光谱和热分析分别考察了不同胺类对微胶囊化学结构和热性质的影响.红外谱图显示合成了聚脲微胶囊,热重曲线表明含正十六烷的聚脲微胶囊能够耐受大约300 ℃高温,差示扫描量热测试表明所有样品均具有合适的相转变热,冷热循环实验揭示微胶囊能够维持储热容量不衰减.研究表明微胶囊化的正十六烷作为相变储热材料具有良好的应用前景.  相似文献   

9.
本文研究了醇类(正丁醇、正戊醇、正辛醇和正癸醇)、油类(正十八烷、正十六烷、正十四烷、正十烷、正癸烷和正辛烷)、正十八烷含量以及NaCl浓度对Tween80/醇/油/水体系相图的影响。结果表明,NaCl浓度对Tween80/正辛醇/正十八烷/水体系相图的影响不明显;醇类随着炭原子数目的增加,O/W微乳液区面积增大,W/O微乳液区面积减小,微乳液区总面积增大;不同的油类形成的微乳液区面积由大到小的顺序是:正十六烷≈正十四烷>正十二烷>正癸烷>正十八烷>正辛烷;随着正十八烷含量的增加,微乳区面积减小。用2277热活性检测系统测定了石油菌B-2分别在非微乳液和助表面活性剂分别是正戊醇、正辛醇,油是正十八烷所形成的微乳液中生长的功率-时间曲线。结果表明微乳液培养基更适用于B-2利用高碳烷烃进行生长;正辛醇作助表面活性剂形成的微乳液培养基比正戊醇作助表面活性剂形成的微乳液培养更为有利;O/W型微乳液比W/O型微乳液对B-2的生长更为有利。  相似文献   

10.
以十八烷/聚(苯乙烯-甲基丙烯酸甲酯)(P(St-MMA))微胶囊为相变材料,硅橡胶作为载体,制备了十八烷/P(St-MMA)/硅橡胶复合材料。研究了微胶囊的加入方式及加入量,硅橡胶包覆方法。通过红外光谱(IR)和扫描电镜(SEM)研究复合材料的结构和形貌。通过力学性能测试如拉伸强度、扯断伸长率,确定最佳的加工方法。通过热重分析法(TG)、差示扫描量热法(DSC)和储热性能对复合材料的热性能进行研究。结果表明,十八烷制成微胶囊加入到硅橡胶中,且微胶囊加入量是2份时,十八烷/P(St-MMA)微胶囊/硅橡胶的热稳定性热稳定性及力学性能较好。室温硅橡胶包覆微胶囊掺混固化法制备的复合材料的力学性能优于直接共混后热固化法和混炼涂抹后热固化法。十八烷/P(MMA-St)/硅橡胶复合材料的焓值为67.6J/g,储能效果好。  相似文献   

11.
甲基丙烯酸N,N-二甲氨基乙酯的均聚物(PDMAEMA)在水中的溶解性具有温敏性,即低温溶解、高温不溶,而且其低临界溶液温度(LCST)与pH密切相关.本文重点考察了PDMAEMA水溶液在不同温度、pH值、溶液离子强度时的相转变特性,并研究了水溶液中乳化剂对PDMAEMA的疏水相互作用和增溶稳定作用.将PDMAEMA的温敏相转变行为同有关乳液的稳定性相关联,揭示了改善乳液稳定性的内在机制.  相似文献   

12.
三聚氰胺-甲醛树脂包裹环氧树脂微胶囊的制备及表征   总被引:4,自引:0,他引:4  
针对环氧树脂基材料的自修复,选取四氢邻苯二甲酸二缩水甘油酯作为芯材,采用三聚氰胺-甲醛树脂为壁材,对其进行微胶囊化包裹.结果表明,制得的具有单囊结构的环氧树脂微胶囊,胶囊粒径较小(约6.7μm)、囊壁较薄(约0.2μm)、芯含量较高(83.2 wt%),囊壁内、外表面光滑致密,胶囊具有良好的密闭性和耐热性;在微胶囊化过程中,三聚氰胺-甲醛树脂的缩聚反应动力学起关键作用,芯材没有参与囊壁形成的交联反应;包裹后的芯材活性保持不变,胶囊被复合到材料过程中囊芯活性也保持不变;胶囊的强度较高,能承受与基体材料复合过程中的外力作用,且与基体材料间粘结良好,在裂纹形成过程中能够随基体同时开裂.  相似文献   

13.
The influence of the molecular weight of sodium salt of styrene/methacrylic acid (SSMA) copolymers and solution pH value (range of 3–11) on the stability of the atrazine suspension was studied. SSMA with different molecular weights was synthesized by emulsion polymerization. Adsorption, zeta potential measurements, microscopy, and suspension stability measurements were carried out. The obtained results indicate that the adsorption of SSMA on the surfaces of atrazine particles decreases with the increase of the molecular weight, and the hydrogen bonding is the main adsorption force. The presence of SSMA improves the stability of the atrazine suspension. The stability of the atrazine suspension decreases with the increase of the molecular weight of SSMA. On the other hand, the stability of the atrazine suspension with SSMA increases firstly and then decreases with the increase in solution pH in the range of 3–11.  相似文献   

14.
A novel propisochlor microcapsules suspension (CS) was prepared via in-situ polymerization. The preparation of melamine-formaldehyde resin microcapsules containing propisochlor with different ratios of core-shell material was investigated. The synthesized microcapsules were characterized by Fourier Transform Infrared spectrometer, Scanning Electron Microscope, Ultraviolet spectrometry, Thermogravimetric analyses and particle size analyzer. As the ratio of core/shell was 1, the diameter of the prepared microcapsules was the smallest (3.55?µm), while narrowest size distribution (span: 1.19) and the melamine formaldehyde microcapsules possessed the highest encapsulation efficiency (93.26%). The surface of the microcapsules was smooth and the microcapsules had poor adhesion. These microcapsules had compact microstructures and global shapes, which had a good thermal stability and propisochlor could be preserved better in the poly(melamine-formaldehyde) (PMF) microcapsules. These results indicated that the prepared microcapsule had better performance. Additionally, the propisochlor was easily degraded through microorganisms and had a short half-life. The microcapsule suspension of propisochlor hasn’t been researched yet. Therefore, it is significant to prepare microcapsule suspension. The technology of controlled release has effectively prolonged the persistence of active ingredients. More importantly, there is no use of organic solvents in the preparation of microcapsules suspension, which avoided the pollution of solvents to the ecological environment.  相似文献   

15.
Novel monodisperse cationic pH-responsive microcapsules are successfully prepared using oil-in-water-in-oil double emulsions as templates by a microfluidic technique in this study. With the use of a double photo-initiation system and the adjustment of pH value of the monomer solution, cross-linked poly(N,N-dimethylaminoethyl methacrylate) (PDM) microcapsules with good sphericity and monodispersity can be effectively fabricated. The obtained microcapsule membranes swell at low pH due to the protonation of N(CH(3))(2) groups in the cross-linked PDM networks. The effects of various preparation parameters, such as pH of the aqueous monomer fluid, concentration of cross-linker, concentration of monomer N,N-dimethylaminoethyl methacrylate (DM) and addition of copolymeric monomer acrylamide (AAm), on the pH-responsive swelling characteristics of PDM microcapsules are systematically studied. The results show that, when the PDM microcapsules are prepared at high pH and with low cross-linking density and low DM monomer concentration, they exhibit high pH-responsive swelling ratios. The addition of AAm in the preparation decreases the swelling ratios of PDM microcapsules. The external temperature has hardly any influence on the swelling ratios of PDM microcapsules when the external pH is less than 7.4. The prepared PDM microcapsules with both biocompatibility and cationic pH-responsive properties are of great potential as drug delivery carriers for tumor therapy. Moreover, the fabrication methodology and results in this study provide valuable guidance for preparation of core-shell microcapsules via free radical polymerization based on synergistic effects of interfacial initiation and initiation in a confined space.  相似文献   

16.
UV光引发的丙烯酰胺反相乳液聚合   总被引:7,自引:0,他引:7  
报道了不透明丙烯酰胺反相乳液体系的UV光引发聚合新方法 .使用普通中压汞灯并辅以适当搅拌 ,UV光引发丙烯酰胺 水 煤油 Span80 +OP 10反相乳液聚合可在 2 0min左右完成 ,所得聚合物分子量达千万 ;聚合过程中不存在恒速期 ,扫描电镜未观察到聚合前后乳胶粒径有数量级的变化 ,表明聚合反应以单体液滴成核为主 .此外 ,考察了光引发剂类型及浓度、单体浓度、乳化剂用量、反应温度等对聚合反应的影响 ,结果表明不同光引发剂的引发活性为Irgacure 2 95 9>(ITX +EDAB) >BDK ,引发剂浓度增加 ,反应速度先增加而后降低 ,存在一最大值 ;单体浓度增加 ,反应速度加快 ,聚合物分子量提高 ;乳化剂用量增加 ,反应速度加快而分子量变化不明显 ;聚合表观活化能为 13 34kJ mol.  相似文献   

17.
Microcapsules containing PRS® paraffin wax (core) and a polystyrene shell were prepared by suspension-like polymerization. The influence of reaction temperature, stirring rate, and mass ratio of paraffin wax to styrene on the properties of phase change materials microcapsules was studied. The reaction temperature had not a significant effect on the size of the microcapsules but an increase of molecular weight and a narrow molecular weight distribution of polystyrene shell were observed when reaction temperature was increased. An exponential relationship between the stirring rate and the mean particle diameter in number has been found. It was observed that paraffin is difficultly encapsulated when the paraffin/polymer mass ratio was higher than 2.00, as a consequence of a shortage of polymer that could not completely cover the amount of paraffin added. However, when a large proportion of monomer was employed, the polymer tended to polymerize inside the droplets during the microencapsulation process forming complex inner structures. The microcapsules obtained have an interesting energy storage capacity of 153.5 J/g that makes them suitable for different applications.  相似文献   

18.
Microcapsules containing n-octadecane were successfully fabricated by an in-situ polymerization process with melamine-formaldehyde (MF) prepolymer and a hydrolyzed copolymer of styrene and maleic anhydride (SMA) as shell materials. To achieve a long service time of microcapsules containing phase change materials (microPCMs), the compactness of shells was improved by adding the MF prepolymer twice. The mechanism of this method was a two-step coacervation (TSC) under the help of hydrolyzed SMA compared to a one-step coacervation (OSC). To understand the influence of both coacervations, properties of shells were investigated in terms of morphologies, density, thickness, and stability by means of scanning electron microscopy (SEM), transmission electron microscopy, and thermal gravimetric analysis (TGA). The data of shells thickness were achieved from the cross-section SEM images. It shows that the average thickness of shells from two kinds of process are 0.1 μm. The density and stability in water of shells fabricated by TSC are both higher than that of shells by OSC. TGA curves show the expected microPCMs of TSC losing weight from 200 to 400 °C. The release curves, relationship between time and logarithmic residual weight of core, show there are two decrease-linear steps after curve regression. It can be concluded from all these results that the TSC method may be a promising method leading to a compact shell structure for various application.  相似文献   

19.
Droplet-based microfluidic technology can be utilized as a microreactor to prepare novel functional monodisperse microcapsules. In this study, a droplet-based microfluidic chip with surface modification,which allowed the one-step preparation of double emulsion microcapsules. An O/W/O double emulsion using polyethylene(glycol) diacrylate(PEGDA) solution as the intermediate water phase was prepared by regulating the hydrophilicity and hydrophobicity of the chip surface, with PEGDA microcapsules pr...  相似文献   

20.
黄鹤  李建法 《合成化学》1993,1(2):155-163
采用复合乳液聚合技术,合成了环氧树脂/聚(丙烯酸丁酯—苯乙烯—甲基丙烯酸甲酯)[EP/P(BA—St—MMA)]半胶乳型互穿聚合物网络(semi—LIPN),并探讨了反应温度、乳化剂用量、引发剂用量、不同单体配比、体系 pH 值、搅拌速度、EP 含量、交联剂种类及用量对聚合反应转化率及聚合稳定性的影响。  相似文献   

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