油井用相变微胶囊的制备与性能

针对深水固井作业过程中水泥水化放热较大,易致使环空地层天然气水合物分解的技术难题,本文以石蜡为芯材,碳酸钡为壁材,制备了一种油井用相变微胶囊。首先,利用FT-IR、DSC、TGA与SEM对相变微胶囊的化学组成、热性能与微观形貌进行了表征。结果表明：相变微胶囊的封装效率为67.40%,具有较高的封装效率和良好的潜热储存能力。其次,对粒径分布与润湿性能进行了测试。结果表明：微胶囊颗粒平均粒径为4.946 μm,小于水泥颗粒粒径17.201 μm,可较好的镶嵌在水泥石中,并充填于水泥水化产物之间,减小对水泥石力学性能的负面影响;微胶囊与水的静态接触角为46.8°,具有良好的亲水性能,可应用于水基的水泥浆环境中。最后,将微胶囊应用于水泥浆体系,研究了水泥浆的水化温升和水化热。结果表明：与空白水泥浆相比,加入12%相变微胶囊水泥浆的最高水化温升与水化热（48 h）分别下降了14.56%和43.23%。      

细粒径石蜡微胶囊相变材料的制备与性能

采用阳离子和非离子复配乳化剂,通过原位聚合制备以丙烯酸酯为壁材,石蜡为芯材的细粒径微胶囊相变材料.采用傅里叶变换红外光谱(FTIR)、扫描电子显微镜(SEM)、差示扫描量热(DSC)、热重(TG)及激光粒度仪分析表征了微胶囊相变材料的化学结构、表面形貌和热性能.结果表明,乳化剂的种类和壁材单体的配比对微胶囊性能有重要的影响.当采用阳离子和非离子复配乳化剂,壁材中单体甲基丙烯酸甲酯(MMA)与丙烯酸(AA)的质量比为9∶1时,微胶囊相变材料呈球形且表面光滑紧凑,尺寸仅为0.2~0.35μm,具有良好的储热能力,相变潜热高达169 J/g;微胶囊中壁材对石蜡芯材的分解具有明显热阻滞作用,分解温度比纯石蜡提高了150℃.     

蓄热调温石蜡相变微胶囊的制备及性能

采用界面聚合法,以甲苯2,4-二异氰酸酯和哌嗪为反应单体、30号相变石蜡为芯材,制得了一种智能纺织品用蓄热调温相变微胶囊。通过红外光谱、扫描电镜、差示扫描量热仪对微胶囊的化学组成、形貌和蓄热性能进行了表征,测试了其耐热和耐溶剂性。结果表明:所得微胶囊主要为球形,表面光滑,平均粒径为10.6μm,对w=0.40的NaOH溶液、w=0.60的H2SO4溶液、无水乙醇、丙酮稳定,能被甲苯、二甲基甲酰胺、乙醚破坏。相变潜热为118 J/g,石蜡在微胶囊中的质量分数为84%。     

石墨烯/正十八烷微胶囊的制备与及其热性能研究

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.     

十八烷/聚(St-MMA)相变微胶囊制备及表征

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。     

单分散聚合物微球稳定Pickering乳液法制备大粒径微胶囊相变材料

采用二步加料的分散聚合法制备单分散聚甲基丙烯酸缩水甘油酯(PGMA)微球, 并使其水解, 得到水包油(O/W)型Pickering乳液稳定剂. 在Pickering乳液聚合过程中, 利用相分离机制, 形成了聚苯乙烯(PSt)和 PGMA复合为整体囊壳的微胶囊相变材料. 微胶囊平均粒径达76 μm, 囊芯含量高达83%, 相变焓达到174 J/g, 具有很高的储热容量.     

相变调温微胶囊的制备

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．     

高效氯氰菊酯微胶囊的制备、表征及释放性能

以高效氯氰菊酯为芯材, 乙基纤维素为壁材, 采用溶剂蒸发法制备了微胶囊, 并对其理化性能进行表征, 通过单因素实验研究了工艺参数对微胶囊外观形貌、 粒径大小及分布、 包封率、 载药量和缓释性能的影响. 结果表明, 乳化剂种类和剪切时间可以显著影响微胶囊的外观形貌; 随着乳化剂用量增大, 微胶囊粒径减小, 分布变窄, 当Tween-80用量从4%增加至8%时, 微胶囊平均粒径从59.9 μm减少到29.8 μm, 跨距也从1.21减少到0.72. 随着芯壁比(质量比)减小, 微胶囊粒径和包封率均逐渐增大, 载药量逐渐减小, 当芯壁比为1:1.75时, 包封率可以达到70%以上. 微胶囊释放动力学模型符合Ritger-Peppas模型(lgQ=lgk+nlgt); 平均粒径相近而载药量不同时, 初期载药量最小的样品释放速率慢, 累积释放率低; 载药量相近而平均粒径不同时, 粒径大的样品释放速率低, 累积释放率也低.     

潜伏性热释放型微胶囊固化剂2苯基咪唑-聚甲基丙烯酸缩水甘油酯的结构表征与性能研究

以2-苯基咪唑(2PZ)为芯材,聚甲基丙烯酸缩水甘油酯(PGMA)为壁材,采用溶剂挥发技术,成功地制备了一种新型潜伏性热释放型微胶囊固化剂2PZ-PGMA。通过FT-IR、TGA、SEM、粒度分析和DSC对微胶囊固化剂的化学结构、芯材含量、表面形貌、粒径分布及固化性能等进行了表征。所制备的微胶囊固化剂表面光滑,粒径分布较窄,平均粒径为约17.6μm,壁材厚度为约1.1μm,芯材2PZ含量为20.1(wt)%。由微胶囊固化剂与环氧树脂E-51制备的单组分胶粘剂,具有优良的固化特性、潜伏性能和粘接性能,可在100℃下30min内实现固化,室温储存期达33d以上,拉伸剪切强度达15.36MPa。     

分散共聚法制备窄分布P(St-co-nBA)微球

用分散共聚法制得窄分布苯乙烯(St)和丙烯酸正丁酯(nBA)的共聚物微球.采用1H-NMR、DSC、FTIR、SEM、LS等对共聚物的结构、形态、性能进行表征,考察了初始单体配比、温度、稳定剂浓度、分散介质极性、引发剂对微球粒径、粒径分布及转化率的影响.实验结果表明,初始单体比nBA/St增大,微球粒径增大,分布变宽,...     

热敏显色微胶囊的制备与表征

热敏显色微胶囊是用于传真、条形码系统、医用图像、各种打印等领域的重要材料,它是一种内部含有染料隐色体的球形胶囊。染料隐色体是一种内酯结构的无色染料,在一定条件下,与显色剂发生显色反应。由于染料隐色体的化学惰性不够理想,易受外界因素的干扰,因而在应用中受到一定限制,所以为了克服其存在的不足,常将其微胶囊化。微胶囊的芯壁结构可以将芯材与外界隔离,提高芯材的稳定性,同时保留芯材原有的化学性质。当环境温度在微胶囊的玻璃化温度以上时,由于形成微胶囊壁的物质透过性显著增加,因此显色成分接触而发生显色反应。本文利用界面聚合法,以聚乙烯醇为保护胶体,曲拉通X-100为表面活性剂,聚氨酯为壁材,染料隐色体为芯材,合成了聚氨酯热敏显色微胶囊。研究了三个主要因素对微胶囊的粒径及其分布、表面形貌和热敏显色性能的影响。结果表明,增大保护胶体浓度,提高乳化速度,增加乳化剂用量,微胶囊的平均粒径变小,粒径分布变窄,表面变得光滑而且致密,具有较高的热敏显色密度。利用红外光谱仪确认了微胶囊的结构,在最优条件下,所制备的微胶囊玻璃化温度为131 ℃,并具有良好的热稳定性。     

Release behaviors of porous poly(butylene succinate)/poly(epsilon-caprolactone) microcapsules containing indomethacin

The biodegradable poly(butylene succinate)/poly(epsilon-caprolactone) (PBS/PCL) microcapsules containing indomethacin were prepared by emulsion solvent evaporation method. The morphologies, thermal properties, and release behaviors of PBS/PCL microcapsules were investigated. As a result, the microcapsules exhibited porous and spherical form in the presence of gelatin as a surfactant. From the DSC result, the PBS/PCL microcapsules showed the two exothermic peaks meaning the melting points of PCL and PBS. The results of FT-IR and DSC proved that the PBS and PCL were mixed so that the PBS/PCL microcapsules were composed of two wall-forming materials. And the release rate of indomethacin from the microcapsules was decreased with increasing the PCL content. It was noted that an addition of PCL on the PBS led to the decrease of pore size in the PBS/PCL microcapsules.     

Microencapsulation of capsaicin by solvent evaporation method and thermal stability study of microcapsules

With polylactic acid (PLA) as shell and capsaicin as core substances, microcapsules were prepared based on solvent evaporation method. The orthogonal test was used to analyze the effects of the process conditions such as polyvinyl alcohol and PLA concentrations, stirring rate, and oil/water ratio on the particle size of the microencapsulated capsaicin (MC) agents. The chemical composition, morphology and size distribution of the microcapsules prepared by the most satisfactory conditions were analyzed by Fourier transform infrared spectroscopy, laser light scattering, and scanning electron microscopy. The MC agents had a mean diameter of 3–5 μm. The thermal properties of the MC agents were measured by differential scanning calorimetry and thermogravimetric analysis, it was demonstrated that the thermal stability of the MC agents was changed or even improved by the encapsulated PLA over the surface, when compared with similar parameters of the uncovered capsaicin. The in vitro release profile suggested that the microcapsules could be a suitable material for controlled release of capsaicin.     

Preparation and characterization of poly(melamine-formaldehyde) microcapsules filled with propisochlor

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.     

Preparation and properties of chitosan chondroitin sulfate complex microcapsules

The chitosan (CHS) chondroitin sulfate (CS) complex microcapsules were prepared by emulsion-chemical crosslink method, with the chitosan and chondroitin sulfate as the wall materials and the low molecular weight heparin (LMWH) as the core materials. The microcapsules were characterized by Fourier transform infrared (IR) spectrometry, scanning electron microscope (SEM), size distribution and thermal analysis. The in vitro drug release behavior of the microcapsules was studied by spectrophotometry. The SEM and size distribution showed that the microcapsules were in the spherical form mostly in the size range of 20-80 microm. The IR spectrum indicated that there were electrostatic interactions between chitosan and chondroitin sulfate, with the sulfate group and free carboxyl group reacted with the amino groups of chitosan. The DSC result showed that the wall materials could protect the core materials of the microcapsules. The results of the release kinetics experiments of the microcapsules showed that the drug released slightly faster in acid media than in alkali ones.     

胆甾相液晶微胶囊制备与表征

为了实现液晶的分散、保护和致稳,完成了DYE液晶的包覆。对该方法所采用的芯壁比、乳化剂含量、剪切速度和剪切时间等影响微胶囊包覆因素做了研究。首先,用自由基聚合法制备了液晶微胶囊。接着,以偏光显微镜(POM)检验液晶微胶囊的包覆效果,即在液晶微胶囊经过加热前后,液晶是否仍然保持其独有的光学特性。然后,在分析比较SEM和激光粒度仪等评价方法的性能的基础上,说明了液晶微胶囊的形貌及粒径分布。最后,利用傅里叶变换红外光谱仪再次验证了液晶微胶囊的包覆效果。实验结果表明：当芯壁比为5:4时,剪切速度为7000 rpm,剪切时间为10 min,乳化剂HSMA含量为5 ml时,微胶囊的形貌及粒径分布最优,液晶微胶囊显色性能最优。研制的DYE液晶微胶囊具有单分散性好、显色性优、耐高温能力强等优点,并以此微胶囊制备了热至变色液晶膜。     

二氧化钛膜参数对离子液体基染料敏化纳米薄膜太阳电池性能的影响

Photo correlation spectroscopy was used to measure the particle size distribution of TiO2 films. Other parameters, such as porosity, BET surface area, average pore size, crystallite size D101, distribution of pore size etc. were also measured. The effects of these parameters on the ionic liquid based dye-sensitized solar cells （DSC） were studied. It was concluded that the particle size distribution of nanocrystalline TiO2 played an important role on the performance of DSC. The narrow particle size distribution of nanocrystalline TiO2 increased the efficiency of DSC, while the wide distribution decreased the efficiency of DSC. From the result above, it was also concluded that the photo correlation spectroscopy was a good method to identify the performance of TiO2 films. Based on electrochemical impedance spectroscopy, we found that the particle size distribution could affect the electronic contact between the TiO2 layers as well. The narrow particle size distribution made the electronic contact between TiO2 layers better than the wide particle size distribution of the TiO2 films, and then better the electronic contact, higher the efficiency of the DSC.     

Optimization of parameters in preparation of PCM microcapsules based on melamine formaldehyde through dispersion polymerization

Microencapsulated phase change materials have attracted special attention due to their wide applications in saving and releasing energy. Here, microencapsulation of hexadecane (HD) in melamine formaldehyde shell was carried out through in situ dispersion polymerization in the aqueous media. Some important parameters such as stabilizer type and amount, surfactant amount, homogenization conditions as the critical affective factors on final particle size, morphology, and thermal resistance of the microcapsules were investigated extensively. The obtained microcapsules were concurrently analyzed by SEM, differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) techniques. SEM images showed that the best stabilization was achieved by polyvinyl alcohol. Also, particle size, as an indication of surface area for heat transfer properties, showed a decrement by increasing stabilizer amount, surfactant amount, and homogenization speed. The amount of entrapped HD and efficiencies of microencapsulation were determined by DSC, and the reason for observing such changes were discussed in detail. Thermal stability of the microcapsules as an important property for their performance was investigated, too. The results illustrated that an improved thermal stability would be obtained by an efficient stabilization in the emulsification step. Also the highest thermal stability up to 388 °C was reached at homogenization speed of 6,000 rpm. Finally, the optimized conditions for desirable encapsulation were proposed in such systems.