三聚氰胺-脲素-甲醛@石蜡微胶囊相变材料的制备及其性能研究

采用石蜡为芯材,三聚氰胺-脲素-甲醛树脂为壁材,利用原位聚合法制备相变储能材料,研究了氧化石墨烯、十二烷基硫酸钠、司盘80、吐温80作为石蜡乳化剂对合成微胶囊相变材料(MicroPCMs)化学结构、粒径分布、热性能和微观形貌的影响.结果表明,三聚氰胺-脲素-甲醛树脂壁材可对石蜡芯材进行有效包覆,形成微胶囊结构的复合相变...     

石蜡相变微胶囊的制备及在建材中的应用

相变微胶囊是应用微胶囊技术,将相变囊芯材料用有机或无机囊壁材料以物理或化学方法包裹起来制备的粒径为0．1～100μm,囊壁厚度为0．01-10μm的有核壳结构的稳定复合相变材料。石蜡烷烃类相变材料是相变微胶囊一种较理想的囊芯材料。主要介绍了用有机、无机类壁材包裹石蜡烷烃类芯材制备石蜡相变微胶囊的研究进展,以及石蜡微胶囊在建材领域的应用现状。     

界面聚合法制备石蜡微胶囊相变材料

相变材料微胶囊是以相变材料为囊芯,无机或有机聚合物、高分子和金属为囊壁的一种颗粒或粉体储能材料。传统树脂等材料制备出的相变材料存在工艺复杂、合成效率低、微观形貌光洁度低等缺点。以石蜡为芯材,聚甲基丙烯酸甲酯(PMMA)为壁材,采用界面聚合法制备石蜡复合相变微胶囊材料。以石蜡和PMMA作为原材料,与本体聚合法相比较,研究发现采用界面聚合法制得的石蜡相变胶囊(Micro PCMs)形貌表面光洁、粒径较小;官能团结构稳定;工艺流程简化,合成效率较高。     

提高石蜡/蜜胺树脂微胶囊芯材含量的影响因素研究

采用原位聚合法,以58~#固体石蜡为芯材,蜜胺树脂为壁材制备了高芯材含量的石蜡/蜜胺树脂相变微胶囊。探讨了乳化剂、乳化水用量和缩聚时pH值对微胶囊储热性能、表观形貌和芯材含量的影响,并采用FTIR、SEM和DSC等对微胶囊的性能进行了表征。研究表明,当使用自制阴离子表面活性剂TA作为乳化剂时,在静电作用下,预聚体分子会均匀分散在芯材液滴的表面,从而使制得的微胶囊光滑圆润且芯材含量有所提高。对微胶囊水洗后再用乙醇洗,其相变焓提高了11.1 J/g,芯材含量高达84.9%。     

相变储能材料的制备及其在石膏基体中的应用研究

制备有机-无机复合壁材微胶囊相变储能材料,并与石膏掺混制备相变储能石膏复合材料。研究了不同壁材结构微胶囊和相变储能石膏复合材料的理化性质。结果表明,复合壁材微胶囊相变储能材料中,微胶囊壁材以无机硅为主,兼有少量有机硅组分,可有效防止壁材开裂且提高微胶囊包覆率;复合壁材微胶囊相变储能材料的相变温度和潜热分别为24.57℃和122.8 J/g,粒径为0.5~1.0μm;掺加微胶囊后,由于石膏结晶状态改变,石膏基体凝结时间延长且强度降低,当掺量达到10%时,相变储能石膏复合材料的潜热为16.1 J/g,具备一定的蓄热调温能力。     

自修复基材微胶囊的制备和表征

以环氧树脂和稀释剂苯甲醇为囊芯,苯乙烯-二乙烯基苯为高分子囊壁材料,采用原位聚合法制备具有自修复功能的微胶囊,并研究了乳化剂、搅拌速度以及反应温度等对微胶囊制备工艺的影响以及成囊机理.结果表明,以阿拉伯树胶和十二烷基苯磺酸钠按质量比1:2复配为乳化剂,最佳工艺条件为:搅拌速度为400 r/min,反应温度75～80℃.红外谱图分析表明,成囊机理是物理包覆,壁材和囊芯之间无化学键形成.     

原位聚合法制备微胶囊相变材料及热工性能研究

以相变蜡、正十八烷和十二醇为芯材,氨基树脂为壁材,采用原位聚合法制备了适合建筑材料使用的微胶囊相变材料,借助扫描电镜图像法、差示扫描量热法和热重分析法对其进行表征,研究了芯材种类、乳化剂用量、预聚体滴加速度对微胶囊相变材料相变温度、相变潜热、热重等热性能的影响。结果表明:正十八烷微胶囊和十二醇微胶囊相变材料近球颗粒表面光滑,粒径分布均匀,成囊率高;当十二醇/氨基树脂微胶囊乳化剂用量为8%,预聚体滴加时间在60 min时,反应较充分,相变温度为23.09℃,相变潜热为61.30 J/g,耐200℃的高温,热稳定性好,适合用于相变储能材料。     

制备条件对石蜡/PMMA相变微胶囊形貌和性能的影响

以石蜡为核心材料,甲基丙烯酸甲酯单体(MMA)为壁材,采用聚合悬浮方法制备了石蜡/聚甲基丙烯酸甲酯(PMMA)相变微胶囊.利用红外光谱仪、扫描电镜、差示扫描量热仪、热重分析仪等对相变微胶囊的表观性能及热性能进行了研究.结果表明,添加5％聚乙烯醇分散剂,水油比为1.5制备的石蜡/PMMA相变微胶囊较为理想,形貌大小均匀;...     

低熔点石蜡微胶囊掺量对相变蓄热砂浆性能的影响

以低熔点石蜡微胶囊为相变储能材料,配以水泥、砂和外加剂制成低熔点石蜡微胶囊相变蓄热砂浆。研究了低熔点石蜡微胶囊掺量对相变蓄热砂浆施工性能、力学性能以及热工性能的影响,并进行了模拟上墙试验。结果表明,石蜡微胶囊掺量对相变蓄热砂浆的性能有着重要的影响,当其掺量在6.5%～10%时,其施工性能、力学性能和热工性能达到最佳;掺量为8%时,相变蓄热砂浆上墙无开裂,适宜于工程应用。     

建筑用相变微胶囊配置方法研究

相变微胶囊是用天然或者合成的聚合物材料将相变芯材包裹的粒子。相变微胶囊由囊壁和囊芯两个部分组成,其中囊芯为相变材料。如何制成具有稳定核壳结构是相变微胶囊制作的难点。本文介绍一种通过反复实验检验的相变微胶囊制作方法。     

The effects of interfacial strength on fractured microcapsule

The effects of interfacial strength on fractured microcapsule are investigated numerically. The interaction between crack and microcapsule embedded in mortar matrix is modeled based on cohesive approach. The microcapsules are modelled with variation of core-shell thickness ratio and potential cracks are represented by pre-inserted cohesive elements along the element boundaries of the mortar matrix, microcapsules core, microcapsule shell, and at the interfaces between these phases. Special attention is given to the effects of cohesive fracture on the microcapsule interface, namely fracture strength, on the load carrying capacity and fracture probability of the microcapsule. The effect of fracture properties on microcapsule is found to be significant factor on the load carrying capacity and crack propagation characteristics. Regardless of core-shell thickness ratio of microcapsule, the load carrying capacity of self-healing material under tension increases as interfacial strength of microcapsule shell increases. In addition, given the fixed fracture strength of the interface of microcapsule shell, the higher the ratio core-shell thickness, the higher the probability of microcapsules being fractured.     

相变微囊复合建材制备及储放热研究

通过采用微乳化技术,将水分散于常温相变储能石蜡中;应用膜孔法,以海藻酸钠包封常温相变石蜡,制得储能微囊;将微囊与石膏基体复合后,制备得到储能建筑材料.研究发现:储能微囊为球形,其粒度分布范围窄;相变含水石蜡微囊储能建筑材料的储能密度得到显著提高,在低于常温相变石蜡固-液相变温度下,其导热系数减小,储/放热时间明显延长,对环境温度的变化响应滞后时间加大,维持恒定温度的时间得到较大延长.     

沥青路面自修复碳纳米管改性微胶囊的制备研究

沥青路面难以探测的早期病害频发,严重影响公路的使用寿命.具有"核-壳"结构的微胶囊可对仪器难以检测的路面微小裂缝病害进行有效、及时的修复.为了进一步提高微胶囊囊壁材料的力学性能及热稳定性能等,本文选择碳纳米管作为改性剂,以脲醛树脂作为微胶囊壁材基质,制备了以碳纳米管改性脲醛树脂为壁材的沥青自修复微胶囊,研究甲醛/尿素比...     

侵蚀环境下微胶囊自修复水泥基材料的修复效果评价

探究了微胶囊掺量、试件预破坏程度、侵蚀溶液pH值以及试件养护龄期对试件修复行为的影响.利用抗压强度回复率和损伤变量来评价试件的自修复效果.结果表明:掺入微胶囊后试件的抗压强度回复率得到提高,不同龄期试件的修复效果均随侵蚀溶液pH值的提高而提高.相同情况下,当微胶囊质量分数为2%时,养护28d的试件修复效果较好,而微胶囊质量分数为4%时,养护180d的试件抗压强度回复率较高.     

Removal of pharmaceuticals from water: Using liquid-core microcapsules as a novel approach

In recent years ever-increasing amounts of pharmaceuticals are being detected in the aquatic environment and in some cases, they have even been discovered in drinking water. Their presence is attributed mainly to the inability of sewage treatment plants to adequately remove these compounds from the sewage influent. The aim of this study was to investigate the feasibility, kinetics and efficiency of using liquid-core microcapsules as a novel methodology, termed capsular perstraction, to remove seven pharmaceuticals commonly found in the environment, from water. The process involves the envelopment of pre-selected organic solvents within a porous hydrogel membrane to form liquid-core microcapsules, which can be used to extract a large range of compounds. Results indicate that this novel approach is capable of extracting the seven chosen compounds rapidly and with a variable efficiency. The simultaneous use of both dibutyl sebacate and oleic acid liquid-core microcapsules at a liquid volume ratio of only 4% (v/v) resulted in the following extractions within 50 min of capsule addition to contaminated water: furosemide 15%; clofibric acid 19%; sulfamethoxazole 22%; carbamazepine 54%; warfarin 80%; metoprolol 90% and diclofenac 100%. The effects of different agitation rates, microcapsule size and membrane thickness on the rate of mass transfer of warfarin into the liquid-core (dibutyl sebacate) of microcapsules was also examined. Results showed that the main rate-limiting step to mass transfer was due to the stagnant organic film (microcapsule size) within the core of the microcapsules. A volumetric mass transfer coefficient of 2.28 × 10⁻⁶ m/s was obtained for the smallest microcapsules, which was nearly 4-fold higher compared to the value (0.6 × 10⁻⁶ m/s) obtained for the largest microcapsules used in this study. Even with this resistance liquid-core microcapsules are still capable of the rapid extraction of the tested compounds and may provide a platform for the safe disposal of the pharmaceuticals after removal.     

环氧树脂/乙基纤维素微胶囊的颗粒特性与缓释性能

采用溶剂蒸发法制备乙基纤维素包覆环氧树脂的自修复用缓释型微胶囊,探讨芯壁比与温度对微胶囊表面形貌的影响,以及转速与乳化剂质量分数对微胶囊粒径分布的影响,采用环境扫描电子显微镜(ESEM)和傅里叶变换红外光谱仪(FTIR)表征微胶囊表观形貌和化学结构,采用紫外-可见分光光度计(UV-VIS)表征微胶囊缓释性能.结果表明:当环氧树脂/乙基纤维素的质量比为1∶1、制备温度30℃、乳化剂(明胶)质量分数为5%以及转速为800r/min时,制备的环氧树脂/乙基纤维素微胶囊形貌圆整、表面孔洞较多、粒径分布较窄且主要分布在75~150μm;环氧树脂/乙基纤维素微胶囊具有良好的缓释性能,在0~1h、1~2h和2~3h时段吸光度增加量随着时间的增加而增加,3~4h时段吸光度增加量出现减少,这主要是随着溶解量的增加,乙醇水溶液对芯材溶解速率放缓所致.     

癸酸微胶囊相变储能砂浆板的温控模拟与验证

以癸酸微胶囊相变储能砂浆板为研究对象,采用试验测试结合数值模拟的方法,验证癸酸微胶囊相变储能砂浆板在建筑围护结构中的温控效果.结果表明:与未掺癸酸微胶囊时相比,掺入2%和4%癸酸微胶囊的相变储能砂浆板导热系数分别降低了8%和21%,而蓄热系数分别升高了3%和11%.在数值模拟与试验验证中,相变储能砂浆板平面温度呈梯度分布,平面整体温度差异不大;随着癸酸微胶囊掺量的提升,相变储能砂浆板在相同时刻的温度上升速度变慢,在同温度下需要的加热时间增加;与未掺癸酸微胶囊的相变储能砂浆板相比,掺4%癸酸微胶囊的相变储能砂浆板相变完成时间延迟20min左右,说明掺入癸酸微胶囊能使相变储能砂浆板的温度增长出现明显延迟,癸酸微胶囊相变储能砂浆板具有良好的温控效果,且该效果随着癸酸微胶囊掺量的增加而变得更好.