A nanocomposite phase change thermal energy storage material was prepared by intercalating stearic acid into the nano-layers of modified bentonite in liquid media. XRD patterns showed that the intergallery distance of...A nanocomposite phase change thermal energy storage material was prepared by intercalating stearic acid into the nano-layers of modified bentonite in liquid media. XRD patterns showed that the intergallery distance of the nanocomposite material was larger than that of modified bentonite owing to intercalating of stearic acid. The phase change temperature of the nanocomposite phase change material was different from that of stearic acid,and its phase change latent heat was equivalent to the calculated value based on the mass ratio of stearic acid in the composite. The experimental results of thermal energy storage and release indicated that the heat transfer rate of the nanocomposite material was obviously higher than that of stearic acid. After the nanocomposite experienced 1500 times cooling-heating cyclic test,its phase change temperature and latent heat showed little change,which suggested that the stearic acid/bentonite nanocomposite phase change material exhibited good stability of structure and properties. This method of intercalating organic phase change material into the nano-layers of bentonite provides a new route to prepare phase change materials with high performances.展开更多
Mg/Al layered double hydroxide(LDH) was treated with stearic acid by a wet method. The modified double hydroxide showed good dispersion and floatation property with their layer structure being remained almost unchanged.
采用"熔融吸附-模压成型"的方法制备了膨胀石墨(EG)为多孔基体、硬脂酸(SA)为相变材料的EG/SA定形相变储能复合材料,通过微观形貌、热物性和热稳定性测试,分析了膨胀石墨的膨胀度对EG/SA定形相变储能复合材料的热性能影响规律...采用"熔融吸附-模压成型"的方法制备了膨胀石墨(EG)为多孔基体、硬脂酸(SA)为相变材料的EG/SA定形相变储能复合材料,通过微观形貌、热物性和热稳定性测试,分析了膨胀石墨的膨胀度对EG/SA定形相变储能复合材料的热性能影响规律,并通过加热/冷却实验对不同参数的定形相变储能复合材料的储/放热性能进行了分析比较.研究表明采用高膨胀度EG更有利于提高SA在EG多孔基体中的分布均匀性和储能复合材料的热导率,当EG质量分数为20%时其径向导热系数最高达19.6 W m^(-1)K^(-1),相比纯SA提高了110倍;EG的高膨胀度对SA相变过程中的液相封装具有明显的改善作用,高膨胀度EG为基体的定形相变储能复合材料具有很好的热稳定性;EG/SA定形相变储能复合材料的储/放热时间约为纯相变材料的1/8~1/4,具有高导热、无泄漏等优点.展开更多
The effects of esterification with stearic acid on the crystallizing behavior,thermal stability and resistance to water of polyvinyl alcohol(PVA) were studied by using IR, WAXD, DSC, TG and water resistance test.The r...The effects of esterification with stearic acid on the crystallizing behavior,thermal stability and resistance to water of polyvinyl alcohol(PVA) were studied by using IR, WAXD, DSC, TG and water resistance test.The results show that the esterification of PVA with stearic acid could take place in the presence of dibutyltin dilaurate at 128℃.—OOC(CH\-2) 16 CH 3 groups are introduced into PVA molecular chains during esterification.With increasing the reaction time, the thermal stability and water resistance of PVA are improved.However, the crystallinity and melting temperature of PVA are decreased. As reaction time exceeds 16h,the crystalline structure of PVA disappears according to WAXD and DSC curves.The initial decomposition temperature after esterification is over 200℃,much higher than that of PVA.These results suggest a method for improving the thermal stability and water resistance of PVA.展开更多
文摘A nanocomposite phase change thermal energy storage material was prepared by intercalating stearic acid into the nano-layers of modified bentonite in liquid media. XRD patterns showed that the intergallery distance of the nanocomposite material was larger than that of modified bentonite owing to intercalating of stearic acid. The phase change temperature of the nanocomposite phase change material was different from that of stearic acid,and its phase change latent heat was equivalent to the calculated value based on the mass ratio of stearic acid in the composite. The experimental results of thermal energy storage and release indicated that the heat transfer rate of the nanocomposite material was obviously higher than that of stearic acid. After the nanocomposite experienced 1500 times cooling-heating cyclic test,its phase change temperature and latent heat showed little change,which suggested that the stearic acid/bentonite nanocomposite phase change material exhibited good stability of structure and properties. This method of intercalating organic phase change material into the nano-layers of bentonite provides a new route to prepare phase change materials with high performances.
文摘Mg/Al layered double hydroxide(LDH) was treated with stearic acid by a wet method. The modified double hydroxide showed good dispersion and floatation property with their layer structure being remained almost unchanged.
文摘采用"熔融吸附-模压成型"的方法制备了膨胀石墨(EG)为多孔基体、硬脂酸(SA)为相变材料的EG/SA定形相变储能复合材料,通过微观形貌、热物性和热稳定性测试,分析了膨胀石墨的膨胀度对EG/SA定形相变储能复合材料的热性能影响规律,并通过加热/冷却实验对不同参数的定形相变储能复合材料的储/放热性能进行了分析比较.研究表明采用高膨胀度EG更有利于提高SA在EG多孔基体中的分布均匀性和储能复合材料的热导率,当EG质量分数为20%时其径向导热系数最高达19.6 W m^(-1)K^(-1),相比纯SA提高了110倍;EG的高膨胀度对SA相变过程中的液相封装具有明显的改善作用,高膨胀度EG为基体的定形相变储能复合材料具有很好的热稳定性;EG/SA定形相变储能复合材料的储/放热时间约为纯相变材料的1/8~1/4,具有高导热、无泄漏等优点.
文摘The effects of esterification with stearic acid on the crystallizing behavior,thermal stability and resistance to water of polyvinyl alcohol(PVA) were studied by using IR, WAXD, DSC, TG and water resistance test.The results show that the esterification of PVA with stearic acid could take place in the presence of dibutyltin dilaurate at 128℃.—OOC(CH\-2) 16 CH 3 groups are introduced into PVA molecular chains during esterification.With increasing the reaction time, the thermal stability and water resistance of PVA are improved.However, the crystallinity and melting temperature of PVA are decreased. As reaction time exceeds 16h,the crystalline structure of PVA disappears according to WAXD and DSC curves.The initial decomposition temperature after esterification is over 200℃,much higher than that of PVA.These results suggest a method for improving the thermal stability and water resistance of PVA.
