癸酸-棕榈酸二元复合相变材料的相变特性研究

通过熔融共混法制备一系列二元脂肪酸复合相变材料,并利用步冷曲线法确定癸酸-棕榈酸(CA-PA)二元复合相变材料的最佳质量配比为86∶14,其共晶温度为22.1℃。采用傅里叶红外光谱仪(FT-IR)、冷热加速循环实验和瞬态平面热源法(TPS)等研究CA-PA复合相变材料的结构与性能,发现CA-PA的FT-IR曲线上同时存在CA和PA的特征吸收峰,表明CA与PA是通过分子力作用在一起的。然后对CA-PA进行400次5~80℃冷热加速循环后,发现其相变温度变化不大于0.5℃,可见CA-PA热稳定性良好,且导热系数为0.151 W/(m·K)。同时,根据差示扫描量热仪(DSC)分析得到CA-PA的相变温度和相变潜热分别为21.78℃和154.7 J/g,这与通过步冷曲线得到的共晶温度十分符合,因此该CA-PA复合相变材料适用于建筑节能和热回收领域。

PHASE TRANSITION PROPERTIES OF CAPRIC-PALMITIC ACID BINARY COMPOSITE PHASE CHANGE MATERIALS

The binary fatty acid composite phase change materials were prepared by melt blending method.The optimum mass ratio of capric-palmitic acid(CA-PA)binary composite phase change materials is equated to 86∶14,and eutectic temperature of CA-PA up to 22.1℃was determined with cooling curve method.The structure and properties of the composite phase change materials were characterized by fourier transform infrared spectrometer(FT-IR),accelerated thermal cycling experiments and transient plane source method(TPS),and the characteristic absorption peaks of CA and PA were found to coexist in FT-IR curve of CA-PA,indicating that CA and PA are combined by molecular forces.After thermal cycling between 5℃and 80℃in 400 times for CA-PA,the change of the phase transition temperature is not more than 0.5℃,which shows that CA-PA has good thermal stability,and the thermal conductivity of CA-PA is 0.151 W/(m·K).According to the differential scanning calorimeter(DSC),the phase change temperature and latent heat of the composite are 21.78℃and 154.7 J/g respectively,which is better agreement with the eutectic temperature obtained by cooling curve.Therefore,the CA-PA binary composite phase change materials is suitable for the building energy conservation and heat recovery.