通过冷冻干燥技术制备了不同多孔特征的聚乙烯醇(PVA)骨架,采用真空浸渍法将聚乙二醇(PEG)、硬脂酸(SA)、石蜡(PW)这3种有机相变材料(PCMs)吸附在PVA骨架内,研究了不同孔特征的PVA骨架对复合PCMs性能的影响以及PVA骨架吸附不同相变材料的性能。结果表明:PVA骨架的孔隙率和孔容由PVA前驱溶液的浓度决定,浓度越大,PVA的孔隙率和孔容越小,但其力学性能越好,7%PVA骨架在80%应变时的压缩应力达到了5.57MPa。PVA骨架与PCMs之间的界面热阻使复合PCMs的导热系数相对于纯PCMs有所降低,且孔隙率越小这种降低越明显。相对于SA和PW,PVA骨架在支撑PEG时表现出更好的形状稳定性和负载能力。同时,PVAs-PEG复合相变材料表现出更高的结晶度(Fc>92%)和更小的界面热阻,表明PVA骨架更适合用作PEG的支撑材料。
Polyvinyl alcohol (PVA) frameworks with different porous characteristics were prepared by freeze-drying technology,and three organic phase change materials (PCMs),polyethylene glycol (PEG),stearic acid (SA),and paraffin wax (PW),were adsorbed into the PVA framework.The effect of PVA frameworks with different pore characteristics on the performance of composite PCMs and the adsorption performance of PVA frameworks for different phase change materials were investigated.The study found that the porosity and pore volume of the PVA framework were determined by the concentration of the PVA precursor solution.The higher the concentration,the smaller the porosity and pore volume of PVA,but the better its mechanical properties,and the compressive stress of 7% PVA framework at 80% strain reached 5.57MPa.The interfacial thermal resistance between the PVA framework and PCMs reduced the thermal conductivity of composite PCMs compared with pure PCMs,and the decrease was more obvious with smaller porosity.Relative to SA and PW,the PVA framework exhibited better shape stability and loading capacity when supporting PEG.Meanwhile,the PVAs-PEG composite phase change material presented higher crystallinity (Fc>92%) and smaller interfacial thermal resistance,indicating that the PVA framework was more suitable as a support material for PEG.
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