Abstract:

To solve the problems of easy leakage, low thermal conductivity and poor mechanical properties of phase change materials, flexible phase change films were prepared by solution blending method of PEG/PLA/Al₂O₃ with biodegradable poly(lactic acid) (PLA) as the substrate, poly(ethylene glycol) (PEG) as the phase change working fluid and alumina (Al₂O₃) as the thermal conductivity additive for thermal energy storage. The phase change films could be curled and folded arbitrarily without breaking, showing good flexibility. The results of the tests on thermal properties, thermal conductivity and degradation properties showed that PEG and PLA had good compatibility, PLA as a supporting substrate effectively prevented the leakage of PEG liquid, and the prepared flexible phase change films had good shape stability. The latent heats during melting and solidification of PEG/PLA were 120.2 J/g and 128.5 J/g, respectively, and the latent heat retention rates were 62.2% and 67.6%, respectively. Adding 20% alumina, the latent heat value was only reduced by 12.5%, while the thermal conductivity was increased by 75%, and the heat transfer efficiency was significantly improved. The degradation rate of PEG/PLA was significantly higher than that of PLA, and the PEG/PLA film could be completely degraded in NaOH solution for about 4 h, which has good environmental friendliness.

Key words: flexible phase change films, alumina, organic phase change materials, polymers, degradable, heat transfer

摘要：

为解决相变材料易泄漏、热导率低和力学性能差的问题，以生物基可降解聚乳酸（PLA）为基底，聚乙二醇（PEG）为相变工质，改性氧化铝（Al₂O₃）为导热添加剂，通过溶液共混法制备PEG/PLA/Al₂O₃柔性相变薄膜，用于热储能。相变薄膜可任意卷曲和折叠而不发生断裂，表现出良好的柔性。对其热性能、导热性能和降解性能等进行测试，结果表明：PEG和PLA具有良好的相容性，PLA作为支撑基底有效防止了PEG液体的泄漏，所制备的柔性相变薄膜具有良好的形状稳定性。PEG/PLA的熔融和凝固过程中的潜热分别为120.2和128.5 J/g，潜热留存率分别为62.2%和67.6%，添加20%的氧化铝，潜热值仅降低12.5%，而热导率提高了75.0%，热传递效率得到明显提升。PEG/PLA的降解速率明显高于PLA，PEG/PLA薄膜在NaOH溶液（pH=13）中4 h左右可完全降解，具有良好的环境友好性。

关键词: 柔性相变薄膜, 氧化铝, 有机相变材料, 聚合物, 可降解, 传热