Phase change materials (PCM) have gained extensive attention in thermal energy storage applications. In this work, microencapsulation of vegetable-derived palmitic acid (PA) in bio-based polylactic acid (PLA) shell by solvent evaporation and oil-in-water emulsification was investigated. Fourier transform infrared spectroscopy and scanning electron microscopy were conducted to confirm the successful encapsulation of PA in PLA shells. Differential scanning calorimetry was performed to evaluate the thermal properties, thermal reliability, and core content of the fabricated PCM microcapsules (microPCM). Through a series of parametric studies, the effects of PCM and solvent content, oil phase-to-aqueous phase ratio, as well as surfactant type and content on the morphology, particle size, and thermal properties of the PCM microcapsules were investigated. Experimental results showed that PVA was a superior emulsifier to SDS in the emulsion systems being studied. There also existed an optimal PVA concentration to reduce the average size of microPCM. When the PVA concentration was above this optimal level, the emulsifier molecules tend to form micelles among themselves. This led to the adhesion of tiny microspheres on the surface of microPCM as well as larger microPCM. In short, this work has demonstrated the possibility of using the solvent evaporation method to fabricate 100% bio-based PCM-polymer microcapsules for thermal energy storage applications.

中文翻译：

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用于热能存储的100％生物基聚乳酸/棕榈酸微胶囊的制备和表征。

相变材料（PCM）在热能存储应用中得到了广泛的关注。在这项工作中，通过溶剂蒸发和水包油乳化技术研究了植物性棕榈酸（PA）在生物基聚乳酸（PLA）壳中的微囊化。进行了傅里叶变换红外光谱和扫描电子显微镜，以确认PA外壳中PA的成功封装。进行差示扫描量热法以评估所制造的PCM微胶囊（microPCM）的热性质，热可靠性和芯含量。通过一系列参数研究，研究了PCM和溶剂含量，油相与水相的比率以及表面活性剂类型和含量对PCM微胶囊的形貌，粒度和热性能的影响。实验结果表明，在所研究的乳液体系中，PVA是优于SDS的乳化剂。还存在最佳的PVA浓度以减小microPCM的平均尺寸。当PVA浓度高于该最佳水平时，乳化剂分子趋于在它们之间形成胶束。这导致微小的微球粘附在microPCM以及较大的microPCM的表面上。简而言之，这项工作证明了使用溶剂蒸发法制造100％生物基PCM聚合物微囊用于热能存储应用的可能性。当PVA浓度高于该最佳水平时，乳化剂分子趋于在它们之间形成胶束。这导致微小的微球粘附在microPCM以及较大的microPCM的表面上。简而言之，这项工作证明了使用溶剂蒸发法制造100％生物基PCM聚合物微囊用于热能存储应用的可能性。当PVA浓度高于该最佳水平时，乳化剂分子趋于在它们之间形成胶束。这导致微小的微球粘附在microPCM以及较大的microPCM的表面上。简而言之，这项工作证明了使用溶剂蒸发法制造100％生物基PCM聚合物微囊用于热能存储应用的可能性。