科研之友
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摘要
A facile method to prepare phase change materials (PCM) microcapsules containing paraffin was developed, through in-situ polymerization combined with hydrothermal process. Paraffin melting at 20 C was used as PCM. The hybrid microcapsules' shell was prepared by copolymerizing styrene (St), acrylic acid (AA), n-butyl acrylate (BA), and pentaerythritol triacrylate (PETA) which were employed as crosslinldng agents. The initiator could be spared because the synthesis reaction was carried out in high temperature hydrothermal reaction. Microcapsules with well-defined core-shell structure were obtained, and their morphologies were studied by (scanning electronic microscope) SEM and (transmission electron microscopy) TEM. Under hydrothermal conditions, the flexibility and strength of the shells were enhanced by PETA added, which made it possible to form amore uniform thickness of shell materials, and bigger expansion volumes inside the microcapsules than the traditional in-situ polymerization. The expansion space was very important for the stability of PCM microcapsules, which could allow PCM expand and shrink inside the microcapsules, and the flexible shells could keep themselves intact in repeated absorbing-releasing thermal transmittance process. Innovatively, the deformations of these shells caused by the expansion and shrinkage in this process could recover to a certain extent after being soaked in water without loss of enthalpy values. The results of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) indicated that the PCM microcapsules have high heat storage capability and good thermal stability.
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