The Study On Preparation And Performances Of Porous Phase Change Material Composites

Porous materials possessed pore structure and large specific surface area. Porous materials are used to encapsulate phase change material(PCM) to form form-stable phase change material composites in order to resolve the leakage problem of the solid-liquid phase change material composites and improve its latent heat and thermal conductivity. In this paper, three kinds of porous materials halloysite nanotubes(HNTs), porous carbon and conjugated microporous polymers(CMP)) were selected to use as supporting materials, paraffin wax, myristic acid(MA), palmitic acid(PA) and stearic acid(SA) were selected to use as phase change materials to prepare phase change material composites. And a variety of analysis methods of SEM, TEM, XRD, DSC and TGA were performed to measure the pore characteristics and thermal stability of the porous materials and thermal properties of the PCMs composites.Part I, purified HNTs(p-HNTs) and PDMS-treated HNTs(PDMS-HNTs) were use as supporting materials, paraffin wax, MA, PA and SA were use as phase change materials to prepared a series of PCM composites. The SEM and the TEM images show that the phase change materials were loaded at the outer and inner surface of the two kinds of supporting materials. The DSC results suggest that the PDMS-HNTs/PCMs composites present high latent heats that between 44.7 J g-1 and 72.1 J g-1. The TGA results suggest that there was no decomposition observed for the PDMS-HNTs/PCM composite at 180 oC, indicating their good thermal stability. The thermal conductivities of the PDMS-HNTs/PCM composites were measured ranging from 0.432 W m-1 K-1 to 0.706 W m-1 K-1, indicating that the PDMS-HNTs could significantly improve the thermal conductivities of PCM composites.Part II, one porous carbon(named H-CS and carbonized from walnut green peels) was used as supporting materials, MA, PA and SA were use as phase change materials to prepared PCM composites. The SEM and the TEM images show that the surface of the H-CS are loose, porous and the surface of the H-CS/PCM composites are full of phase change materials. The H-CS/PCM composites present high latent heats that between 61.25 J g-1 and 81.6 J g-1. Moreover, there was no decomposition for the PDMS-HNTs/PCM composite at 160 oC, suggesting their good thermal stability.Part III, superhydrophobic and superoleophilic conjugated microporous polymers nanotubes(CMPN-1 and CMPN-2) were synthesized to use as supporting materials and MA, PA and SA were use as phase change materials to prepared PCM composites. The SEM and the TEM images show that the phase change materials were loaded at the outer and inner surface of CMPN-1 and CMPN-2. The TGA results suggested that the CMPN-1 and CMPN-2 have great thermal stability. The DSC results suggested that the CMPNs/PCMs composites presented high latent heats(90.86 J g-1 ~ 141.06 J g-1), and changed slightly after 200 thermal cycling, which indicated that the CMPNs/PCMs composites have little leakage and have a good thermal recycling ability. The thermal conductivities of the CMPNs/PCM composites were measured ranging from 150.12% to 182.56% compored by pure PCM, suggesting that the CMPN-1 and CMPN-2 could enhance the thermal conductivities of PCM composites.