Polyethylene glycol (PEG)/ expanded vermiculite (EVMT) shape-stabilized composite phase change material (ss-CPCM) was prepared by a facile vacuum impregnation method. The maximum mass percentage for PEG retained in ss-CPCM was 75.1 wt.% due to specific non-uniform flat layers pore structure of EVMT. The scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FT-IR) analysis results indicated that the melted PEG was adsorbed on the surface and completely dispersed into the pores of EVMT and no chemical changes took place during the heating and cooling processes. X-ray diffraction (XRD) results showed that the crystal structure of PEG was not destroyed after impregnation whereas the crystallization process of PEG was greatly restrained. Differential scanning calorimetry (DSC) results indicated that ss-CPCM melted at 57.61°C with a latent heat of 103.1 J/g and solidified at 33.19°C with a latent heat of 88.29 J/g. In addition, the thermal conductivity of ss-CPCM reached 0.418W/m K. The ss-CPCM can be considered as promising candidate materials for building applications due to their suitable phase change temperature, large latent heat and excellent chemical compatibility.
In this research, high strength and lightweight wall materials were made from oil shale ash (OSA) by grinding, mixing, casting molding, autoclave curing processes, et al. Factors influencing the bulk density and compressive strength of the wall materials were discussed in detail. X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM) analysis were used to characterize the samples. The results indicated that the compressive strength can reach up to 13.42 MPa when the bulk density reduced to 1.11g/cm3 introduced 72.00 % of OSA, the wall materials showed thermal conductivity of 0.12~0.14 W/m k. The main hydration products of the wall materials were calcium hydroxide [Ca (OH)2], C-S-H gelation and hydrogrossular [Ca3Al2(SiO4)(OH)8]. These hydration products are prodominently C-S-H gelation bonded the solid raw materials together tightly and play a great contribution to the compressive strength of wall materials.
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