Properties Of Silica Matrix Composite Phase Change Materials And Asphalt Mixtures

Phase change materials(PCMs)are materials that absorb or release heat through changes in state of matter and have been widely used in industrial and construction fields due to their energy storage properties.The emergence of PCMs provides a new way of thinking for road surface cooling technology.In this paper,poly(ethylene glycol)(PEG)and ethylene glycol distearate(EGD)with suitable phase change temperature(Tm)were selected as PCMs.Silica(SiO2)-supported composite phase change materials(CPCMs)was prepared by sol-gel method.Ceramsite(CS)-supported CPCMs was prepared by vacuum impregnation method.The novolac epoxy resins(NER)and curing agent 593(CR593)were used to encapsulating the CPCMs(E-CPCMs)to ensure the thermal and chemical stability of the CPCMs.The microstructure of the CPCMs,chemical compatibility between the PCMs and the matrix,thermal stability and thermal properties were studied by scanning electron microscope(SEM),X-ray diffraction(XRD)and Fourier transformation infrared(FTIR),thermogravimetric(TG)analysis experiment and differential scanning calorimetry(DSC)respectively.The thermal reliability,exudation stability and the thermal storage/release properties were tested by the self-designed accelerated thermal cycling test,Ieakage test and the thermal storage/release test.The results show that the combination of PCMs and matrix of the two types of PCMs is physical combination,and the compatibility between the PCMs and the matrix is good.The results of TG experiments show that the CPCMs can satisfy the mixing temperature requirements of the asphalt mixture.DSC results show that the CPCMs has considerable phase transition enthalpy(AHm)and suitable Tm,and the thermal properties are good.The results of thermal cycling experiments show that the AHm and FTIR spectrum of the CPCMs have no significant change after l00 melting/crystallizing processes,and the service life of the CPCMs is longer.Leakage experiments show that the leakage of CPCMs is greatly reduced after encapsulation.The results of accelerated thermal cycling test show that the CPCMs exhibits a temperature platform during the rise and fall of the temperature,which reduces the temperature rise and fall rate.In addition,the preferred E-PEG/CS and PEG/SiO2 are used to replace the mineral aggregates of the corresponding particle size in the conventional asphalt mixture to prepare various kinds of asphalt mixtures,and the temperatures of the upper and bottom surface of the specimens are dynamically tracked to explore the cooling effect.The road performance of asphalt mixture such as high temperature stability,low temperature crack resistance and water stability were evaluated.The upper surface of E-PEG/CS has a maximum temperature drop of 9.1?,and the bottom surface of PEG/SiO2 has a maximum temperature drop of 15.4?.The immersion stability of the mixture specimens satisfies the requirements,the high temperature stability decreases slightly,and the water stability slightly increases.