Preparation and temperature-sensitive response behavior of graphene-carbon nanotubes-polylactic acid/polyethylene glycol phase change energy storage composites
In this study,a graphene-carbon nanotube-poly(lactic acid)/polyethylene glycol(Gr-CNT-PLA/PEG)phase change energy storage composite material was prepared using a solution-melt blending method.The effects of conductive particles and PEG on the crystallization behavior,electrical conductivity,and temperature-sensitive response of the PLA phase change energy storage composite material were investigated in detail.During the solu-tion-melt blending process,the two-dimensional graphene and one-dimensional carbon nanotubes can physically hybridize into three-dimensional Gr-CNT hybrid particles under the influence of thermodynamic and kinetic factors,improving the dispersion of conductive particles in the composite material and reducing the percolation threshold to about 0.51wt%.Furthermore,the electrical conductivity and crystallization behavior of the Gr-CNT-PLA/PEG composite material are further improved by the interaction between PEG phase change energy storage material and conductive particles,and the crystallization temperature is increased from 100℃(PLA)to about 130℃((Gr-CNT50)0.6-PLA/PEG10).In the constant temperature-resistance test,the conductivity of the Gr-CNT-PLA/PEG composite material decreases and then increases with the increase of isothermal heat treatment temperature.In the cyclic temperature-resistance test,the Gr-CNT-PLA composite material exhibites low-temperature PTC and high-temperature NTC effects in the cyclic temperature range of 37℃to 140℃.Through the synergistic regulation of phase change energy storage material PEG and cyclic temperature value,the Gr-CNT-PLA/PEG composite material exhibites a good phase transition energy storage platform during cooling,successfully achieving a monotonic PTC effect and high-temperature sensitivity,with a sensitivity(ΔR/R0)up to 3 000%.Moreover,with the increase of PEG mass content,the energy storage platform of the composite material can be effectively widened,up to 16.28 min,providing a basis for the preparation of high-sensitivity temperature sensors.
hybridized conductive particlespolyethylene glycolpolylactic acidconductivityphase change energy storagetemperature response behavior
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