Preparation and application of carboxylated carbon nanotube-modified melamine resin phase change materials with high photothermal conversion efficiency.

High thermal conductivity nanoparticles are often used to enhance the mechanical properties and thermal conductivity of microencapsulated phase change materials (MEPCMs). However, microcapsules are usually prepared by in situ polymerization of complex prepolymers. In this paper, carboxylated carbon nanotubes (C-CNTs) modified melamine resin MEPCMs with unique square structures were prepared by in situ polymerization of monomers through a simple process. The research mainly focuses on the effects of reaction temperature, paraffin dosage, modifier type, quantity, and addition method on the performance of melamine resin MEPCMs modified with C-CNTs. The melt permeability, thermal conductivity, thermal stability, and chemical structure of the modified MEPCMs were characterized. The results show that when the polymerization temperature is 60 °C, the core material is 15 g of paraffin, and the modifier is 1.5% C-CNTs, the comprehensive performance of the modified MEPCMs is the best: the phase change enthalpy is 113.1 J/g, the thermal conductivity is 0.2354 W/m·K, and the melting permeability is 18.83%, which indicates high thermal stability. Under simulated sunlight irradiation, the time required for the temperature of the modified microcapsule system to rise to 65 °C was reduced by 63.25%. It has high application potential in solar photothermal conversion materials. [ABSTRACT FROM AUTHOR]