Microencapsulated binary eutectic phase change materials with high energy storage capabilities for asphalt binders

Octanoic acid (OA) and tetradecane (TD) underwent mixing and the eutectic method to improve the energy storage capacities of phase change materials (PCMs) that were reduced by microencapsulation. A microencapsulated phase change material (MPCM) was synthesized by using nano-TiO2 and polyvinyl alcohol reinforced melamine formaldehyde resin as the wall and wrapping materials of OA-TD. The chemical composition, morphological structure, thermal properties, and thermal stability of the MPCM were analyzed. Additionally, the effects of microcapsules on asphalt properties and the ability to regulate asphalt temperature were investigated. The results showed that neither eutectic nor microencapsulated encapsulation produced new characteristic peaks. The MPCMs were transparent spheres with particle sizes of 1-50 mu m and good formability. Compared with OA and TD, the enthalpy values of the exothermic phase transition process of OA-TD increased by 67.6% and 10.7%, respectively, and the phase transition temperature ranges increased by 53.5% and 26.7%, respectively. The exothermic enthalpy of the formed MPCM is 140.61 J/g, which provides latent heat and good thermal stability when mixed with asphalt. Temperature regulation tests demonstrated that MPCM effectively reduced the cooling rate and peak temperature of asphalt. The addition of MPCM to asphalt resulted in a decrease in penetration and ductility, but an increase in softening point. At high temperatures, MPCM enhanced the apparent viscosity, composite modulus, and rutting factor of asphalt, thereby improving its high-temperature deformation resistance.