Preparation of low-temperature microencapsulated phase change materials and evaluation of their effect on the properties of asphalt binders

Organic eutectic phase change materials (PCMs) hold significant promise as thermal storage agents for regulating the temperature of asphalt pavements. This study aims to evaluate the properties of low-temperature micro- encapsulated phase change materials (MPCMs) and their effect on modifying virgin asphalt. Three types of binary eutectic MPCMs were prepared, with tetradecane eutectically mixed with lauric, capric, and myristic acids, forming the composite core of the MPCMs. Melamine-urea-formaldehyde (MUF) resin was used as the wall material. The properties of the MPCMs were characterized through thermophysical and thermal stability analyses, micro-morphology observation, infrared spectroscopy, and mechanical strength tests. The preferred microcapsules were then blended into virgin asphalt at dosages of 3 %, 5 %, 7 %, and 9 %, and the thermal properties, thermoregulation capability, and rheological properties of the MPCM-modified asphalt were evaluated. The results indicated that the MPCMs had a spherical structure with particle sizes ranging from 20 mu m to 250 mu m, and the wall and core materials physically formed the microcapsules. Among them, 1# MPCM exhibited the highest enthalpy and excellent thermal stability. Additionally, the superior mechanical properties of 1# MPCM minimized breakage during the asphalt mixing process. Moreover, the MPCM-modified asphalt demonstrated a significant thermal hysteresis effect during temperature increases, with a maximum temperature difference of 5.9 degrees C compared to virgin asphalt. The leakage of MPCMs following phase change results in reduced stiffness of the MPCM-modified asphalt at high temperatures, impacting its thermal stability. However, the inclusion of MPCMs substantially decreases the asphalt's temperature susceptibility, improving its adaptability across different temperature conditions and notably enhancing crack resistance in low-temperature environments.