Design of melamine-urea-formaldehyde shell microencapsulated aliphatic-based phase change materials for asphalt modification: Preparation and performance evaluation

• Three MUF-aliphatic-based microcapsules were synthesized. • PW@MUF was selected as asphalt modifier with a latent heat of up to 94.8 J/g. • The effect of microcapsules on asphalt properties was analyzed. Three microencapsulated phase change materials (MPCMs) were prepared using paraffin wax (PW), stearic acid (SA), and palmitic acid (PA) as core materials, and melamine-urea–formaldehyde (MUF) resin as the wall material. The prepared microcapsules were tested for thermophysical properties, leakage resistance, mechanical strength, chemical structure, and micromorphology. After selecting the MPCMs with optimal performance, they were incorporated into virgin asphalt and styrene–butadiene–styrene (SBS)-modified asphalt. A dynamic shear rheometer (DSR) and bending beam rheometer (BBR) were employed to assess the rheological properties of the MPCM-modified asphalts. The results indicated that the particle sizes of the three MPCMs ranged from 20 μm to 200 μm, exhibiting a uniform spherical morphology. The phase change material is physically encapsulated within the MUF wall material as a core, thus the MUF resin provides excellent mechanical strength for microcapsules. Among the three microcapsules, the phase change enthalpy values of PW@MUF, PA@MUF, and SA@MUF were measured as 94.8 J/g, 78.29 J/g, and 87.26 J/g, respectively. Notably, PW@MUF exhibited minimal loss, retaining 99.33 % of its mass at 170 °C, which demonstrated its outstanding thermal stability. Rheological tests showed that MPCMs enhanced high-temperature deformation and fatigue resistance, while slightly reducing low-temperature toughness. Increasing MPCM content reduced asphalt’s temperature and stress sensitivity.