Thermal storage properties of polyurethane solid-solid phase-change material with low phase-change temperature and its effects on performance of asphalt binders

Abstract

Preparing phase change materials (PCMs) with appropriate phase-change temperatures is of great significance in preventing the low-temperature disease in pavements. In this study, several polyurethane solid-solid PCM (PUPCM) samples were prepared via a two-step condensation reaction of polyethylene glycol, polytetramethylene ether glycol, 4,4′-diphenyl methane diisocyanate, and 4,4′-methylenebis-(2-chloroaniline). Considering the phase-change temperature and thermal stability, a PUPCM sample with a suitable molar ratio was used for the asphalt modification. The prepared materials were characterised by Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, three indices of asphalt and viscosity tests, rotational viscometer tests, and other techniques. PUPCM samples with different soft and hard segment ratios exhibit different phase-change temperatures and enthalpies, and their physical, chemical, and phase-change properties are stable. When the ratio of soft and hard segments is 8:2 (PU-14), the freezing and melting temperatures were −2.7 °C and 12.9 °C, and the enthalpy was 46.8 J/g. The PUPCM modification of asphalt only involves physical miscibility. Adding PUPCM negligibly affects the high- and low-temperature performances of the modified asphalt binder. The viscosity of the PUPCM-modified asphalt binder is slightly higher than that of the original asphalt binder, and the storage stability of the modified asphalt binder is satisfactory. The addition of PUPCM improves the anti-ageing performance of asphalt, and the improvement becomes significant with increasing PUPCM content. Moreover, the phase-change energy storage properties of PUPCM in asphalt were found to be satisfactory. Hence, PUPCMs can potentially be used for asphalt modification to further improve the low-temperature performance of pavements.