Tao Liu,Naisheng Guo,Xin Jin,Yiqiu Tan,Zhanping You,Shichao Cui,Zhaoyang Chu,Chenze Fang
Phase change materials (PCMs) can regulate asphalt temperature through thermal storage properties to prevent thermal damage in asphalt pavements. However, the effects of PCMs on the thermoregulation and rheological properties of asphalt require further study. In this study, polyurethane solid–solid phase change materials (PUSSPCMs) were prepared to impart thermoregulation properties to asphalt, and the effects of PUSSPCMs on the rheological properties and microscopic characterization of asphalt were investigated. The PUSSPCMs were produced by different soft segment mass fractions (70 %, 80 %, and 90 %), and they were used to prepare modified asphalt with varying contents (3 %, 5 %, and 7 %). Thermoregulation testing system, dynamic shear rheology (DSR), bending beam rheology (BBR) tests, differential scanning calorimetry (DSC), infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and atomic force microscopy (AFM) were conducted to determine the thermoregulation, rheological properties, and modification mechanism of PUSSPCM-modified asphalt, respectively. The results show that the thermoregulation property of PUSSPCM-modified asphalt improves with the increase of soft segment mass fraction and content, 7 % P90 asphalt exhibits the best thermoregulation property with the excellent delayed time (1105 s) and temperature difference (7.1 ℃). The high-temperature rutting resistance of the modified asphalt is enhanced by decreasing the soft segment mass fraction and increasing the content of PUSSPCMs, with the 7 % P70 being the best asphalt type. The 7 % P90 asphalt exhibits the optimum low-temperature creep performance due to a higher soft segment mass fraction. The modified asphalt may be a physical modification since no new characteristic peaks appear. With the increase of soft segment mass fraction, the PUSSPCMs in asphalt transform from elastomer to a ribbon-like structure. Furthermore, the microscopic roughness ( S q ) and Young's modulus of the modified asphalt decline with the increase in soft segment mass fraction and content of PUSSPCMs, implying an increase in microscopic crack resistance and a decrease in elasticity.
Tao Liu,Naisheng Guo,Zhanping You,Yiqiu Tan,Chenze Fang
The purpose of this study is to assess the effect of polyurethane solid-solid phase change materials (PUSSPCMs) and polyethylene glycol (PEG4000) on the thermoregulatory and rheological properties of asphalt , as well as their potential for regulating asphalt pavement temperature. The chemical and thermodynamic characteristics of PEG4000 and PUSSPCMs were investigated using infrared spectroscopy (FTIR), adsorption test, polarized light microscopy (POM), X-ray diffractometer (XRD), differential scanning calorimetry (DSC), thermogravimetric (TG), and atomic force microscopy (AFM). Meanwhile, the effects of PEG4000 and PUSSPCMs on asphalt road performance and micromorphology were determined by tests of thermoregulation, three major indexes, DSR segregation, and scanning electron microscopy (SEM). The results indicate that PUSSPCMs have no hydroxyl characteristic peaks of PEG4000 and isocyanate bonds after the complete reaction. PUSSPCMs exhibit better phase stability over PEG4000, the soft segment for thermal storage changes from crystalline to amorphous and is limited by the hard segment micro-region to maintain a stable solid phase. PUSSPCMs exhibit slightly weaker thermal storage properties than PEG4000, while the thermal stability and elastic modulus are stronger. PUSSPCMs-modified asphalt performs lower thermoregulation properties than PEG4000-modified asphalt, which improves with the increasing soft segments. Furthermore, the advantages of PUSSPCMs-modified asphalt are in terms of basic physical, rheological properties and storage stability. The micromorphology of PUSSPCMs-modified asphalt shows no visible cracks compared to PEG4000-modified asphalt and flattens with soft segment rises, which contributes to the thermoregulation and rheological properties of asphalt.
Shi Wenshuo,Wei Kun,Fan Yuzhe,Wang Xiaoqing,Shi Jiahao,Wang Sifan,Cheng Peng
Transition temperature is significant in determining applications of phase change materials. In this paper, PEG2000 and PEG4000 were used as soft segments and MDI and 3,3ʹ-Dichloro-4,4ʹ-diaminodiphenylmethane (MOCA) were used as hard segments. Several polyurethane solid–solid phase change materials (PUSSPCMs) were synthesized by adjusting the mass ratio of PEG4000 and PEG2000. Based on the differential scanning calorimeter test, this paper studied the relationship between the mass ratio of PEG2000 and the phase transition temperature. The influence mechanism of phase change temperature was revealed from molecular structure, crystallization properties, and surface morphology. Furthermore, PUSSPCMs were tested for leakage and the thermal stability. The results showed that the synthesized PUSSPCMs had no liquid leakage during the heating process. There was a good linear relationship between the mass ratio of PEG2000 and phase transition temperature. The thermal decomposition onset temperature was above 230 °C.
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