Preparation Of Polyurethane Solid-solid Phase Change Material And Effect Of Its Modified Asphalt On Temperature Regulation

Asphalt pavement is highly sensitive to temperature.The sudden change of ambient temperature has a very important impact on the service performance and service life of asphalt pavement.In order to reduce the production and development high temperature related diseases of asphalt pavement,from the perspective of self-regulation of asphalt pavement,researchers earlier applied phase change materials to make full use of the latent heat of the material,so as to control the temperature of the pavement actively and reduce the temperature sensitivity of the asphalt pavement.However,in the process of research and application,it is found that the traditional solid-liquid phase change materials have serious leakage and volatilization during the process of high temperature mixing,the volume change of materials will exert adverse effects on the pavement performance of asphalt pavement.In this study,reagent A was used as soft segment,reagent B and reagent C as hard segment,and Polyurethane phase change materials(PUPCMs)were synthesized by prepolymer method.The structural characteristics,heat storage,thermal stability,dynamic mechanical properties and microcrystalline properties of PUPCMs are characterized by various analytical testing methods,the phase transition mechanism of PUPCMs is described.The results show that PUPCMs has the advantages of large phase transition enthalpy,wide selection of phase transition temperature and good thermal stability of phase change cycle,and its unique block structure can effectively overcome the fluidity of solid-liquid phase change material.On this basis,according to the basic requirements of road phase change materials,PUPCMs,which is suitable for modified asphalt is preliminarily selected.The road performance of PUPCMs modified asphalt is tested and analyzed.The temperature regulating mechanism of PUPCMs modified asphalt is preliminarily studied from the aspects of the functional group and micro-morphological structure and other aspects.It is found that PUPCMs and bitumen are only physical blends.The addition of PUPCMs has little effect on the basic technical properties of asphalt,and can improve the high temperature performance and aging resistance of asphalt.The storage stability of PUPCMs modified asphalt is considered,and the recommended value of PUPCMs is 5%.The temperature change of different PUPCMs modified asphalt during the heating process was observed and analyzed.The actual temperature adjustment effect of PUPCMs was evaluated using latent heat accumulated temperature(LHAVT)and latent heat temperature index(LHTI).It was found that under the same environmental conditions,there is a significant difference between the temperature of asphalt specimens with PUPCMs and those specimens without PUPCMs,the maximum temperature difference was up to 13.5℃,and the temperature rise rate of PUPCMs modified asphalt decreases with the increase of PUPCMs content,which indicates that the appropriate increase of PUPCMs content is beneficial to the improvement of PUPCMs’ adjustment ability to asphalt pavement temperature.