Study on the Effect of Soft Segment Length on the Performance of Polyether-Based Polyurethane Modified Asphalt

The molecular structure of the polyurethane soft segment has significant influence on the performance of polyurethane modified asphalt (PUMA). To investigate the effect of soft segment length on the performance of PUMA, three kinds of polytetramethylene ether glycol (PTMEG) with different molar masses were selected to synthesize three polyurethane prepolymers (PUP) with various soft segment lengths. As a result, modifying asphalt with these PUPs lead to three PUMAs. Research showed that the initial decomposition temperature of the PUP rised with the increment of soft segment length and eventually above the base asphalt. The high and low temperature properties of PUMA were enhanced with increasing the soft segment length. However, the dispersion of modifier in the asphalt became worse with higher soft segment length. It should be attributed to the interaction between PUP and asphalt molecules and the crystallization of soft segments. This study provides a good reference for the selection of materials for PUMA.