The Research Of Formation And Stability Of Multiphase In Polymer Modified Asphalt System

The performances of the modified asphalt were mainly influenced by temperature, shear stress, shear time and producing technology. In this paper, The four modified asphalt methods such as high-speed shear mixer method, solvent method were studied for comparison. The results showed that The performances of modified asphalts made by solvent method and high polymer content method were better than those of modified asphalts made by high-speed shear mixer method and direct method.The performances of modified asphalt by adding stabilizer agent with twin screw extruder were good compared to those of modified asphalt by solvent method and high contents polymer modified asphalt.The concentration of basic material had little influence on the performances of modified asphalt. The performances of modified asphalt were enhanced with the increase of shear time of twin screw extruder. The softening-point and the ductility were improved slightly with increased temperature. The process method had large influence on the performances of modified asphalt. The The twin screw extruder was used to modify asphalt in this paper. The performances of modified asphalt at various conditions, such as temperature, shear velocity, shear time and the optimum operation technology were investigated. The changing rules were explored as well. The experimental results showed that the SBS could be dispersed evenly by twin-screw extruder and the performances of asphalt could be improved. Shear time, shear velocity and producing temperature were three factors influencing the modified asphalt performances. Shear time and shear velocity were the most important factors. The softening point and ductility were enhanced with the increase of shear time and shear velocity, but the penetration was decreased. The effect of temperature from 130℃to 180℃on the modified asphalt performances was little comparelly.Two kinds asphalt with different components and two kinds polymer modifier were explored in this paper. The asphaltene contents in one kinds asphalt was higher than another asphalt. Two kinds polymers modifier were thermoelastomer such as SBS and thermoresin modifier. The thermoresin included low density polyethylene and maleic anhyride graft polyethylene and glycidyl methyacrylate graft polyethylene. The performances of different modified asphalts were analysised and demonstrated by altering base asphalt and SBS species,the SBS content, respectively.The results showed the modified agent could be evenly dispersed in asphalt by twin-screw extruder and the properties of modified asphalt were developed. Two kinds aspahlts were modified by SBS and the softening points were enhenced and the penetration values were down. The ductility was up and down with the SBS content increasing .The softening points and ductily values of R-SBS modified asphalt were bigger than those of L-SBS modified asphalt. The storage performance in high temperature of SBS modified asphalt was better by using stability agent when the SBS content was low. The performances of modified asphalt were best when stability agent content was 0.6%-0.8%.The morphologies of SBS modified asphalt showed that the SBS particles were fine and the particles were dispersed evenly in asphalt for the strong shear force of twin screw extruder. And the SBS particles were dispersing phase and the asphalt was continuous phase in multiphase system. Little polymer molecular bonds had broken and the macromolecular radical was produced for the stability agents exitence, so the chemical reaction had happened between the SBS and asphalt in FTIR result.The changing performances of modified asphalt by physical methods and chemical methods respectively were studied. The FTIRs results showed no reactions had bappened between the asphalt and LDPE in LDPE modified asphalt system and the polymer had been swollen . The absorbing peak in 906cm-1 which was belonged to epoxy group was disappear in FTIR of GMA-g-LDPE modified asphalt. So the paper deduced the reaction had happened between the GMA-g-LDPE and aspahlt in GMA-g-LDPE modified asphalt system. The absorbing peak of anhydride in MAH-g-LDPE modified asphalt was disappear in FTIRs results which demonstrated the reaction had happened between the MAH-g-LDPE and aspahlt. So the paper thought that the ways of MAH-g-LDPE and GMA-g-LDPE modified asphalt belonged to chemical methods for forming chemical link.The reaction happened between functional group in modified polyethylene and asphalt and the chemical bonds had been formed,which had been thought as chemical methods modified asphalt. And polyethylene modified asphalt were thought as physical methods. Softing points of MAH-g-LDPE and GMA-g-LDPE modified asphalt were improved largely by chemical methods compared to LDPE modified asphalt and the temperature sensitivity was reduced. The high temperature performances of modified asphalt were enhenced largely by chemical modified methods which were demonstrated by softening points values and dynamic shear rheometer test. The temperature sensitivity of modified asphalt was lower. the softening point were promoted obviously for high content asphaltene in asphalt when the modified LDPE content were high. The ductility test in low temperature and bending beam rheometer test showed the performances in low temperature of GMA-g-LDPE modified asphalt were not decreased and promoted while the performances of LDPE modifed asphalt and MAH-g-LDPE modifed asphalt decreased largely. The stability performances in high temperature of GMA-g-LDPE modified asphalt was better. The particles of MAH-g-LDPE and LDPE in modified asphalt systems were not evenly and the boundery between the polymer particles and asphalt was obviously in observing microsurface experiment, which indicted the stability performances were worse. There were many bigger particles in continuouse phase whch showed the crosslink had happened in polymer extruding process. And the particle of GMA-g-LDPE were evenly and the boundery between the polymer and asphalt which showed the better comodified Asphaltbility between the polymer and asphalt.