Modified Macromolecular As Cationic Emulsifier For The Manufacture Of Asphalt Emulsion

With the significant development of the transportation system,the problems of maintenance and repair road have been paid more and more attention.Cationic asphalt emulsion has been widely used in the field of road construction due to low operating temperature,low VOCs,low cost,and excellent adhesion.And the key point that determined quality of asphalt emulsion was the asphalt emulsifier.Therefore,the designing and synthesizing novel cationic emulsifiers has been a hotspot of high-performance asphalt emulsion.In this paper,a quaternary ammonium salt intermediate with the epoxy group was synthesized,which was used to modify two natural biopolymers.Then two modified macromolecular emulsifiers were synthesized,and the product’s structure was characterized by FT-IR and ¹H-NMR spectra.The thermal stability of biopolymers before and after modification was characterized by TGA.The surface tension of emulsifier solution was measured by Wilhelmy method,and the effect of temperature and p H on the surface activity of emulsifier was investigated.The droplet size,Zeta potential,apparent viscosity and stability of asphalt emulsion stabilized by modified biopolymer were measured.Moreover,the industrial parameters of asphalt emulsion were determined based on the industrial test regulation.Firstly,the 2,3-epoxypropyldimethylcotadecylammonium chloride（M）was synthesized by epichlorohydrin and N,N-dimethyloctadecylamine.Then,the cationic asphalt emulsifier modified chitosan（MCTS）was synthesized by modification of chitosan with M.The results of measurement of surface activity indicated that the emulsifier has excellent surface activity,and the cmc,andγ_cmc of MCTS decreased as the temperature of solution increased.The asphalt emulsions stabilized by MCTS present dark brown and uniform texture which suggested MCTS has exceedingly good emulsification effect for asphalt.The droplet size of asphalt emulsions ranges from 1.4μm to 2.4μm,and Zeta potential of asphalt emulsion was higher than+30 m V.The cationically modified HEC（CMHEC）was synthesized by introducing the intermediate M into the HEC.The results of surface activity indicated that the surface activity of CMHEC ascended with the p H of aqueous solution descended.The CMHEC has an excellent ability to emulsifying in the manufacture of asphalt emulsion,and the asphalt emulsion presents uniform texture with 0.2wt%CMHEC.The droplet size of emulsion decreases as concentration of CMHEC increases,but the apparent viscosity and stability increase.With the p H of solution ranges from 5 to 1,the droplet size and apparent viscosity decrease firstly and then increase,whereas the Zeta potential present opposite tendency.Moreover,the stability of emulsion is jointly affected by droplet size,viscosity,and Zeta potential.