Study On The Hydrophobic Treatment Of Lignin And The Performance Of Modified Asphalt

Lignin is a rich bio-based renewable resource.Using lignin for asphalt modification can not only improve the utilization rate of asphalt and lignin,but also improve the performance of asphalt materials.In this paper,the average molecular structure formula of lignin was constructed by analyzing the structural parameters of lignin,and molecular dynamics simulation was carried out using Gromacs.The theoretical research was focused on the dispersion of organic solvent lignin(OL)and esterified hydrophobic modified lignin in asphalt,intermolecular bonding strength,system stability,etc.Based on the simulation analysis results,the OL was esterified and acetylated hydrophobic modified,and its morphology,functional groups The thermal properties were characterized and analyzed,and the modification conditions of asphalt were optimized and the performance of modified asphalt was analyzed.The research results are as follows:(1)The binding energy between asphalt molecules is-12172.44 kJ/mol,and the binding energy after adding organic lignin and esterified organic lignin is-15443.41 kJ/mol and-15635.51 kJ/mol,respectively.The binding energy between asphalt molecules increases by 26.87% and 28.45%,respectively.The binding energy between asphalt molecule and organic lignin molecule and esterified organic lignin molecule is-2748.1972 kJ/mol and-3711.8533 kJ/mol respectively,and the binding energy is increased by 35.06%.In addition,the number of hydrogen bonds,density distribution,diffusion coefficient,radial distribution function and other relevant parameters confirmed the theoretical feasibility of organic lignin modified asphalt and the more uniform distribution of hydrophobic esterified organic lignin in asphalt.(2)The hydrophobic modification of organic lignin was carried out with lauroyl chloride and acetic anhydride as raw materials respectively at 80℃.The optimal yields of the two methods were 42.26% and 53.65% respectively after 2 h and 24 h.The hydrophobicity of lignin treated with esterification and acetylation became stronger,with water contact angles of 118.40° and 130.87°,respectively,higher than that of organic lignin at 68.04°.After modification,the thermal properties of organic lignin change,and the overall thermal stability is acetylated lignin>organic solvent lignin>esterified lignin.(3)With the increase of organic lignin doping,the penetration and ductility of asphalt decrease,and the softening point increases,indicating that the hightemperature stability of modified asphalt is enhanced while the low-temperature crack resistance decreases.When the doping amount of organic lignin increases from 0% to10%,the penetration rate decreases from 85(0.1 mm)to 60(0.1 mm),the softening point increases from 67.5℃ to 75℃,and the ductility decreases from 125 cm to 55 cm.Obtaining viscosity temperature relationship,complex shear modulus G*,phase angle through high and low temperature performance testing δ As well as parameters such as low-temperature brittleness point,stiffness modulus,and creep rate,it was found that organic solvent lignin exhibits good high-temperature performance,but there still exits space for improvement in changing the low-temperature performance of asphalt.