Study On The Performance And Mechanism Of Bio-asphalt Prepared By Synthetic Wood Resin From Straw Liquefaction Product

Petroleum is a non-renewable resource,and its declining reserves will cause the road petroleum asphalt to be in short supply for a long time.In the context of advocating greenness,environmental protection and sustainable development,it is urgent to find an alternative material for petroleum asphalt.Recently the application technology of biomass energy,which has received much attention,is considered to be the most potential choice to solve this problem.Combining the current situation of abundant agroforestry waste reserves and low recycling rate in China,this paper prepares bio-asphalt based on the thermochemical liquefaction and resinization technology of rice straw,hoping to accumulate theoretical and practical experience for the research and development of new pavement materials.First,the rice straw and its main components(cellulose and lignin)were subjected to thermochemical liquefaction at different times,and the liquefaction reaction process was explored by means of separation and purification of liquefied products,thermogravimetric testing and infrared spectroscopy analysis: The straw and its main components undergo liquefaction(degradation,hydrolysis,etc.)and polycondensation reactions(phenolization,carbonization,etc.)simultaneously in phenol-polyol solutions.Low-molecular-weight compounds rich in polar groups are formed,and a certain proportion of biochar residue remains under the combined action of the two reactions.In comparison,the liquefaction of cellulose is more difficult,and the liquefaction effect of straw is greatly affected by its content.The liquefied products have similar chemical composition,non-Newtonian flow behavior and lower viscosity compared with asphalt materials.However,its hydrophobicity and thermal stability need to be further improved.Secondly,Box-Behnken response surface design was used to study the synthesis control of wood resins in order to improve the properties of liquefied products.the optimal synthesis process was optimized by taking resin yield and viscosity at 135°C as response indexes.Based on this,pure phenol and three liquefied products(with different liquefaction solvents)were used as raw materials to prepare wood resin,and the resinification conversion mechanism of liquefied products was explored through the analysis of the physical and chemical properties of the resinous products.The results showed that the phenol liquefaction product and the phenol-polyol mixed liquefaction product can partially replace phenol as a raw material to synthesize ortho-substituted thermoplastic phenolic resins through addition and polycondensation reaction with formaldehyde.However,the polyol liquefaction product doesn’t show potential.the synthesized phenolic resin and two wood resins both have a higher molecular weight and better thermal stability than the liquefaction product.Finally,in view of the similarity between wood resin and asphalt materials,it was fused with base asphalt in different proportions to prepare bio-asphalt.And the feasibility of partial replacement of asphalt with wood resin was evaluated from the aspects of rheological properties,temperature sensitivity and cohesive properties: The performance of bio-asphalt is greatly affected by the selected reagents during the straw liquefaction.In comparison,the bio-asphalt containing the resin synthesized by the mixed liquefaction product has more excellent comprehensive performance.the content of no more than 50% is acceptable under the premise of not weakening the pavement performance of the base asphalt.The results of thermogravimetric test and infrared analysis showed that: Complex physical and chemical reactions will occur during the fusion process.The content of aromatic compounds in the bio-asphalt will increase.The wood resin and the base asphalt may be connected by ether bonds(aromatic ethers and fatty ethers)to form a stable and uniform blending system.