Research On The Modification And The Microstructure Of The Asphalt Modified By Packaging Thermoplastic Polymer

Thermoplastic polymers played an important role in packaging of merchandise.But these materials were discarded as waste after losing their original functions.This condition resulted in not only environmental pollutions but also huge wastes of resources.In order to solve the environmental problems efficiently,it was a burning issue to study how to develop the recycling technology of reusing the wasted thermoplastic polymer packaging.Besides,due to the large demand of high-performance asphalt materials,China has become a big consumer on the modified asphalt in the world.The demand on fast and efficient logistics and traffics had provided a broad developing space for the application and research of high-performance modified asphalt.However,the fierce competition of markets made the research on modified asphalt mostly base on the commercial purposes.So there were rare researches on modification mechanism and micro-structure of asphalt and there was no clear conclusion.In this study,instead of ordinary polymer modifiers,the waste packaging thermoplastic polymers(WPE and WEVA)were used to modify the paving asphalt as main modifiers.First,the relationship between the compatibility and the performance of modified asphalt was studied from the structure of four components of the asphalt.Second,the waste PAN carbon fibers and the nano materials of graphene oxide were used to reinforce the compatibility of modified asphalt via two different technology sections.The relationship between the compatibility and the thermal stability and the aging resistance was studied through the changes on the structure of modified asphalt.The mechanism of modification was revealed by the pictures of micro and macro.These provided a theoretical basis for the high-value utilization of waste polymer and the preparing of modified asphalt with high performance.The study on the modification of the asphalt modified by waste thermoplastic packaging polymer showed that the comprehensive performance of the asphalt modified by WPE was optimal,on the condition of such as the ratio of WPE was about 4%,the modification temperature was about 170 ?,the shear rate was 3900 r/min,and the modification time control in 60-100 min.It was found by studying the asphalt modified by WPE through the correlation analysis on the four components and the performance of modified asphalt that the modification was physical modification.Along with the increase of WPE,the asphaltene and resin in four components of the asphalt increased,while the saturate reduced,and the aromatics remains the same.WPE has a good compatibility with saturate and aromatics of the light component,but poor compatibility with asphaltene and resin.The performance of modified asphalt at high temperature was proportional to the content of asphaltene and resin which decided the high temperature performance of asphalt.In”asphaltene micelle" and "polymer micelle" model system of the modified asphalt,aromatics and saturate as benign solvent were the key determinant on the compatibility of the modified asphalt.PAN-carbon fibers were used to reinforce the compatibility of the asphalt modified by WPE.The carbon fibers had a good adsorption to WPE due to the uneven layer and roughness treated polar group on the surface of carbon fibers.The formed thorns adsorption mode enhanced the swelling and adsorption of WPE to the lightweight components of modified asphalt,which improved the compatibility of the asphalt system.The excellent compatibility could enhance the thermal stability and aging resistance.In the asphalt composite modified by WPE and carbon fibers,with the increase of the carbon fibers,the thermal decomposition temperature of the modified asphalt rose gradually and the heat loss in the same temperature gradually reduced.In all,the high temperature performance and deformation resistance has dramatically improved.Two kinds of modifier preparation,which were the molten co-extrusion and the dissolve and flocculation,could better improve the thermal stability of the composite modified asphalt.And the asphalt modified by the modifiers prepared by molten co-extrusion method had the best performance.The carbon fibers could improve the compatibility of the composite modified asphalt by reducing the damage of the asphalt system balance,and improve aging resistance by reducing the oxidation of lightweight components.The thermal decomposition temperature of aging asphalt raised with the increase of the carbon fibers,but the thermal decomposition temperature of the aging modified asphalt with the content of carbon fibers of 0.12%become low.The content of carbon fibers should not be more than 0.1%.Excessive carbon fibers itself will occur aggregation,which affect the balance of the asphalt system and reduce the anti-aging performance.Graphene oxide were used to reinforce the compatibility of the asphalt composite modified by WEVA.Graphene oxide as nanoscale particles could disperse in the micron scale particles of WEVA.The dispersion could reduce the surface free energy of graphene oxide and WEVA,inhibite aggregation of WEVA,prevente the floatation and separation of WEVA,improve the compatibility and comprehensive performance of modified asphalt.The advisable content of graphene oxide in composite modified asphalt was 0.08%-0.1%.Excessive graphene oxide not only increased the complexity of the asphalt modification,but also affected the performance of the modified asphalt at high and low temperature.The solubility between the graphene oxide dispersed in the asphalt and the asphalt components was very difference,so the asphalt system did not form the long-term stability in the storage at high temperature.Based on a large number of experimental studies,the modification of the asphalt modified by the waste packaging thermoplastic polymers and the modification mechanism were studied from the microstructure of asphalt components.FT-IR spectrums of the asphalt modified by thermoplastic polymer and by carbon fiber or graphene oxide and thermoplastic polymer all showed that of the thermoplastic polymer particles and the formation of the network structure of the thermthe modification were physical modification.In the modification,the dispersion and swelling oplastic polymers were the key to improve the compatibility of asphalt components and the comprehensive performance of modified asphalt.