Modification Of Waste Rubber Powder And Its Application In Rubber And Asphalt

The problem of waste tire disposal caused by the dramatic increase of automobile consumption has attracted more and more attention.It is a clean way integrating environmental protection and resource reuse to recycle waste tire products by producing waste rubber powder.The waste rubber powder?RP?prepared by wet method was applied to natural rubber?NR?,and the RP/NR composites with excellent properties were obtained by improving the interfacial bonding between the two materials.On the other hand,the application of RP to road asphalt has been studied to improve the compatibility of RP and asphalt,thereby improving the high and low temperature resistance of asphalt by utilizing the properties of RP elastomer,which has significant social and economic value.This paper mainly studies how to improve the interfacial bond between RP and Rubber matrix,asphalt matrix through the modification of RP.This thesis mainly studies how to improve the interfacial adhesion between RP and rubber and asphalt by RP modification,and prepare RP/NR composites and RP modified rubber asphalt materials with excellent performance,and explored the relationship between the modification mechanism and the structure and properties of the materials.It includes mechanochemical modification of RP and its application in natural rubber?NR?,and the application of mechanochemical modification,graft modification of RP in asphalt.In this thesis,the waste rubber powder is mechanochemical modified by modifier AH and high shearing via twin-screw extruder,and applied it to natural rubber?NR?.The modification effects and mechanism of unmodified waste rubber powder?RP?,chemically modified waste rubber powder?CRP?,mechanically modified waste rubber powder?MRP?and mechanochemical waste rubber powder?MCRP?were compared and analyzed.Compared with RP,the surface activity of MRP and MCRP increased and the crosslinking density decreased,while the surface activity and degradation effect of CRP were not obvious,and the modification effect of MCRP was the best.The structure and properties of RP/NR,CRP/NR,MRP/NR and MCRP/NR materials prepared from modified waste rubber powder were characterized and analyzed.The results of RPA test showed that the processability of MCRP/NR blends was the best,the composite modulus of vulcanized blends was the highest,and the loss factor was the lowest.Compared with RP,CRP,MRP and MCRP have better dispersion and interface bonding in NR.DSC confined molecular layer analysis showed that the mass fraction of confined molecular layer(?_im)of MCRP and NR was the largest,and the interaction force between MCRP and NR was the strongest.MCRP/NR composite rubber has the best comprehensive properties,and the best modification process of waste rubber powder is extrusion temperature 100?,Modifier AH dosage 3 phr.Compared with RP/NR,the tensile strength and elongation at break of waste rubber powder prepared by the optimum modification process and NR compound rubber increased by 31%and 107%respectively.Secondly,the application of wet and normal temperature waste rubber powder?RP? in asphalt was compared,and the RP was modified by mechanochemical and grafting technology.The modified mechanism of rubber asphalt was analyzed by SEM,TGA,FTIR and rheological analysis.It was found that the properties of rubber asphalt prepared by wet waste rubber powder were better than those of rubber asphalt prepared by normal temperature waste rubber powder,such as high and low temperature resistance,dispersion resistance,aging resistance and thermal stability.Grafting modified waste rubber powder?GRP?can effectively improve the cracking resistance at low temperature and temperature sensitivity of asphalt,and reduce the construction viscosity of rubber asphalt at high temperature,but the high temperature performance decreases,and the quality loss increases after aging,while the penetration ratio at25?is obviously improved,and the dispersion of GRP in asphalt is better than RP,and the interfacial bonding becomes stronger.The mechanochemical modified waste rubber powder?MCRP?can effectively improve the softening point of the modified asphalt,the 5°C ductility,the aging 25°C penetration,the 25°C penetration ratio and the 175°C viscosity.The quality loss of MCRP/asphalt increased after aging,and the rubber asphalt prepared by extrusion-modified waste rubber powder at 120°C and 140°C had the best comprehensive performance.Compared with GRP and MCRP,the overall performance of MCRP/asphalt is better,and the low temperature performance of GRP/asphalt is more prominent.