Recyclability of thermosetting polymers and their composites is a challenge for alleviating environmental pollution and resource waste.In this study,solvent-recyclable thermosetting polyimide(PI)and its composite were...Recyclability of thermosetting polymers and their composites is a challenge for alleviating environmental pollution and resource waste.In this study,solvent-recyclable thermosetting polyimide(PI)and its composite were successfully synthesized.The tensile strength,elongation at break,and Young’s modulus of PI are 108.70±7.29 MPa,19.35%±3.89%,and 2336.42±128.00 MPa,respectively.The addition of reduced graphene oxide(RGO)not only enhances the mechanical properties of PI but also endows it with excellent tribological properties.The PI illustrates a high recycling efficiency of 94.15%,but the recycled composite exhibits inferior mechanical properties.The recycling and utilization of PI and its composite are realized through imine bonds(-C=N),which provides new guidance for solving the problem of environmental pollution and resource waste and is potential application in the field of sustainable tribology.展开更多
Polytetrafluoroethylene(PTFE)blended with polyimide(PI)and filled with boron nitride(BN)is prepared through cold pressing and sintering for composites with remarkable wear resistance and reduced coefficient of frictio...Polytetrafluoroethylene(PTFE)blended with polyimide(PI)and filled with boron nitride(BN)is prepared through cold pressing and sintering for composites with remarkable wear resistance and reduced coefficient of friction(COF).The characterizations show that BN and PI at different levels,improve the hardness,dynamic thermo-mechanical modulus,thermal conductivity,and tribological properties of PTFE.PI boosts the dispersion and bonding of BN in PTFE.In dry sliding friction of a block-on-ring tribometer,the wear rate and COF of 10:10:80 BN/PI/PTFE reduce to almost 1/300 and 80%of those of pure PTFE,respectively,as the wear mechanism transition from being adhesive to partially abrasive.This occurs only when the additives BN and PI induce a synergistic effect,that is,at concentrations that are not higher than ca.10 wt%and 15 wt%,respectively.The obvious agglomeration at high percentages of added PI and severe conditions(400 N and 400 rpm)induce strong adhesive failure.The variations in the tensile properties,hardness,crystallization,and microstructure of the composites correspond to different effects.The multiple parameters of the plots of wear and friction are transformed into their contour curves.The mechanism transition maps aid in understanding the influence of various test conditions and composite compositions on the contact surfaces in the space-time framework of wear.展开更多
基金financially supported by the Natural Science Foundation of Gansu Province(Grant No.22JR5RA108)the National Natural Science Foundation of China(Grant No.52205234)+1 种基金the Youth Innovation Promotion Association of Chinese Academy of Sciences(Grant No.Y2018457)the Key Program of the Lanzhou Institute of Chemical Physics,CAS(Grant No.KJZLZD-3).
文摘Recyclability of thermosetting polymers and their composites is a challenge for alleviating environmental pollution and resource waste.In this study,solvent-recyclable thermosetting polyimide(PI)and its composite were successfully synthesized.The tensile strength,elongation at break,and Young’s modulus of PI are 108.70±7.29 MPa,19.35%±3.89%,and 2336.42±128.00 MPa,respectively.The addition of reduced graphene oxide(RGO)not only enhances the mechanical properties of PI but also endows it with excellent tribological properties.The PI illustrates a high recycling efficiency of 94.15%,but the recycled composite exhibits inferior mechanical properties.The recycling and utilization of PI and its composite are realized through imine bonds(-C=N),which provides new guidance for solving the problem of environmental pollution and resource waste and is potential application in the field of sustainable tribology.
基金This work was supported by the National Natural Science Foundation of China(No.51073021).
文摘Polytetrafluoroethylene(PTFE)blended with polyimide(PI)and filled with boron nitride(BN)is prepared through cold pressing and sintering for composites with remarkable wear resistance and reduced coefficient of friction(COF).The characterizations show that BN and PI at different levels,improve the hardness,dynamic thermo-mechanical modulus,thermal conductivity,and tribological properties of PTFE.PI boosts the dispersion and bonding of BN in PTFE.In dry sliding friction of a block-on-ring tribometer,the wear rate and COF of 10:10:80 BN/PI/PTFE reduce to almost 1/300 and 80%of those of pure PTFE,respectively,as the wear mechanism transition from being adhesive to partially abrasive.This occurs only when the additives BN and PI induce a synergistic effect,that is,at concentrations that are not higher than ca.10 wt%and 15 wt%,respectively.The obvious agglomeration at high percentages of added PI and severe conditions(400 N and 400 rpm)induce strong adhesive failure.The variations in the tensile properties,hardness,crystallization,and microstructure of the composites correspond to different effects.The multiple parameters of the plots of wear and friction are transformed into their contour curves.The mechanism transition maps aid in understanding the influence of various test conditions and composite compositions on the contact surfaces in the space-time framework of wear.
