Epoxy resin,characterized by prominent mechanical and electric-insulation properties,is the preferred material for packaging power electronic devices.Unfortunately,the efficient recycling and reuse of epoxy materials ...Epoxy resin,characterized by prominent mechanical and electric-insulation properties,is the preferred material for packaging power electronic devices.Unfortunately,the efficient recycling and reuse of epoxy materials with thermally cross-linked molecular structures has become a daunting challenge.Here,we propose an economical and operable recycling strategy to regenerate waste epoxy resin into a high-performance material.Different particle size of waste epoxy micro-spheres(100–600μm)with core-shell structure is obtained through simple mechanical crushing and boron nitride surface treatment.By using smattering epoxy monomer as an adhesive,an eco-friendly composite material with a“brick-wall structure”can be formed.The continuous boron nitride pathway with efficient thermal conductivity endows eco-friendly composite materials with a preeminent thermal conductivity of 3.71 W m^(−1)K^(−1)at a low content of 8.5 vol%h-BN,superior to pure epoxy resin(0.21 W m^(−1)K^(−1)).The composite,after secondary recycling and reuse,still maintains a thermal conductivity of 2.12 W m^(−1)K^(−1)and has mechanical and insulation properties comparable to the new epoxy resin(energy storage modulus of 2326.3 MPa and breakdown strength of 40.18 kV mm^(−1)).This strategy expands the sustainable application prospects of thermosetting polymers,offering extremely high economic and environmental value.展开更多
The importance of geometrical control of three dimensional(3D)printable concrete without the support of formwork is widely acknowledged.In this study,a numerical model based on computational fluid dynamics was develop...The importance of geometrical control of three dimensional(3D)printable concrete without the support of formwork is widely acknowledged.In this study,a numerical model based on computational fluid dynamics was developed to evaluate the geometrical quality of a 3D printed layer.The numerical results were compared,using image analysis,with physical cross-sectional sawn samples.The influence of printing parameters(printing speed,nozzle height,and nozzle diameter)and the rheological behavior of printed materials(yield stress),on the geometrical quality of one printed layer was investigated.In addition,the yield zone of the printed layer was analyzed,giving insights on the critical factors for geometrical control in 3D concrete printing.Results indicated that the developed model can precisely describe the extrusion process,as well as the cross-sectional quality.展开更多
基金supported by the National Natural Science Foundation of China(Nos.51977084 and 52307025).
文摘Epoxy resin,characterized by prominent mechanical and electric-insulation properties,is the preferred material for packaging power electronic devices.Unfortunately,the efficient recycling and reuse of epoxy materials with thermally cross-linked molecular structures has become a daunting challenge.Here,we propose an economical and operable recycling strategy to regenerate waste epoxy resin into a high-performance material.Different particle size of waste epoxy micro-spheres(100–600μm)with core-shell structure is obtained through simple mechanical crushing and boron nitride surface treatment.By using smattering epoxy monomer as an adhesive,an eco-friendly composite material with a“brick-wall structure”can be formed.The continuous boron nitride pathway with efficient thermal conductivity endows eco-friendly composite materials with a preeminent thermal conductivity of 3.71 W m^(−1)K^(−1)at a low content of 8.5 vol%h-BN,superior to pure epoxy resin(0.21 W m^(−1)K^(−1)).The composite,after secondary recycling and reuse,still maintains a thermal conductivity of 2.12 W m^(−1)K^(−1)and has mechanical and insulation properties comparable to the new epoxy resin(energy storage modulus of 2326.3 MPa and breakdown strength of 40.18 kV mm^(−1)).This strategy expands the sustainable application prospects of thermosetting polymers,offering extremely high economic and environmental value.
基金the National Natural Science Foundation of China(Grant No.52008224)the Open Fund of innovation institute for Sustainable Maritime Architecture Research and Technology(iSMART),Qingdao University of Technology(No.2020-031)+1 种基金the Key Technology Research and Development Program of Shandong(No.2019GSF110004)the financial support received from the Industrial Research Fund(IOF.PRO.2022.0010.01)from Ghent University.
文摘The importance of geometrical control of three dimensional(3D)printable concrete without the support of formwork is widely acknowledged.In this study,a numerical model based on computational fluid dynamics was developed to evaluate the geometrical quality of a 3D printed layer.The numerical results were compared,using image analysis,with physical cross-sectional sawn samples.The influence of printing parameters(printing speed,nozzle height,and nozzle diameter)and the rheological behavior of printed materials(yield stress),on the geometrical quality of one printed layer was investigated.In addition,the yield zone of the printed layer was analyzed,giving insights on the critical factors for geometrical control in 3D concrete printing.Results indicated that the developed model can precisely describe the extrusion process,as well as the cross-sectional quality.
