Polyether ether ketone(PEEK)has good mechanical properties.However,its high viscosity when molten limits its use because it is hard to process.PEEK nanocomposites containing both carbon nanotubes(CNTs)and polyether im...Polyether ether ketone(PEEK)has good mechanical properties.However,its high viscosity when molten limits its use because it is hard to process.PEEK nanocomposites containing both carbon nanotubes(CNTs)and polyether imide(PEI)were pre-pared by a direct wet powder blending method using a vertical injection molding machine.The addition of an optimum amount of PEI lowered the viscosity of the molten PEEK by approximately 50%while producing an increase in the toughness of the nanocom-posites,whose strain to failure increased by 129%,and fracture energy increased by 97%.The uniformly dispersed CNT/PEI powder reduced the processing difficulty of PEEK nanocomposites without affecting the thermal resistance.This improvement of the strength and viscosity of PEEK facilitate its use in the preparation of thermoplastic composites.展开更多
In view of the mechanics characteristic of cemented tailings backfill(CTB)at early age,the separation Hopkinson pressure bar test device was used to explore the effects of curing age and impact energy.A total of 48 CT...In view of the mechanics characteristic of cemented tailings backfill(CTB)at early age,the separation Hopkinson pressure bar test device was used to explore the effects of curing age and impact energy.A total of 48 CTB samples with diameter of 50 mm and length of 25 mm were prepared with curing ages of 3,5,7 and 9 d.Impact tests under different impact energy(10,20,30 and 40 J)were carried out.The microstructure of CTB at different ages was analyzed by scanning electron microscopy(SEM).The results show that,the curing age mainly affects the mechanical properties and internal structure of early-age CTB.With increasing curing age,the mechanical properties of early-age CTB change from viscoelasticity to brittleness.The impact energy mainly affects the response of dynamic peak compressive strength to strain rate.Under low strain rate,the structure of CTB is broken,but still has bearing capacity,affecting the formation of later strength.It is concluded that the structural loses completely under the action of high strain rate.Therefore,the control of impact energy and the protection of curing age should be fully considered in actual production process.展开更多
文摘Polyether ether ketone(PEEK)has good mechanical properties.However,its high viscosity when molten limits its use because it is hard to process.PEEK nanocomposites containing both carbon nanotubes(CNTs)and polyether imide(PEI)were pre-pared by a direct wet powder blending method using a vertical injection molding machine.The addition of an optimum amount of PEI lowered the viscosity of the molten PEEK by approximately 50%while producing an increase in the toughness of the nanocom-posites,whose strain to failure increased by 129%,and fracture energy increased by 97%.The uniformly dispersed CNT/PEI powder reduced the processing difficulty of PEEK nanocomposites without affecting the thermal resistance.This improvement of the strength and viscosity of PEEK facilitate its use in the preparation of thermoplastic composites.
基金Project(CXZZBS2019126)supported by the Innovative Support Program for Doctoral Students in Hebei Province,ChinaProject(QN2019078)supported by the Science and Technology Research Project of Colleges and University in Hebei Province,ChinaProject(51774137)supported by the National Natural Science Foundation of China。
文摘In view of the mechanics characteristic of cemented tailings backfill(CTB)at early age,the separation Hopkinson pressure bar test device was used to explore the effects of curing age and impact energy.A total of 48 CTB samples with diameter of 50 mm and length of 25 mm were prepared with curing ages of 3,5,7 and 9 d.Impact tests under different impact energy(10,20,30 and 40 J)were carried out.The microstructure of CTB at different ages was analyzed by scanning electron microscopy(SEM).The results show that,the curing age mainly affects the mechanical properties and internal structure of early-age CTB.With increasing curing age,the mechanical properties of early-age CTB change from viscoelasticity to brittleness.The impact energy mainly affects the response of dynamic peak compressive strength to strain rate.Under low strain rate,the structure of CTB is broken,but still has bearing capacity,affecting the formation of later strength.It is concluded that the structural loses completely under the action of high strain rate.Therefore,the control of impact energy and the protection of curing age should be fully considered in actual production process.
