The fracture toughness of carbon fiber reinforced epoxy composite(CFRP)was investigated through mode I and mode II shaped fracture system in this paper.A novel polyimide with trifluoromethyl groups and grafted nanosil...The fracture toughness of carbon fiber reinforced epoxy composite(CFRP)was investigated through mode I and mode II shaped fracture system in this paper.A novel polyimide with trifluoromethyl groups and grafted nanosilica were used to modify epoxy resin.Effect of modified resin and unmodified resin on fracture toughness of CFRP was compared and discussed.Lay-up angles and thicknesses effects on fracture toughness of composites were also investigated.The fracture toughness of CFRP was obtained through double cantilever beam(DCB)and end notched flexure(ENF)tests.The results showed that the composites prepared by modified resin exhibited high fracture toughness compared with unmodified composites.The fracture toughness value of mode I increased from 1.83 kJ/m2 to 4.55 kJ/m2.The fracture toughness value of mode II increased from 2.30 kJ/m2 to 6.47 kJ/m2.展开更多
Lead halide perovskites have been demonstrated as multifunctional materials.Herein,we demonstrate the tunable thermotropic phase transitions and optical bandgap,together with large dielectric response and superionic c...Lead halide perovskites have been demonstrated as multifunctional materials.Herein,we demonstrate the tunable thermotropic phase transitions and optical bandgap,together with large dielectric response and superionic conduction through mixed halogen anion modification in a family of bromide-iodide lead halide perovskites[Et_(3)PrN][PbI_(x)Br_(3-x)](Et_(3)PrN^(+)=triethylpropylammonium and x=0,1.08,1.83,2.50 and 3;labeled as 1-5 sequentially).All members in this family are isomorphic at room temperature,crystallizing in the monoclinic space group P2_(1)/n or P2_(1)/c,and undergo a phase transition above 440 K.DSC revealed a phase transition that is relevant to the order-to-disorder transformations of globular-shaped cations.Significantly,the lead halide perovskites exhibit superionic conduction beyond 10^(-3) S cm^(-1) in the high-temperature(HT)phase.This study provides an efficient strategy for design of multifunctional lead halide perovskites.展开更多
基金National Natural Science Foundation of China(No.11802192)Natural Science Foundation of Jiangsu Province,China(No.BK20180244)Nantong Science and Technology Project,China(No.JC2019012)。
文摘The fracture toughness of carbon fiber reinforced epoxy composite(CFRP)was investigated through mode I and mode II shaped fracture system in this paper.A novel polyimide with trifluoromethyl groups and grafted nanosilica were used to modify epoxy resin.Effect of modified resin and unmodified resin on fracture toughness of CFRP was compared and discussed.Lay-up angles and thicknesses effects on fracture toughness of composites were also investigated.The fracture toughness of CFRP was obtained through double cantilever beam(DCB)and end notched flexure(ENF)tests.The results showed that the composites prepared by modified resin exhibited high fracture toughness compared with unmodified composites.The fracture toughness value of mode I increased from 1.83 kJ/m2 to 4.55 kJ/m2.The fracture toughness value of mode II increased from 2.30 kJ/m2 to 6.47 kJ/m2.
基金financially supported by Priority Academic Program Development of Jiangsu Higher Education Institutions,National Natural Science Foundation of China(Grant No.22073047 and 22101131)Natural Science Foundation of Jiangsu Province(Grant No.BK20210543).
文摘Lead halide perovskites have been demonstrated as multifunctional materials.Herein,we demonstrate the tunable thermotropic phase transitions and optical bandgap,together with large dielectric response and superionic conduction through mixed halogen anion modification in a family of bromide-iodide lead halide perovskites[Et_(3)PrN][PbI_(x)Br_(3-x)](Et_(3)PrN^(+)=triethylpropylammonium and x=0,1.08,1.83,2.50 and 3;labeled as 1-5 sequentially).All members in this family are isomorphic at room temperature,crystallizing in the monoclinic space group P2_(1)/n or P2_(1)/c,and undergo a phase transition above 440 K.DSC revealed a phase transition that is relevant to the order-to-disorder transformations of globular-shaped cations.Significantly,the lead halide perovskites exhibit superionic conduction beyond 10^(-3) S cm^(-1) in the high-temperature(HT)phase.This study provides an efficient strategy for design of multifunctional lead halide perovskites.
