Epoxy-based composites containing montmorillonite(MMT)modified by silylation reaction withγ-aminopropyltriethoxysilane(γ-APTES)and 3-(glycidyloxypropyl)trimethoxysilane(GPTMS)are successfully prepared.The effects of...Epoxy-based composites containing montmorillonite(MMT)modified by silylation reaction withγ-aminopropyltriethoxysilane(γ-APTES)and 3-(glycidyloxypropyl)trimethoxysilane(GPTMS)are successfully prepared.The effects of filler loading and surface modification on the electrical and thermal properties of the epoxy/MMT composites are investigated.Compared with the pure epoxy resin,the epoxy/MMT composite,whether MMT is surface-treated or not,shows low dielectric permittivity,low dielectric loss,and enhanced dielectric strength.The MMT in the epoxy/MMT composite also influences the thermal properties of the composite by improving the thermal conductivity and stability.Surface functionalization of MMT not only conduces to the better dispersion of the nanoparticles,but also significantly affects the electric and thermal properties of the hybrid by influencing the interfaces between MMT and epoxy resin.Improved interfaces are good for enhancing the electric and thermal properties of nanocomposites.What is more,the MMT modified with GPTMS rather thanγ-APTES is found to have greater influence on improving the interface between the MMT filler and polymer matrices,thus resulting in lower dielectric loss,lower electric conductivity,higher breakdown strength,lower thermal conductivity,and higher thermal stability.展开更多
The exploration of lightweight and efficient electromagnetic wave(EMW)absorption materials is a crucial focus topic because the human body and precision instruments are exposed to the increasingly serious electromagne...The exploration of lightweight and efficient electromagnetic wave(EMW)absorption materials is a crucial focus topic because the human body and precision instruments are exposed to the increasingly serious electromagnetic pollution.Ferrite,as the first type of EMW absorption material,is still the indelible superstar in the EMW absorption field due to its unique double loss mechanism,controllable morphology and high permeability.This review briefly introduces the EMW absorption and attenuation mechanism of ferrite-based composite absorbers,including dielectric loss dominated by charge transfer and polarization relaxation,and magnetic loss consisted of eddy current and resonance.Moreover,we comb the advances in synthesis of ferrite materials.In particular,this paper summarizes the advantages and defects of pure ferrite as EMW absorption material.And the approach to tackling the imbalance of impedance matching and highdensity in ferrite is also reviewed,including ion substitution,design of micro-morphology and doping with dielectric loss materials.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.21806129,51872238,51407134,and 51521065)the China Postdoctoral Science Foundation(Grant No.2016M590619)+3 种基金the Natural Science Foundation of Shandong Province,China(Grant No.ZR2016EEQ28)the State Key Laboratory of Electrical Insulation and Power Equipment,China(Grant No.EIPE14107)the Fundamental Research Funds for the Central Universities,China(Grant No.3102018zy045)the Natural Science Basic Research Plan in Shaanxi Province,China(Grant No.2017JQ5116)
文摘Epoxy-based composites containing montmorillonite(MMT)modified by silylation reaction withγ-aminopropyltriethoxysilane(γ-APTES)and 3-(glycidyloxypropyl)trimethoxysilane(GPTMS)are successfully prepared.The effects of filler loading and surface modification on the electrical and thermal properties of the epoxy/MMT composites are investigated.Compared with the pure epoxy resin,the epoxy/MMT composite,whether MMT is surface-treated or not,shows low dielectric permittivity,low dielectric loss,and enhanced dielectric strength.The MMT in the epoxy/MMT composite also influences the thermal properties of the composite by improving the thermal conductivity and stability.Surface functionalization of MMT not only conduces to the better dispersion of the nanoparticles,but also significantly affects the electric and thermal properties of the hybrid by influencing the interfaces between MMT and epoxy resin.Improved interfaces are good for enhancing the electric and thermal properties of nanocomposites.What is more,the MMT modified with GPTMS rather thanγ-APTES is found to have greater influence on improving the interface between the MMT filler and polymer matrices,thus resulting in lower dielectric loss,lower electric conductivity,higher breakdown strength,lower thermal conductivity,and higher thermal stability.
基金financially supported by the National Natural Science Foundation of China(Nos.52074227,51801186 and U1806219)the Fundamental Research Funds for the Central Universities(No.310201911cx019)。
文摘The exploration of lightweight and efficient electromagnetic wave(EMW)absorption materials is a crucial focus topic because the human body and precision instruments are exposed to the increasingly serious electromagnetic pollution.Ferrite,as the first type of EMW absorption material,is still the indelible superstar in the EMW absorption field due to its unique double loss mechanism,controllable morphology and high permeability.This review briefly introduces the EMW absorption and attenuation mechanism of ferrite-based composite absorbers,including dielectric loss dominated by charge transfer and polarization relaxation,and magnetic loss consisted of eddy current and resonance.Moreover,we comb the advances in synthesis of ferrite materials.In particular,this paper summarizes the advantages and defects of pure ferrite as EMW absorption material.And the approach to tackling the imbalance of impedance matching and highdensity in ferrite is also reviewed,including ion substitution,design of micro-morphology and doping with dielectric loss materials.
