A flame retardant containing multiple antiflaming elements usually exhibits high-efficient flame retardancy. Here, a novel P/N/Si-containing ammonium polyphosphate derivative(APTES-APP) is synthesized from ammonium po...A flame retardant containing multiple antiflaming elements usually exhibits high-efficient flame retardancy. Here, a novel P/N/Si-containing ammonium polyphosphate derivative(APTES-APP) is synthesized from ammonium polyphosphate(APP) and silane coupling agent(3-aminopropyl)triethoxysilane(APTES)via cation exchange, which is quite different in the chemical structure from APTES-modified APP for retaining silicon hydroxyls. APTES-APP is highly efficient for the epoxy resin. 8%(mass) APTES-APP imparts excellent flame retardancy to the epoxy resin, with a V-0 rating at the UL-94 test(1.6 mm)and an LOI value of 26%(vol). The peak heat release rate and total smoke production of the flameretardant epoxy resin are decreased by 68.1% and 31.3%, respectively. The synergy of P/N/Si contributes to the well-expanded char residue with a strong and dense surface layer, which is a very good barrier against heat and mass transfer. Besides, there is no significant deterioration in the mechanical properties of flame-retardant epoxy resin thanks to silicon hydroxyls forming hydrogen bonds with epoxy molecules. Meanwhile, other molecules can be grafted onto APTES-APP via these silicon hydroxyls, if needed.Briefly, this work has developed a new strategy for amino silane as flame retardants. In conjunction with a low-cost and simple preparation method, APTES-APP has a promising prospect in the high-performance flame-retardant epoxy.展开更多
A graphene oxide/nano-silica(GOS)hybrid was rapidly and easily synthesized using graphene oxide(GO)and nano-silica(nano-SiO_(2))as raw materials,and the synthesized GOS was used to improve the mechanical properties of...A graphene oxide/nano-silica(GOS)hybrid was rapidly and easily synthesized using graphene oxide(GO)and nano-silica(nano-SiO_(2))as raw materials,and the synthesized GOS was used to improve the mechanical properties of epoxy resin(EP).The modified EP with different mass fractions of GOS(0,0.1%,0.2%,0.3%and 0.4%)were prepared and studied.The structure,thermal stability,mechanical properties,fracture toughness and failure morphology of the modified EP were analyzed.The results showed that the tensile strength of GOS modified EP increased from 40.6 MPa to 80.2 MPa compared with EP,the critical stress intensity factor of GOS modified EP increased by 65.9%from 0.82 MPa·m^(1/2)to 1.36 MPa·m^(1/2),indicating a significant enhancement in fracture toughness.In addition,failure morphology was observed by scanning electron microscopy(SEM)observation.The toughness mechanism of the modified EP was also discussed.Finally,the thermal stability of the modified EP was improved by the addition of GOS.Compared with neat EP,the initial thermal degradation temperature and glass transition temperature of GOS modified EP increased by 4.5℃and 10.3℃,respectively.展开更多
We improved the adhesion between silicon based insulating materials and epoxy resin composites by adding the adhesion promoter cycloborosiloxane(BSi,cyclo-1,3,3,5,7,7-hexaphenyl-1,5-diboro-3,7-disiloxane).The experime...We improved the adhesion between silicon based insulating materials and epoxy resin composites by adding the adhesion promoter cycloborosiloxane(BSi,cyclo-1,3,3,5,7,7-hexaphenyl-1,5-diboro-3,7-disiloxane).The experimental results show that the addition of BSi in the silicone rubber(SR)system significantly increases the tensile shear strength between BSi and epoxy resin(EP),reaching 309%of the original value.On this basis,the mechanism of BSi to enhance the adhesion effect was discussed.The electron deficient B in BSi attracted the electron rich N and O in EP to enhance the chemical interaction,combined with the interfacial migration behavior in the curing process,to improve the adhesion strength.This study provides the design and synthesis ideas of adhesive aids,and a reference for further exploring the interface mechanism of epoxy resin matrix composites.展开更多
In this study,the durability of a new polymer carbonfiber-reinforced epoxy resin used to produce composite material in the aerospacefield is investigated through analysis of the corrosion phenomena occurring at the micr...In this study,the durability of a new polymer carbonfiber-reinforced epoxy resin used to produce composite material in the aerospacefield is investigated through analysis of the corrosion phenomena occurring at the microscopic scale,and the related infrared spectra and thermal properties.It is found that light and heat can con-tribute to the aging process.In particular,the longitudinal tensile strength displays a non-monotonic trend,i.e.,itfirst increases and then decreases over time.By contrast,the longitudinal compressive and inter-laminar shear strengths do not show significant changes.It is also shown that the inter-laminar shear strength of carbonfiber/epoxy resin composites with inter-laminar hybrid structure is better than that of pure carbonfiber materials.The related resistance to corrosion can be improved by more than 41%.展开更多
The mechanical properties of Portland cement differ from the weakly consolidated shallow formation in deep water.This results in undesired abrupt changes in the compressive strength and elastic modulus at the cement–...The mechanical properties of Portland cement differ from the weakly consolidated shallow formation in deep water.This results in undesired abrupt changes in the compressive strength and elastic modulus at the cement–formation interface.In this study,a water-borne epoxy resin was applied as a strengthening material to reinforce the weakly consolidated shallow formation and protect the cement sheath from potential failure.The mechanical properties of the unconsolidated clay were tested,including their changes with increases in the temperature and curing time.In addition,the effects of the seawater,cement slurry alkaline filtrate,and saltwater drilling fluid were evaluated.As confirmed by the results,the strengthening fluid was excellent at reinforcing the unconsolidated clay,with a compressive strength of 2.49 MPa(after curing for 7 days),even at a dosage of 5%.A cement slurry filtrate with a high pH was suitable to produce the required strengthening of the formation,especially its early age strength.It should also be pointed out that the used fluid exhibited good compatibility with the saltwater drilling fluid and seawater behaved well as a diluent for the strengthening fluid.展开更多
Werborne ultrafine particles of epoxy resin were prepared by phase inversion tech-nique. The results of SEM revealed that the particles diameter was in the range of 50to 100 nm and the effects on amount of water requi...Werborne ultrafine particles of epoxy resin were prepared by phase inversion tech-nique. The results of SEM revealed that the particles diameter was in the range of 50to 100 nm and the effects on amount of water required at phase inversion point were alsodisc?d.展开更多
This paper presents a preliminary study on the dielectric properties and curing of three different types of epoxy resins mixed at various stoichiometric mixture of hardener, flydust and aluminium powder under microwav...This paper presents a preliminary study on the dielectric properties and curing of three different types of epoxy resins mixed at various stoichiometric mixture of hardener, flydust and aluminium powder under microwave energy. In this work, the curing process of thin layers of epoxy resins using microwave radiation was investigated as an alternative technique that can’ be implemented to develop a new rapid product development technique. In this study it was observed that the curing time and temperature were a function of the percentage of hardener and fillers presence in the epoxy resins. Initially dielectric properties of epoxy resins with hardener were measured which was directly correlated to the curing process in order to understand the properties of cured specimen. Tensile tests were conducted on the three different types of epoxy resins with hardener and fillers. Modifying dielectric properties of the mixtures a significant decrease in curing time was observed. In order to study the microstructural changes of cured specimen the morphology of the fracture surface was carried out by using scanning electron microscopy.展开更多
An adhesive of the SiBCN ceramic was synthesized through the polymer derived ceramics(PDC)route.Meanwhile with higher adhesion strength and simpler process condition,the polyborosilazane(PSNB)was modified by E-44 epox...An adhesive of the SiBCN ceramic was synthesized through the polymer derived ceramics(PDC)route.Meanwhile with higher adhesion strength and simpler process condition,the polyborosilazane(PSNB)was modified by E-44 epoxy resin.The E-44 epoxy resin was used to promote the oxidation process of SiBCN,in other words,to produce more amount of SiO2-B2O3 glasses.The phase composition,elemental analysis,chemical bonds and microstructure were investigated by using X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),and scanning electron microscope(SEM)measurements.The E-44 modified adhesives were cured at 120℃in air for 2 h,and were pyrolyzed at 1200,1400,and 1500℃for 2 h in air,respectively.The highest adhesion strength of the modified adhesive was up to 5.33,12.23,and 12.50 MPa after being heat treated at 1200,1400,and 1500℃,respectively.Finally,we proposed an adhesion model and revealed the adhesion mechanism of SiBCN ceramic.展开更多
Two kinds of tough ductile heatresisting thermoplastic, namely bisphenol A polysulfone (PSF) and polyethersulfone (PES) were used to toughen thermoset epoxy resin. A systematic study on the relationship between the mo...Two kinds of tough ductile heatresisting thermoplastic, namely bisphenol A polysulfone (PSF) and polyethersulfone (PES) were used to toughen thermoset epoxy resin. A systematic study on the relationship between the molecular weight and the terminal group of the thermoplastic modifier and the fracture toughness of the modified resin was carried out. The morphology of PSF modified epoxy resin was surveyed. With the same kind of PSF the structure of the epoxy resin and the toughening effect of PSF was also investigated. The fractography of PSF, particle modified epoxy was examined in detail with SEM. The contribution of every possible energy absorption process has been discussed. Crack pinning mechanism seems to be the most important toughening mechanism for tough ductile thermoplastic PSF particle modified epoxy system.展开更多
This paper discusses the fundamental principle of microwave heating, and based on the advantages of microwave heating, use maleic anhydride as curing agent. The technology of microwave curing E44 epoxy resins is inves...This paper discusses the fundamental principle of microwave heating, and based on the advantages of microwave heating, use maleic anhydride as curing agent. The technology of microwave curing E44 epoxy resins is investigated, the mechanical properties of cured epoxy resin samples in different contents of curbing agent by microwave and thermal curing methods are measured respectively, and then some experimental results for which are obtained. At last, this paper analyses why microwave curing can improve mechanical property of epoxy resin.展开更多
Epoxy resin (EPR) was used to crosslink with Camellia oleifera Abel.protein to prepare wood adhesive,and the bonding performance and curing characteristics of which were mainly investigated,and the synthesis mechanism...Epoxy resin (EPR) was used to crosslink with Camellia oleifera Abel.protein to prepare wood adhesive,and the bonding performance and curing characteristics of which were mainly investigated,and the synthesis mechanism was also discussed by using model compounds.The experimental results show that EPR can significantly improve the bonding performance of Camellia oleifera Abel.protein-based adhesive,and the maximum of which reaches 0.72 MPa satisfies the strength requirement of Type II plywood in GB/T 17657-2013.After alkali treatment,the protein can more easily crosslink with EPR at low curing temperature,and the adhesive has high degree of crystallinity of curing products,high degree of crosslinking reaction,and high bonding strength.The reaction mechanism of EPR-modified Camellia oleifera Abel.protein adhesive can be divided into resinification phase and curing phase.展开更多
The present work involves the development of siliconized epoxy resin to overcome the drawback of epoxy resin like poor impact strength, high rigidity and moisture absorbing nature because of which they are not applied...The present work involves the development of siliconized epoxy resin to overcome the drawback of epoxy resin like poor impact strength, high rigidity and moisture absorbing nature because of which they are not applied as corrosion resistant coating. By embedding silicone into the back bone of polymeric resin the above drawback can be reduced to substantial level. For achieving this, siliconised epoxy resins were prepared by reacting amine terminated silicone resin with novolac epoxy resin and meta-phenylenediamine was used as curing agent. The applied films of coating were baked at 150oC. Cured films were evaluated for their thermal, mechanical, chemical and corrosion resistance properties to ascertain the commercial utility of these eco-friendly resin for use in anti corrosive formulations. The siliconized epoxy resins system was found to exhibit good thermal and anticorrosive properties.展开更多
It is essential to design economic and efficient tougheners to prepare high-performance epoxy resin;however,this has remained a huge challenge.Herein,an eco-friendly,low-cost,and facile-fabricated bio-based hyperbranc...It is essential to design economic and efficient tougheners to prepare high-performance epoxy resin;however,this has remained a huge challenge.Herein,an eco-friendly,low-cost,and facile-fabricated bio-based hyperbranched toughener,carboxylic acid-functionalized tannic acid(CATA),was successfully prepared and applicated to the preparation of solvent-free epoxy resins.The mechanical performance,morphology,structural characterization,and thermal characterization of toughened epoxy resin system were studied.The toughened epoxy resin system with only 1.0wt%CATA reached the highest impact strength,111%higher than the neat epoxy resin system.Notably,the tensile strength and elongation at break of toughened epoxy resin systems increased moderately with increasing CATA loading.Nonphase-separated hybrids with significant toughening effect were obtained.Additionally,the thermal stabilities of toughened epoxy resin systems decreased with increasing CATA loading.This study provides an eco-friendly,cost-effective,and facile approach for the preparation of high-performance,solvent-free epoxy resins with potential for practical applications in sealing integrated circuits and electrical devices fields.展开更多
By using NaOH and Na2SiO3 as the activator,the mechanical properties and shrinkage of the geopolymer after incorporation of 0%,10%,20%,and 30% epoxy resin were investigated.The mechanism of epoxy resin toughening meta...By using NaOH and Na2SiO3 as the activator,the mechanical properties and shrinkage of the geopolymer after incorporation of 0%,10%,20%,and 30% epoxy resin were investigated.The mechanism of epoxy resin toughening metakaolin based geopolymer was analyzed by X-ray diffraction,scanning electron microscopy and Fourier transform infrared spectroscopy.It was shown that with the increases of epoxy resin,the shrinkage performance was obviously improved and the flexural strength increased by 53.5%.The compressive strength of EGP10,EGP20,and EGP30 increased by 49.12%,57.04%,and 65.34% after curing for 28 days,respectively.There were five obvious vibration peaks of 811 cm^-1,1 000 cm^-1,1 050 cm^-1,1 590cm^-1,and 3 400 cm^-1 in the geopolymer and the undisturbed metakaolin.More geopolymer gels were formed in the material and the microstructure was more compact.展开更多
The influence of the type of epoxy resins (E-51, F-51) on the mechanical properties and mi-crostructure of carboxyl-terminated butadiene nitrile rubber ( CTBN) toughened epoxy resins was investigated by determination ...The influence of the type of epoxy resins (E-51, F-51) on the mechanical properties and mi-crostructure of carboxyl-terminated butadiene nitrile rubber ( CTBN) toughened epoxy resins was investigated by determination of adhesive strength and toughness as well as observation of scanning electron microstructure (SEM). The resuhs indicate that the adhesive strength of CTBN toughened E-51 system is superior to CTBN toughened F-51 system. However, CTBN toughened E-51 system is inferior to CTBN toughened F-51 system in the toughness . This difference is related to the microstructure of two toughened systems . For CTBN toughened F-51, larger cavities and rubber particles are found in the system.. The larger cavities easily cause stress concentration and result in decrease of the adhesive strength. While the larger rubber particles may better terminate the development of crazing and shear banding and result in increase of the toughness .展开更多
The phase inversion emulsification technique (PIET) is an effective physical method for preparing waterbornedispersions of polymer resins. Some results concerning the preparation of bisphenol A epoxy resin waterborne ...The phase inversion emulsification technique (PIET) is an effective physical method for preparing waterbornedispersions of polymer resins. Some results concerning the preparation of bisphenol A epoxy resin waterborne dispersions byPIET in our laboratory were summarized. Electrical properties, rheological behavior and morphological evolution duringphase inversion progress were systematically characterized. The effects of the emulsifier concentration and emulsificationtemperature on phase inversion progress and the structural features of the waterborne particles were studied as well. Thedeformation and break up of water drops in a shear field were analyzed in terms of micro-rheology, while the interaction andcoalescence dynamics of water drops were discussed in terms of DLVO theory and Smoluchowski effective collision theory,respectively. Based on the experimental results and theoretical analysis, a physical model of phase inversion progress wassuggested, by which the effects of the parameters on phase inversion progress and the structural features of the waterborneparticles were interpreted and predicted.展开更多
Phenolic hydroxyl-terminated polysiloxanes were incorporated into epoxy resins to reducethe internal stress owing to the mismatch in coefficient of thermal expansion (CTE).Polysiloxane-epoxy resin block copolymers wer...Phenolic hydroxyl-terminated polysiloxanes were incorporated into epoxy resins to reducethe internal stress owing to the mismatch in coefficient of thermal expansion (CTE).Polysiloxane-epoxy resin block copolymers were made by a pre-reaction step prior to thecuring. In the cured resin, the domain size of the polysiloxane phase depended on thestructure of the phenolic hydroxyl-terminated polysiloxane. It was found that the modulus ofthe cured resin depended largely on the level of the modifier, while the CTE was affectedgreatly by the structure of the polysiloxane. By means of incorporating a few percent ofmethylphenylsiloxane unit into the polydimethylsiloxane chain, or by introducing morecompatible end-capping groups, the compounds of more effective low stress modifiers weresynthesized.展开更多
Epoxy resin(EP)tends to accumulate a large amount of charge on its surface when exposed to a high-voltage DC electric field,which leads to a reduction in its insulative performance and an increase in potential safety ...Epoxy resin(EP)tends to accumulate a large amount of charge on its surface when exposed to a high-voltage DC electric field,which leads to a reduction in its insulative performance and an increase in potential safety risks in power systems.To suppress charge accumulation,improve the flashover voltage of the EP,and reduce the risk of gas insulated switchgear(GIS)/gas insulated transmission line(GIL)failure,we used two plasma-etching methods,i.e.,atmospheric-pressure dielectric barrier discharge(DBD)and the atmospheric-pressure plasma jet(APPJ),to modify the surface of the EP.The surface morphology and electrical properties of the modified materials were explored as a function of time.The results show that after DBD treatment,the roughness of the sample increases by 103.9 nm,the conductivity increases by3.9×10^(-18)S,and the flashover voltage increases by 14.4%;after APPJ treatment,the roughness of the sample increases by 223.5 nm,the conductivity increases by 3.4×10^(-17)S,and the flashover voltage increases by 18%.This shows that both plasma-etching methods can improve the insulation properties of materials by improving the surface-charge characteristics.The two methods are compared with each other:the APPJ treatment method is better at improving the surface roughness and electrical properties of materials,and this flexible treatment method has greater potential in industrial applications.展开更多
Transparent wood has potential application in intelligent building,solar cell,electronics,and other advanced materials,while its single functionability hinders its further development.Flexible transparent wood(FTW)was...Transparent wood has potential application in intelligent building,solar cell,electronics,and other advanced materials,while its single functionability hinders its further development.Flexible transparent wood(FTW)was prepared by alkaline pretreatment and bleaching treat-ment of paulownia wood followed by impregnation of epoxy resin and ethylene glycol diglycidyl ether(EDGE).The eff ect of delignifi cation degree on the optical and mechani-cal properties of FTW was studied,and the infl uence of the epoxy/EDGE ratio on the fl exibility and mechanical proper-ties of FTW was also investigated.The results showed that higher delignifi cation degree resulted in higher transmit-tance of FTW.More EDGE addition led to better fl exibility of FTW,while overmuch addition of EDGE will reduce the mechanical properties.The optimal FTW sample resulted in a high transmittance of 89%and an ultrahigh haze value of 97%with outstanding fl exibility and excellent mechanical properties.The investigation of FTW broadens the research fi eld of transparent wood,and provides great possibility for its application in fl exible wearable devices and fl exible materials.展开更多
基金financially supported by the National Natural Science Foundation of China (22178242)。
文摘A flame retardant containing multiple antiflaming elements usually exhibits high-efficient flame retardancy. Here, a novel P/N/Si-containing ammonium polyphosphate derivative(APTES-APP) is synthesized from ammonium polyphosphate(APP) and silane coupling agent(3-aminopropyl)triethoxysilane(APTES)via cation exchange, which is quite different in the chemical structure from APTES-modified APP for retaining silicon hydroxyls. APTES-APP is highly efficient for the epoxy resin. 8%(mass) APTES-APP imparts excellent flame retardancy to the epoxy resin, with a V-0 rating at the UL-94 test(1.6 mm)and an LOI value of 26%(vol). The peak heat release rate and total smoke production of the flameretardant epoxy resin are decreased by 68.1% and 31.3%, respectively. The synergy of P/N/Si contributes to the well-expanded char residue with a strong and dense surface layer, which is a very good barrier against heat and mass transfer. Besides, there is no significant deterioration in the mechanical properties of flame-retardant epoxy resin thanks to silicon hydroxyls forming hydrogen bonds with epoxy molecules. Meanwhile, other molecules can be grafted onto APTES-APP via these silicon hydroxyls, if needed.Briefly, this work has developed a new strategy for amino silane as flame retardants. In conjunction with a low-cost and simple preparation method, APTES-APP has a promising prospect in the high-performance flame-retardant epoxy.
基金Natural Science Foundation of Jiangsu Province,China(No.BK 20180244)Foundation of Qing Lan Project,ChinaOpening Project of Key Laboratory of Jiangsu Province for Silk Engineering,Soochow University,China(No.KJS2278)。
文摘A graphene oxide/nano-silica(GOS)hybrid was rapidly and easily synthesized using graphene oxide(GO)and nano-silica(nano-SiO_(2))as raw materials,and the synthesized GOS was used to improve the mechanical properties of epoxy resin(EP).The modified EP with different mass fractions of GOS(0,0.1%,0.2%,0.3%and 0.4%)were prepared and studied.The structure,thermal stability,mechanical properties,fracture toughness and failure morphology of the modified EP were analyzed.The results showed that the tensile strength of GOS modified EP increased from 40.6 MPa to 80.2 MPa compared with EP,the critical stress intensity factor of GOS modified EP increased by 65.9%from 0.82 MPa·m^(1/2)to 1.36 MPa·m^(1/2),indicating a significant enhancement in fracture toughness.In addition,failure morphology was observed by scanning electron microscopy(SEM)observation.The toughness mechanism of the modified EP was also discussed.Finally,the thermal stability of the modified EP was improved by the addition of GOS.Compared with neat EP,the initial thermal degradation temperature and glass transition temperature of GOS modified EP increased by 4.5℃and 10.3℃,respectively.
基金the Core Research Facilities of College of Chemistry and Molecular Sciences and Wuhan University Test Center and Open Fund of Hubei Key Laboratory of Aerospace Power Advanced Technologythe Open Fund of Hubei Key Laboratory of Aerospace Power Advanced Technologythe Special Fund for Industrial and informatization Industry Foundation Reconstruction and High Quality Development of Manufacturing Industry(No.TC220H068)。
文摘We improved the adhesion between silicon based insulating materials and epoxy resin composites by adding the adhesion promoter cycloborosiloxane(BSi,cyclo-1,3,3,5,7,7-hexaphenyl-1,5-diboro-3,7-disiloxane).The experimental results show that the addition of BSi in the silicone rubber(SR)system significantly increases the tensile shear strength between BSi and epoxy resin(EP),reaching 309%of the original value.On this basis,the mechanism of BSi to enhance the adhesion effect was discussed.The electron deficient B in BSi attracted the electron rich N and O in EP to enhance the chemical interaction,combined with the interfacial migration behavior in the curing process,to improve the adhesion strength.This study provides the design and synthesis ideas of adhesive aids,and a reference for further exploring the interface mechanism of epoxy resin matrix composites.
文摘In this study,the durability of a new polymer carbonfiber-reinforced epoxy resin used to produce composite material in the aerospacefield is investigated through analysis of the corrosion phenomena occurring at the microscopic scale,and the related infrared spectra and thermal properties.It is found that light and heat can con-tribute to the aging process.In particular,the longitudinal tensile strength displays a non-monotonic trend,i.e.,itfirst increases and then decreases over time.By contrast,the longitudinal compressive and inter-laminar shear strengths do not show significant changes.It is also shown that the inter-laminar shear strength of carbonfiber/epoxy resin composites with inter-laminar hybrid structure is better than that of pure carbonfiber materials.The related resistance to corrosion can be improved by more than 41%.
基金supported by the Natural Science Foundation of China(51804332,51974355)Major Scientific and Technological Projects of CNPC(ZD2019-184-003)+1 种基金Provincial Geological Exploration Fund of Guizhou Province(208-9912-JBN-UTS0)Shandong Provincial Natural Science Foundation(ZR2017LEE005).
文摘The mechanical properties of Portland cement differ from the weakly consolidated shallow formation in deep water.This results in undesired abrupt changes in the compressive strength and elastic modulus at the cement–formation interface.In this study,a water-borne epoxy resin was applied as a strengthening material to reinforce the weakly consolidated shallow formation and protect the cement sheath from potential failure.The mechanical properties of the unconsolidated clay were tested,including their changes with increases in the temperature and curing time.In addition,the effects of the seawater,cement slurry alkaline filtrate,and saltwater drilling fluid were evaluated.As confirmed by the results,the strengthening fluid was excellent at reinforcing the unconsolidated clay,with a compressive strength of 2.49 MPa(after curing for 7 days),even at a dosage of 5%.A cement slurry filtrate with a high pH was suitable to produce the required strengthening of the formation,especially its early age strength.It should also be pointed out that the used fluid exhibited good compatibility with the saltwater drilling fluid and seawater behaved well as a diluent for the strengthening fluid.
基金This project is supported by the Scientific Fund of Polymer Physics Laboratory,Institute of Chemistry,Chinese Academy of Sciences.
文摘Werborne ultrafine particles of epoxy resin were prepared by phase inversion tech-nique. The results of SEM revealed that the particles diameter was in the range of 50to 100 nm and the effects on amount of water required at phase inversion point were alsodisc?d.
文摘This paper presents a preliminary study on the dielectric properties and curing of three different types of epoxy resins mixed at various stoichiometric mixture of hardener, flydust and aluminium powder under microwave energy. In this work, the curing process of thin layers of epoxy resins using microwave radiation was investigated as an alternative technique that can’ be implemented to develop a new rapid product development technique. In this study it was observed that the curing time and temperature were a function of the percentage of hardener and fillers presence in the epoxy resins. Initially dielectric properties of epoxy resins with hardener were measured which was directly correlated to the curing process in order to understand the properties of cured specimen. Tensile tests were conducted on the three different types of epoxy resins with hardener and fillers. Modifying dielectric properties of the mixtures a significant decrease in curing time was observed. In order to study the microstructural changes of cured specimen the morphology of the fracture surface was carried out by using scanning electron microscopy.
基金Funded by the Research Fund of the National Key Research and Development Program of China(No.2017YFB0703200)the State Key Laboratory of Solidification Processing(NWPU),China(No.135-QP-2015)the Fundamental Research Funds for the Central Universities(No.3102017zy058).
文摘An adhesive of the SiBCN ceramic was synthesized through the polymer derived ceramics(PDC)route.Meanwhile with higher adhesion strength and simpler process condition,the polyborosilazane(PSNB)was modified by E-44 epoxy resin.The E-44 epoxy resin was used to promote the oxidation process of SiBCN,in other words,to produce more amount of SiO2-B2O3 glasses.The phase composition,elemental analysis,chemical bonds and microstructure were investigated by using X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),and scanning electron microscope(SEM)measurements.The E-44 modified adhesives were cured at 120℃in air for 2 h,and were pyrolyzed at 1200,1400,and 1500℃for 2 h in air,respectively.The highest adhesion strength of the modified adhesive was up to 5.33,12.23,and 12.50 MPa after being heat treated at 1200,1400,and 1500℃,respectively.Finally,we proposed an adhesion model and revealed the adhesion mechanism of SiBCN ceramic.
基金Sponsored by the National Natural Science Foundation of China
文摘Two kinds of tough ductile heatresisting thermoplastic, namely bisphenol A polysulfone (PSF) and polyethersulfone (PES) were used to toughen thermoset epoxy resin. A systematic study on the relationship between the molecular weight and the terminal group of the thermoplastic modifier and the fracture toughness of the modified resin was carried out. The morphology of PSF modified epoxy resin was surveyed. With the same kind of PSF the structure of the epoxy resin and the toughening effect of PSF was also investigated. The fractography of PSF, particle modified epoxy was examined in detail with SEM. The contribution of every possible energy absorption process has been discussed. Crack pinning mechanism seems to be the most important toughening mechanism for tough ductile thermoplastic PSF particle modified epoxy system.
基金The research was supported by the open fund from the State Key Laboratory of Advanced Technology for Materials Synthesis and Processing(SKJ-9805)
文摘This paper discusses the fundamental principle of microwave heating, and based on the advantages of microwave heating, use maleic anhydride as curing agent. The technology of microwave curing E44 epoxy resins is investigated, the mechanical properties of cured epoxy resin samples in different contents of curbing agent by microwave and thermal curing methods are measured respectively, and then some experimental results for which are obtained. At last, this paper analyses why microwave curing can improve mechanical property of epoxy resin.
基金Funded by the Science and Technology Department Program of Guizhou Province (ZK[2021]162 and [2019]2325)the Special Project of"Doctor Professor Service Group of Kaili University (BJFWT201906)+1 种基金the Cultivation Project of Guizhou University of China ([2019]37)the Camellia Engineering Technology Research Center of Guizhou Province ([2018]5252)。
文摘Epoxy resin (EPR) was used to crosslink with Camellia oleifera Abel.protein to prepare wood adhesive,and the bonding performance and curing characteristics of which were mainly investigated,and the synthesis mechanism was also discussed by using model compounds.The experimental results show that EPR can significantly improve the bonding performance of Camellia oleifera Abel.protein-based adhesive,and the maximum of which reaches 0.72 MPa satisfies the strength requirement of Type II plywood in GB/T 17657-2013.After alkali treatment,the protein can more easily crosslink with EPR at low curing temperature,and the adhesive has high degree of crystallinity of curing products,high degree of crosslinking reaction,and high bonding strength.The reaction mechanism of EPR-modified Camellia oleifera Abel.protein adhesive can be divided into resinification phase and curing phase.
文摘The present work involves the development of siliconized epoxy resin to overcome the drawback of epoxy resin like poor impact strength, high rigidity and moisture absorbing nature because of which they are not applied as corrosion resistant coating. By embedding silicone into the back bone of polymeric resin the above drawback can be reduced to substantial level. For achieving this, siliconised epoxy resins were prepared by reacting amine terminated silicone resin with novolac epoxy resin and meta-phenylenediamine was used as curing agent. The applied films of coating were baked at 150oC. Cured films were evaluated for their thermal, mechanical, chemical and corrosion resistance properties to ascertain the commercial utility of these eco-friendly resin for use in anti corrosive formulations. The siliconized epoxy resins system was found to exhibit good thermal and anticorrosive properties.
基金from the Special Fund for the Program for Zhejiang Provincial Natural Science Foundation of China(LZ16C160001)National Key Research and Development Program(2017YFD0601105),the National Natural Science Foundation of China(Grant No.21806142)the Zhejiang Provincial Natural Science Foundation of China(Grant No.LY20B070002).
文摘It is essential to design economic and efficient tougheners to prepare high-performance epoxy resin;however,this has remained a huge challenge.Herein,an eco-friendly,low-cost,and facile-fabricated bio-based hyperbranched toughener,carboxylic acid-functionalized tannic acid(CATA),was successfully prepared and applicated to the preparation of solvent-free epoxy resins.The mechanical performance,morphology,structural characterization,and thermal characterization of toughened epoxy resin system were studied.The toughened epoxy resin system with only 1.0wt%CATA reached the highest impact strength,111%higher than the neat epoxy resin system.Notably,the tensile strength and elongation at break of toughened epoxy resin systems increased moderately with increasing CATA loading.Nonphase-separated hybrids with significant toughening effect were obtained.Additionally,the thermal stabilities of toughened epoxy resin systems decreased with increasing CATA loading.This study provides an eco-friendly,cost-effective,and facile approach for the preparation of high-performance,solvent-free epoxy resins with potential for practical applications in sealing integrated circuits and electrical devices fields.
基金the National Natural Science Foundation of China(No.51574055)。
文摘By using NaOH and Na2SiO3 as the activator,the mechanical properties and shrinkage of the geopolymer after incorporation of 0%,10%,20%,and 30% epoxy resin were investigated.The mechanism of epoxy resin toughening metakaolin based geopolymer was analyzed by X-ray diffraction,scanning electron microscopy and Fourier transform infrared spectroscopy.It was shown that with the increases of epoxy resin,the shrinkage performance was obviously improved and the flexural strength increased by 53.5%.The compressive strength of EGP10,EGP20,and EGP30 increased by 49.12%,57.04%,and 65.34% after curing for 28 days,respectively.There were five obvious vibration peaks of 811 cm^-1,1 000 cm^-1,1 050 cm^-1,1 590cm^-1,and 3 400 cm^-1 in the geopolymer and the undisturbed metakaolin.More geopolymer gels were formed in the material and the microstructure was more compact.
基金This project was supported by Open Foundation of State Key Lab. of Advanced Technology for Materials Synthesis and Process-ing.
文摘The influence of the type of epoxy resins (E-51, F-51) on the mechanical properties and mi-crostructure of carboxyl-terminated butadiene nitrile rubber ( CTBN) toughened epoxy resins was investigated by determination of adhesive strength and toughness as well as observation of scanning electron microstructure (SEM). The resuhs indicate that the adhesive strength of CTBN toughened E-51 system is superior to CTBN toughened F-51 system. However, CTBN toughened E-51 system is inferior to CTBN toughened F-51 system in the toughness . This difference is related to the microstructure of two toughened systems . For CTBN toughened F-51, larger cavities and rubber particles are found in the system.. The larger cavities easily cause stress concentration and result in decrease of the adhesive strength. While the larger rubber particles may better terminate the development of crazing and shear banding and result in increase of the toughness .
基金This work was supported by the National Key Project for Fundamental Research, "Macromolecular Condensed State" of Ministry of Science and Technology of China and National Natural Science Foundation of China 29774038.
文摘The phase inversion emulsification technique (PIET) is an effective physical method for preparing waterbornedispersions of polymer resins. Some results concerning the preparation of bisphenol A epoxy resin waterborne dispersions byPIET in our laboratory were summarized. Electrical properties, rheological behavior and morphological evolution duringphase inversion progress were systematically characterized. The effects of the emulsifier concentration and emulsificationtemperature on phase inversion progress and the structural features of the waterborne particles were studied as well. Thedeformation and break up of water drops in a shear field were analyzed in terms of micro-rheology, while the interaction andcoalescence dynamics of water drops were discussed in terms of DLVO theory and Smoluchowski effective collision theory,respectively. Based on the experimental results and theoretical analysis, a physical model of phase inversion progress wassuggested, by which the effects of the parameters on phase inversion progress and the structural features of the waterborneparticles were interpreted and predicted.
文摘Phenolic hydroxyl-terminated polysiloxanes were incorporated into epoxy resins to reducethe internal stress owing to the mismatch in coefficient of thermal expansion (CTE).Polysiloxane-epoxy resin block copolymers were made by a pre-reaction step prior to thecuring. In the cured resin, the domain size of the polysiloxane phase depended on thestructure of the phenolic hydroxyl-terminated polysiloxane. It was found that the modulus ofthe cured resin depended largely on the level of the modifier, while the CTE was affectedgreatly by the structure of the polysiloxane. By means of incorporating a few percent ofmethylphenylsiloxane unit into the polydimethylsiloxane chain, or by introducing morecompatible end-capping groups, the compounds of more effective low stress modifiers weresynthesized.
基金supported by National Natural Science Foundation of China(Nos.51777076,51507066)the Fundamental Research Funds for the Central Universities(Nos.2019MS083,2018MS084)the Self-topic Fund of State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources(Nos.LAPS202116,LAPS202103)。
文摘Epoxy resin(EP)tends to accumulate a large amount of charge on its surface when exposed to a high-voltage DC electric field,which leads to a reduction in its insulative performance and an increase in potential safety risks in power systems.To suppress charge accumulation,improve the flashover voltage of the EP,and reduce the risk of gas insulated switchgear(GIS)/gas insulated transmission line(GIL)failure,we used two plasma-etching methods,i.e.,atmospheric-pressure dielectric barrier discharge(DBD)and the atmospheric-pressure plasma jet(APPJ),to modify the surface of the EP.The surface morphology and electrical properties of the modified materials were explored as a function of time.The results show that after DBD treatment,the roughness of the sample increases by 103.9 nm,the conductivity increases by3.9×10^(-18)S,and the flashover voltage increases by 14.4%;after APPJ treatment,the roughness of the sample increases by 223.5 nm,the conductivity increases by 3.4×10^(-17)S,and the flashover voltage increases by 18%.This shows that both plasma-etching methods can improve the insulation properties of materials by improving the surface-charge characteristics.The two methods are compared with each other:the APPJ treatment method is better at improving the surface roughness and electrical properties of materials,and this flexible treatment method has greater potential in industrial applications.
基金funded by the National Natural Science Foundation of China(31760183)the Natural Science Foundation of Guangxi(2016GXNSFCA380025)+1 种基金the Project Funded by China Postdoctoral Science Foundation(2017M620361)the Scientifi c Research Foundation of Guangxi University(XGZ150513).
文摘Transparent wood has potential application in intelligent building,solar cell,electronics,and other advanced materials,while its single functionability hinders its further development.Flexible transparent wood(FTW)was prepared by alkaline pretreatment and bleaching treat-ment of paulownia wood followed by impregnation of epoxy resin and ethylene glycol diglycidyl ether(EDGE).The eff ect of delignifi cation degree on the optical and mechani-cal properties of FTW was studied,and the infl uence of the epoxy/EDGE ratio on the fl exibility and mechanical proper-ties of FTW was also investigated.The results showed that higher delignifi cation degree resulted in higher transmit-tance of FTW.More EDGE addition led to better fl exibility of FTW,while overmuch addition of EDGE will reduce the mechanical properties.The optimal FTW sample resulted in a high transmittance of 89%and an ultrahigh haze value of 97%with outstanding fl exibility and excellent mechanical properties.The investigation of FTW broadens the research fi eld of transparent wood,and provides great possibility for its application in fl exible wearable devices and fl exible materials.
