The synthesis and characterization of a new class of cementitious composites filled with polymer emulsions were investigated, and their superior mechanical strength and durability properties compared to composites dev...The synthesis and characterization of a new class of cementitious composites filled with polymer emulsions were investigated, and their superior mechanical strength and durability properties compared to composites devoid of fi llers were reported. Polymer emulsions were utilized to mechanically reinforce the composite and bridge the cement, fly ash, aggregate and fibers. The results reveal that the epoxy emulsion and poly（ethylene-co-vinyl acetate） emulsion markedly enhance the mechanical and durability properties of cemetitious composites. The fi bers can be pulled out in the form of slip-hardening and the abrasion phenomenon can be observed clearly on the surface of the fibers. The hydration extent of cement is higher than that of the pristine composites. The polymer modified cementitious composites designed on micromechanics, have fl exibility and plasticity which could be applied for a novel form of multifunctional materials with a range of pipeline coatings applications.展开更多
A novel engineered cementitious composite(ECC) was prepared with the complex binder of Portland cement and asphalt emulsion.By adjusting the amount of asphalt emulsion,different mixture proportions were adopted in exp...A novel engineered cementitious composite(ECC) was prepared with the complex binder of Portland cement and asphalt emulsion.By adjusting the amount of asphalt emulsion,different mixture proportions were adopted in experiments,including four-point bending test,compressive test,and scanning electric microscopy(SEM).The SEM observation was conducted to evaluate the contribution of polyvinyl alcohol(PVA) fiber and asphalt emulsion to the composite toughening mechanism.The tests results show that the most remarkable deflection-hardening behavior and saturated multiple cracking are achieved when the content of asphalt emulsion is 10%.However,excessive content of asphalt emulsion causes severe damages on the deformation behavior as well as loss in compressive strength of the mixture.SEM observation indicates that the influence of asphalt emulsion on the fiber/matrix interfacial property changes the dominant fiber failure type from rupture into pull-out mode,and thus causes beneficial effects for strain-hardening behavior.展开更多
A polarizing microscope,X-ray diffraction(XRD),fourier transform infrared spectrometer(FTIR),scanning electron microscope and energy dispersive spectrometer(SEM-EDS),X-ray photoelectron spectroscopy(XPS),and micro com...A polarizing microscope,X-ray diffraction(XRD),fourier transform infrared spectrometer(FTIR),scanning electron microscope and energy dispersive spectrometer(SEM-EDS),X-ray photoelectron spectroscopy(XPS),and micro computed tomography(Micro CT)were used to investigate the relation between the structure and properties of the composite.Meanwhile,the physical properties,mechanical properties and strength mechanism were researched.The experimental results show that the structure and morphology of coated phosphogypsum remain intact in the composite,which shows good compatibility and forms a clear interface layer of transition zone between the coated phosphogypsum and the matrix,conforming to the structure of particle reinforced inorganic composites.The emulsion coated phosphogypsum has a certain strengthening effect on the aluminous rock mineral polymer composite.The compressive strength of the composite can reach 16.5 MPa when the amount of coated phosphogypsum is 40%,and the apparent density is 1.75 g·cm^(-3),which is significantly lower than that of common concrete;the thermal stability of the composite is also improved to a certain extent.Some certain chemical reactions occur in the process of forming the matrix of aluminous rock mineral polymer materials,with a structure of three-dimensional network.The research will provide a new way for the comprehensive utilization of phosphogypsum and low-grade aluminous rock.展开更多
It was tried to prepare composite particles made of polymer and two kinds of solid powders by forming Pickeringemulsion followed by the drying-in-liquid method and to investigate how the stepwise addition of solid pow...It was tried to prepare composite particles made of polymer and two kinds of solid powders by forming Pickeringemulsion followed by the drying-in-liquid method and to investigate how the stepwise addition of solid powders affected the contained ratio and adhesion ratio of solid powders and the structure of composite particles. Limonene oil dissolving expanded polystyrene and ethylene glycol were adopted as the dispersed phase and the continuous phase, respectively. Magnetite and titanium dioxide were used as solid powders. Magnetite was added before or after formation of the (O/W) dispersion. Titanium dioxide was added at the various elapsed times from addition of magnetite. Titanium dioxide adhered only on the surface of composite particles irrespective of addition time. At the earlier addition of both solid powders, the surface-covering type composite particles were prepared. At the latter addition of titanium dioxide, a part of magnetite adhered on the surface and the remainder was dispersed into composite particle.展开更多
The booming development of DIW technology present an unprecedented prospect in energetic materials field and has attracted great interest due to its relative simplicity and high flexibility of manufacturing.Herein,a n...The booming development of DIW technology present an unprecedented prospect in energetic materials field and has attracted great interest due to its relative simplicity and high flexibility of manufacturing.Herein,a novel CL-20 based explosive ink formulation have been developed successfully for MEMS initiation systems via DIW technology.We designed PVA/GAP into an oil-in-water(O/W)emulsion,in the way that the aqueous solution of PVA as water phase,the ethyl acetate solution of GAP as oil phase,the combination of Tween 80 and SDS as emulsifier,BPS as a curing agent of GAP.The ideal formulation with good shear-thinning rheology properties and clear gel point was prepared using only 10 wt%emulsion.The dual-cured network formed during the curing process made the printed sample have good mechanical properties.The printed samples had satisfactory molding effect without cracks or fractures,the crystal form of CL-20 not changed and the thermal stability have improved.Deposition of explosive inks via DIW in micro-scale grooves had excellent detonation performances,which critical detonation size was 1×0.045 mm,detonation velocity was 7129 m/s and when the corner reaching 150°can still detonated stably.This study may open new avenues for developing binder systems in explosive ink formulations.展开更多
Nano-calcium carbonate composite particles were synthesized by the soapless emulsion polymerization technique of double monomers. The composite particles formation mechanism was investigated. The effects of composite ...Nano-calcium carbonate composite particles were synthesized by the soapless emulsion polymerization technique of double monomers. The composite particles formation mechanism was investigated. The effects of composite particles on the mechanical properties of nano-CaCO3-ABS （acrylonitrile-butadiene-styrene copolymer） composite material were studied. It was validated that the composite particles are made up of the nano-calcium carbonate cores and the shells of alternating copolymers of butyl acrylate （BA） and styrene （St）. The shells are chemically grafted and physically wrapped on the surface of nano-calcium carbonate particles. When the composite particles were filled in ABS matrix, the CaCO3 particles are homogeneously dispersed in the composite material as nanoscales. The impact strength of the composite material is obviously enhanced after filling appropriate amounts of composite particles. It can be concluded that the soapless emulsion polymerization of double monomers is an effective method for nano-CaCO3 surface treatment. 2008 University of Science and Technology Beijing. All rights reserved.展开更多
Despite the great potential of cellulose wood pulp and cellulose nanofibrils as reinforcing filler in thermoplastics,its use is limited due to its tendency to form agglomerates and due to its high hydrophilic characte...Despite the great potential of cellulose wood pulp and cellulose nanofibrils as reinforcing filler in thermoplastics,its use is limited due to its tendency to form agglomerates and due to its high hydrophilic character.Here we describe fiberboard composites with high contents of wood pulp or cellulose nanofibrils,and a resin of poly(styrene-methyl-methacrylate-acrylic acid)used as water-based emulsion.Cellulose wood pulp and cellulose nanofibrils were used directly in the form of water suspensions.The method is based on the flocculation of the polymer emulsion followed by agglomeration of a mixture of the polymer emulsion and cellulose suspension,leading to the co-precipitation of the composite material,which can be easily separated from the water phase.Composites with acrylic polymer/cellulose fibers in the proportions of 75:25,50:50 and 25:75 wt%were prepared.Composites were characterized by scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR),thermogravimetric analysis(TGA),dynamic mechanical analysis(DMA)and water absorption tests.SEM analysis revealed a very good dispersion of the fibers without evidence of agglomeration,which led to superior mechanical properties.These results showed the effectiveness of the methodology and the potential of cellulose wood pulp and CNF as reinforcement fillers in fiberboard composites and any other high fiber-content materials.展开更多
Polysiloxane-polystyrene composite latexes were prepared by two-stage emulsionpolymerization. Polymerization of styrene in swollen polysiloxane latex particles were studied.Formation of simple polystyrene particle in ...Polysiloxane-polystyrene composite latexes were prepared by two-stage emulsionpolymerization. Polymerization of styrene in swollen polysiloxane latex particles were studied.Formation of simple polystyrene particle in the 2nd-stage polymerization depends on the particlesize of the lst-stage latex and the polymerization temperature. Polystyrene domains in thevulcanizates reinforce the silicone rubbers effectively.展开更多
The emulsion copolymerization of vinylidene chloride (VDC) with methyl-methacrylate(MMA) and acrylonitrile (AN) was carried out by batch, seeded batch and semicontinuous pro-cesses,respectively. Significant difference...The emulsion copolymerization of vinylidene chloride (VDC) with methyl-methacrylate(MMA) and acrylonitrile (AN) was carried out by batch, seeded batch and semicontinuous pro-cesses,respectively. Significant differences were found in the physical and mechanical propertiesof the latexes and films, depending on the methods of monomer feeding. The results both intheory and experiments demonstrated that the copolymer composition and the length of the VDC sequences in the copolymer could be controlled by the modes of monomer feeding process.展开更多
Gelatincarbonyl iron composite particle was prepared by micro emulsion method. The analysis of scanning electron microscope(SEM) shows that the ultrafine particles are spheroids coated by gelatin, and the average size...Gelatincarbonyl iron composite particle was prepared by micro emulsion method. The analysis of scanning electron microscope(SEM) shows that the ultrafine particles are spheroids coated by gelatin, and the average sizes of particles are 310μm. The specific saturation magnetization σ_s is 130.9A·m2/kg, coercivity H_c is 0.823A/m, and residual magnetism r is 4.98Am2/kg for the composite particles. It is shown that the particles possess properties of soft magnetic. The yield stress of magnetorheological fluid(MRF) with composite particle reaches 70kPa at 0.5T magnetic induction. Magnetorheological effects are superior in lower magnetic field intensity and the subsidence stability of the MRF is excellent compared with pure carbonyl iron powder.展开更多
This research investigates the formation of chitosan/poly(L-lactide) (CS/PLLA) porous composite scaffold using a novel emulsion freeze-drying technique. First, an oil in-water (O/W) emulsification system was used in t...This research investigates the formation of chitosan/poly(L-lactide) (CS/PLLA) porous composite scaffold using a novel emulsion freeze-drying technique. First, an oil in-water (O/W) emulsification system was used in the presence of surfactant Tween-80, in which CS solution was used as the water phase and PLLA solution was used as the oil phase. The emulsion was observed by inverted microscope (×200). The emulsion droplet was spherical and uniform in size. FT-IR analysis revealed that there were hydrogen bonding interactions between CS and PLLA components. The microstructure and physical properties of the scaffolds were also analyzed. The SEM results showed that composite scaffolds formed well interconnected pore structure and homogenous distribution of CS and PLLA. When the content of PLLA reached 50%, the porosity of CS/PLLA composite scaffolds were between 83%-91% and density in the range of 0.047 to 0.11 g/cm3. The porosity showed a slight decrease and the density increased with the increase of PLLA dose. The compressive strength increased from 0.32 to 0.43 MPa, while the compressive modulus increased from 1.99 to 3.91 MPa as the PLLA contents increased from 10% to 50%.展开更多
基金Funded by the National Natural Science Foundation of China(No.21076227)
文摘The synthesis and characterization of a new class of cementitious composites filled with polymer emulsions were investigated, and their superior mechanical strength and durability properties compared to composites devoid of fi llers were reported. Polymer emulsions were utilized to mechanically reinforce the composite and bridge the cement, fly ash, aggregate and fibers. The results reveal that the epoxy emulsion and poly（ethylene-co-vinyl acetate） emulsion markedly enhance the mechanical and durability properties of cemetitious composites. The fi bers can be pulled out in the form of slip-hardening and the abrasion phenomenon can be observed clearly on the surface of the fibers. The hydration extent of cement is higher than that of the pristine composites. The polymer modified cementitious composites designed on micromechanics, have fl exibility and plasticity which could be applied for a novel form of multifunctional materials with a range of pipeline coatings applications.
基金Project(2011BAE27B04)supported by the National Key Technology R&D Program of ChinaProjects(CHD2011TD003,CHD2011ZD017)supported by the Special Fund for Basic Scientific Research of Central Colleges in Chang’an University,China
文摘A novel engineered cementitious composite(ECC) was prepared with the complex binder of Portland cement and asphalt emulsion.By adjusting the amount of asphalt emulsion,different mixture proportions were adopted in experiments,including four-point bending test,compressive test,and scanning electric microscopy(SEM).The SEM observation was conducted to evaluate the contribution of polyvinyl alcohol(PVA) fiber and asphalt emulsion to the composite toughening mechanism.The tests results show that the most remarkable deflection-hardening behavior and saturated multiple cracking are achieved when the content of asphalt emulsion is 10%.However,excessive content of asphalt emulsion causes severe damages on the deformation behavior as well as loss in compressive strength of the mixture.SEM observation indicates that the influence of asphalt emulsion on the fiber/matrix interfacial property changes the dominant fiber failure type from rupture into pull-out mode,and thus causes beneficial effects for strain-hardening behavior.
基金Funded by the Science and Technology Support Plan of Guizhou Province(No.[2021]482)the Provincial University Joint Fund Project of Guizhou Science and Technology agency(No.[2014]7656)+1 种基金the Science and Technology Plan Project of Guizhou Province(No.[2020]1Z045)the Chunhui Plan of the National Department of Education of China(No.Z2006-1-52003)。
文摘A polarizing microscope,X-ray diffraction(XRD),fourier transform infrared spectrometer(FTIR),scanning electron microscope and energy dispersive spectrometer(SEM-EDS),X-ray photoelectron spectroscopy(XPS),and micro computed tomography(Micro CT)were used to investigate the relation between the structure and properties of the composite.Meanwhile,the physical properties,mechanical properties and strength mechanism were researched.The experimental results show that the structure and morphology of coated phosphogypsum remain intact in the composite,which shows good compatibility and forms a clear interface layer of transition zone between the coated phosphogypsum and the matrix,conforming to the structure of particle reinforced inorganic composites.The emulsion coated phosphogypsum has a certain strengthening effect on the aluminous rock mineral polymer composite.The compressive strength of the composite can reach 16.5 MPa when the amount of coated phosphogypsum is 40%,and the apparent density is 1.75 g·cm^(-3),which is significantly lower than that of common concrete;the thermal stability of the composite is also improved to a certain extent.Some certain chemical reactions occur in the process of forming the matrix of aluminous rock mineral polymer materials,with a structure of three-dimensional network.The research will provide a new way for the comprehensive utilization of phosphogypsum and low-grade aluminous rock.
文摘It was tried to prepare composite particles made of polymer and two kinds of solid powders by forming Pickeringemulsion followed by the drying-in-liquid method and to investigate how the stepwise addition of solid powders affected the contained ratio and adhesion ratio of solid powders and the structure of composite particles. Limonene oil dissolving expanded polystyrene and ethylene glycol were adopted as the dispersed phase and the continuous phase, respectively. Magnetite and titanium dioxide were used as solid powders. Magnetite was added before or after formation of the (O/W) dispersion. Titanium dioxide was added at the various elapsed times from addition of magnetite. Titanium dioxide adhered only on the surface of composite particles irrespective of addition time. At the earlier addition of both solid powders, the surface-covering type composite particles were prepared. At the latter addition of titanium dioxide, a part of magnetite adhered on the surface and the remainder was dispersed into composite particle.
基金This work was supported by the Graduate Education Innovation Project of Shanxi Province(2020SY401)No.55 Research Institute of China North Industries Group Corporation Open Innovation Fund(WDZC2020JJ017).
文摘The booming development of DIW technology present an unprecedented prospect in energetic materials field and has attracted great interest due to its relative simplicity and high flexibility of manufacturing.Herein,a novel CL-20 based explosive ink formulation have been developed successfully for MEMS initiation systems via DIW technology.We designed PVA/GAP into an oil-in-water(O/W)emulsion,in the way that the aqueous solution of PVA as water phase,the ethyl acetate solution of GAP as oil phase,the combination of Tween 80 and SDS as emulsifier,BPS as a curing agent of GAP.The ideal formulation with good shear-thinning rheology properties and clear gel point was prepared using only 10 wt%emulsion.The dual-cured network formed during the curing process made the printed sample have good mechanical properties.The printed samples had satisfactory molding effect without cracks or fractures,the crystal form of CL-20 not changed and the thermal stability have improved.Deposition of explosive inks via DIW in micro-scale grooves had excellent detonation performances,which critical detonation size was 1×0.045 mm,detonation velocity was 7129 m/s and when the corner reaching 150°can still detonated stably.This study may open new avenues for developing binder systems in explosive ink formulations.
基金the National Natural Science Foundation of China(No.20236020,20325621)the National R & D Program of China(No.2001BA310A01).
文摘Nano-calcium carbonate composite particles were synthesized by the soapless emulsion polymerization technique of double monomers. The composite particles formation mechanism was investigated. The effects of composite particles on the mechanical properties of nano-CaCO3-ABS （acrylonitrile-butadiene-styrene copolymer） composite material were studied. It was validated that the composite particles are made up of the nano-calcium carbonate cores and the shells of alternating copolymers of butyl acrylate （BA） and styrene （St）. The shells are chemically grafted and physically wrapped on the surface of nano-calcium carbonate particles. When the composite particles were filled in ABS matrix, the CaCO3 particles are homogeneously dispersed in the composite material as nanoscales. The impact strength of the composite material is obviously enhanced after filling appropriate amounts of composite particles. It can be concluded that the soapless emulsion polymerization of double monomers is an effective method for nano-CaCO3 surface treatment. 2008 University of Science and Technology Beijing. All rights reserved.
文摘Despite the great potential of cellulose wood pulp and cellulose nanofibrils as reinforcing filler in thermoplastics,its use is limited due to its tendency to form agglomerates and due to its high hydrophilic character.Here we describe fiberboard composites with high contents of wood pulp or cellulose nanofibrils,and a resin of poly(styrene-methyl-methacrylate-acrylic acid)used as water-based emulsion.Cellulose wood pulp and cellulose nanofibrils were used directly in the form of water suspensions.The method is based on the flocculation of the polymer emulsion followed by agglomeration of a mixture of the polymer emulsion and cellulose suspension,leading to the co-precipitation of the composite material,which can be easily separated from the water phase.Composites with acrylic polymer/cellulose fibers in the proportions of 75:25,50:50 and 25:75 wt%were prepared.Composites were characterized by scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR),thermogravimetric analysis(TGA),dynamic mechanical analysis(DMA)and water absorption tests.SEM analysis revealed a very good dispersion of the fibers without evidence of agglomeration,which led to superior mechanical properties.These results showed the effectiveness of the methodology and the potential of cellulose wood pulp and CNF as reinforcement fillers in fiberboard composites and any other high fiber-content materials.
文摘Polysiloxane-polystyrene composite latexes were prepared by two-stage emulsionpolymerization. Polymerization of styrene in swollen polysiloxane latex particles were studied.Formation of simple polystyrene particle in the 2nd-stage polymerization depends on the particlesize of the lst-stage latex and the polymerization temperature. Polystyrene domains in thevulcanizates reinforce the silicone rubbers effectively.
基金The project is supported by Beijing Natural Science Fund.
文摘The emulsion copolymerization of vinylidene chloride (VDC) with methyl-methacrylate(MMA) and acrylonitrile (AN) was carried out by batch, seeded batch and semicontinuous pro-cesses,respectively. Significant differences were found in the physical and mechanical propertiesof the latexes and films, depending on the methods of monomer feeding. The results both intheory and experiments demonstrated that the copolymer composition and the length of the VDC sequences in the copolymer could be controlled by the modes of monomer feeding process.
文摘Gelatincarbonyl iron composite particle was prepared by micro emulsion method. The analysis of scanning electron microscope(SEM) shows that the ultrafine particles are spheroids coated by gelatin, and the average sizes of particles are 310μm. The specific saturation magnetization σ_s is 130.9A·m2/kg, coercivity H_c is 0.823A/m, and residual magnetism r is 4.98Am2/kg for the composite particles. It is shown that the particles possess properties of soft magnetic. The yield stress of magnetorheological fluid(MRF) with composite particle reaches 70kPa at 0.5T magnetic induction. Magnetorheological effects are superior in lower magnetic field intensity and the subsidence stability of the MRF is excellent compared with pure carbonyl iron powder.
基金National Nature Science Foundation of China grant number: 50803032, 10925208, 11032012, 11002016 and 30800217Fundamental Research Funds for the Central Universities
文摘This research investigates the formation of chitosan/poly(L-lactide) (CS/PLLA) porous composite scaffold using a novel emulsion freeze-drying technique. First, an oil in-water (O/W) emulsification system was used in the presence of surfactant Tween-80, in which CS solution was used as the water phase and PLLA solution was used as the oil phase. The emulsion was observed by inverted microscope (×200). The emulsion droplet was spherical and uniform in size. FT-IR analysis revealed that there were hydrogen bonding interactions between CS and PLLA components. The microstructure and physical properties of the scaffolds were also analyzed. The SEM results showed that composite scaffolds formed well interconnected pore structure and homogenous distribution of CS and PLLA. When the content of PLLA reached 50%, the porosity of CS/PLLA composite scaffolds were between 83%-91% and density in the range of 0.047 to 0.11 g/cm3. The porosity showed a slight decrease and the density increased with the increase of PLLA dose. The compressive strength increased from 0.32 to 0.43 MPa, while the compressive modulus increased from 1.99 to 3.91 MPa as the PLLA contents increased from 10% to 50%.
