Dynamic rheological characteristics of polypropylene (PP) filled with ultra-fine full-vulcanized powdered rubber (UFPR) composed of styrene-butadiene copolymer were studied through dynamic rheological measurements on ...Dynamic rheological characteristics of polypropylene (PP) filled with ultra-fine full-vulcanized powdered rubber (UFPR) composed of styrene-butadiene copolymer were studied through dynamic rheological measurements on an Advanced Rheometric Expansion System (ARES). A specific viscoelastic phenomenon, i.e. 'the second plateau', appeared at low frequencies, and exhibits a certain dependence on the amount of rubber particles and the dispersion state in the matrix. This phenomenon is attributed to the formation of aggregation structure of rubber particles. The analyses of Cole-Cole diagrams of the dynamic viscoelastic functions suggest that the heterogeneity of the composites is enhanced on increasing both particle content and temperature.展开更多
According to the present theories of plastic toughening, it is impossible to enhance the toughness, stiffness and/orheat resistance of plastics simultaneously by using rubber. A series of novel nano-rubber particles (...According to the present theories of plastic toughening, it is impossible to enhance the toughness, stiffness and/orheat resistance of plastics simultaneously by using rubber. A series of novel nano-rubber particles (UFPR) were introduced,which were prepared through irradiating common rubber lattices and spray drying them. Epoxies toughened with UFPRshowed a much better toughening effect than those with CTBN, and the heat resistance of epoxy was unexpectedly elevated.For polypropylene toughening, UFPR can improve the toughness, stiffness and heat resistance of PP simultaneously. Thesespecial toughening effects overcome the deficiencies in rubber toughening technology and are worth further investigating.展开更多
Cerium carbonate powders were produced in a submerged circulation impinging stream reactor (SCISR) from Ce(NO3)3· 6H2O. NH4HCO3 was used as a precipitant in the reaction. Cerium carbonate powders were roasted...Cerium carbonate powders were produced in a submerged circulation impinging stream reactor (SCISR) from Ce(NO3)3· 6H2O. NH4HCO3 was used as a precipitant in the reaction. Cerium carbonate powders were roasted to produce ultra-fine cerium dioxide (CeO2) powders. The optimal conditions of such production process were obtained by orthogonal and one-factor experiments. The results showed that ultra-fine and narrowly distributed cerium carbonate powders were produced under the optimal flowing conditions. The concentrations of Ce(NO3)3 and NH4HCO3 solutions were 02,5 and 0.3 mol · L^-1, respectively. The concentration of PEG4000 added in these two solutions was 4 g · L^-1. The stirring ratio, reaction temperature, feeding time, solution pH, reaction time and digestion time were 900 r · min^- 1,80 ℃, 20 min, 5 - 6, 5 min and 1 h, respectively. The final product, CeO2 powders, was obtained by roasting the produced cerium carbonate in air for 3 h at 500 ℃. The finally produced CeO2 powders were torispherical particles with a narrow size distribution of 0.8 -2.5 μm. The crystal structure of CeO2 powders belonged to cubic crystal system and its space point 5 group was OH^5-FM3M. Under optimal conditions, powders produced by SCISR were finer and more narrowly distributed than that by Stirred Tank Reactor (STR).展开更多
The research on asphalt performance mainly focused on the macro performance and micro mechanism.Mesoscopic analysis was introduced to study the effect of rubber powder movement on asphalt rubber properties.After the p...The research on asphalt performance mainly focused on the macro performance and micro mechanism.Mesoscopic analysis was introduced to study the effect of rubber powder movement on asphalt rubber properties.After the preparation parameters and the preparation process of asphalt rubber were determined,the modification mechanism and rheological properties were analyzed which revealed the compatible stability mechanism.Then,the analysis model of asphalt rubber was established to focus on simulating the effect of rubber powder and the spatial movement on its mechanical properties.The experimental results show that rubber powder can make the asphalt rubber bear more uniform stress distribution and enhance the ability to resist deformation.Meanwhile,the rotational motion and final distribution of rubber powder have an obvious impact on the mechanical properties of asphalt rubber.In the selected feature points,the average stress of rubber powder at 0°space angle is only 34.1%of that at90°space angle.When the rubber powders are all in parallel in the ideal state,it enhances the mechanical properties the most.This study supplements the“mesoscopic”scale between macro and micro research.The relationship between micro mechanism and macro properties of asphalt rubber will be established from the mesoscopic perspective.It is also an effort to realize the effective correlation from micro,mesoscopic to macro in asphalt.展开更多
The ultra-fine chromic oxide powder was prepared by a novel gas-solid reduction reaction.Na2CrO4 was firstly reduced with hydrogen at 400-600 ℃.The obtained reduction products,mainly the mixture of NaCrO2 and sodium ...The ultra-fine chromic oxide powder was prepared by a novel gas-solid reduction reaction.Na2CrO4 was firstly reduced with hydrogen at 400-600 ℃.The obtained reduction products,mainly the mixture of NaCrO2 and sodium hydroxide(NaOH),were converted into chromic oxide through hydrolysis followed by calcination.The obtained chromic oxide product was characterized by powder X-ray diffraction(XRD) and SEM.The results show that the hydrolysis process of sodium chromite is the key step and lower reduction temperature helps intensify the hydrolysis process.展开更多
In this study, three kinds of modified ultra-fine ceramic powders marked A, B and C, which were prepared by each of three different modifiers mixing with a commercial SiC, were added to HT250 cast iron, respectively, ...In this study, three kinds of modified ultra-fine ceramic powders marked A, B and C, which were prepared by each of three different modifiers mixing with a commercial SiC, were added to HT250 cast iron, respectively, and the effects of the modified ultra-fine ceramic powders on microstructure, mechanical properties and wear resistance were studied. Metallographic examination, tensile test, scanning electron microscopy, and three-dimensional surface topography were applied to analyze and compare the samples containing modified powder with the original samples. The results showed that the most obvious modification effect among the powders was seen in the sample containing powder A, with the graphite and eutectic cells being refined, the tensile strength being increased by 36.9%, and the wear resistance being improved by 45.5% and 47.2% under loads of 150 N and 300 N, respectively. The improvements of mechanical properties and wear resistance in the HT250 cast iron with the modified ultra-fine ceramic powders were attributed to the synergistic effect of the grain refinement with the powder acting as a hard particle phase and the lubrication by the graphite.展开更多
The powdered coal ash (PCA) was classified, then the ash particle (- 45μm) was modified by a surface active agent and obtained modified powder coal ash (MPCA). The character of the MPC was investigated, when it was u...The powdered coal ash (PCA) was classified, then the ash particle (- 45μm) was modified by a surface active agent and obtained modified powder coal ash (MPCA). The character of the MPC was investigated, when it was used as a new type reinforced filler of rubber.The results show that MPCA can replace or party replace carbon black or silica as reinforced fillers of rubbers.展开更多
The effciency of sodium hydroxide treated rubber (Hevea brasiliensis) leaves powder (NHBL) for removing copper ions from aqueous solutions has been investigated. The e?ects of physicochemical parameters on biosorption...The effciency of sodium hydroxide treated rubber (Hevea brasiliensis) leaves powder (NHBL) for removing copper ions from aqueous solutions has been investigated. The e?ects of physicochemical parameters on biosorption capacities such as stirring speed, pH, biosorbent dose, initial concentrations of copper, and ionic strength were studied. The biosorption capacities of NHBL increased with increase in pH, stirring speed and copper concentration but decreased with increase in biosorbent dose and ionic strength. The isotherm study indicated that NHBL fitted well with Langmuir model compared to Freundlich and Dubinin-Radushkevich models. The maximum biosorption capacity determined from Langmuir isotherm was 14.97 mg/g at 27°C. The kinetic study revealed that pseudo- second order model fitted well the kinetic data, while Boyd kinetic model indicated that film diffusion was the main rate determining step in biosorption process. Based on surface area analysis, NHBL has low surface area and categorized as macroporous. Fourier transform infrared (FT-IR) analyses revealed that hydroxyl, carboxyl, and amino are the main functional groups involved in the binding of copper ions. Complexation was one of the main mechanisms for the removal of copper ions as indicated by FT-IR spectra. Ion exchange was another possible mechanism since the ratio of adsorbed cations (Cu2+ and H+) to the released cations (Na+, Ca2+, and Mg2+) from NHBL was almost unity. Copper ions bound on NHBL were able to be desorbed at > 99% using 0.05 mol/L HCl, 0.01 mol/L HNO3, and 0.01 mol/L EDTA solutions.展开更多
Rubber leaf powder (an agricultural waste) was treated with potassium permanganate followed by sodium carbonate and its performance in the removal of Pb(II) ions from aqueous solution was evaluated. The interactio...Rubber leaf powder (an agricultural waste) was treated with potassium permanganate followed by sodium carbonate and its performance in the removal of Pb(II) ions from aqueous solution was evaluated. The interactions between Pb(II) ions and functional groups on the adsorbent surface were confirmed by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) coupled with X-ray energy dispersive spectroscopy (EDX). The effects of several important parameters which can affect adsorption capacity such as pH, adsorbent dosage, initial lead concentration and contact time were studied. The optimum pH range for lead adsorption was 4-5. Even at very low adsorbent dosage of 0.02 g, almost 100% of Pb(II) ions (23 mg/L) could be removed. The adsorption capacity was also dependent on lead concentration and contact time, and relatively a short period of time (60-90 min) was required to reach equilibrium. The equilibrium data were analyzed with Langmuir, Freundlich and Dubinin-Radushkevich isotherms. Based on Langmuir model, the maximum adsorption capacity of lead was 95.3 mg/g. Three kinetic models including pseudo first-order, pseudo second-order and Boyd were used to analyze the lead adsorption process, and the results showed that the pseudo second-order fitted well with correlation coefficients greater than 0.99.展开更多
This research focused on using the waste rubber powder as a kind of regenerate resources to improve the mechanical properties of cement mortar.The two kinds of hybrid modified rubber powder TRP and ATRP were prepared ...This research focused on using the waste rubber powder as a kind of regenerate resources to improve the mechanical properties of cement mortar.The two kinds of hybrid modified rubber powder TRP and ATRP were prepared by sol-gel method and then used in cement mortar.The structures and properties of them were studied.It is shown that the nano Si-O-Si network is generated in TRP and ATRP networks and the hydrophilic group is grafted on the surface of ATRP.The mechanical properties of rubber-treated mortar(RTM) were tested and the microstructures of them were also studied.Compared to the mortars with unmodified rubber powders(RP),NaOH treated rubber powder(SRP) and coupling agent treated rubber powder(CRP),the RTM with ATRP has the highest compressive strength and flexural strength.The stress-strain curves shown that the peak of stress of RTM with ATRP is increased and indicated the higher compression deformation and toughness.It is found that the interfacial adhesion between the ATRP and cement mortar is increased distinctly by SEM,which results in enhanced ductility and mechanical properties of RTM with ATRP.展开更多
A system of producing scrap rubber powder with wave cryogenic technology isput forward. Main equipments such as wave refrigerator, vortex pulverizer and fluidized cooler arepresented. The key techniques about silica g...A system of producing scrap rubber powder with wave cryogenic technology isput forward. Main equipments such as wave refrigerator, vortex pulverizer and fluidized cooler arepresented. The key techniques about silica gel refreshing in desiccators and system drying arediscussed. The potential improvement of the system is pointed out. The manufacturing cost is lowerthan the cost of liquid nitrogen cryogenic method, and the quality is better than that of normaltemperature milling. Moreover, wave refrigerators have several advantages over turbine expendersapplied in the cryogenic milling system.展开更多
Ultra-fine CeO_2-ZrO_2 mixed oxide was successfully synthesized by wet-solid phase mechanochemical processing, Ce_2(CO_3)_3·8H_2O, ZrOCl_2·xH_2O and ammonia were used as reactants. It is found that the cryst...Ultra-fine CeO_2-ZrO_2 mixed oxide was successfully synthesized by wet-solid phase mechanochemical processing, Ce_2(CO_3)_3·8H_2O, ZrOCl_2·xH_2O and ammonia were used as reactants. It is found that the crystalline Ce_2(CO_3)_3·8H_2O and ZrOCl_2·xH_2O are changed to amorphous cerium and zirconium hydroxide precursor after milling with ammonia, and Ce_(0.15)Zr_(0.85)O_2 mixed oxide with pure tetragonal phase structure and medium particle size(D_(50))less than 1μm is formed by calcining precursor over 673 K. The XRD patterns indicate that the crystal unite size increases with rising calcining temperature due to crystal growth. However, the particle size and BET surface area of the Ce(Zr)O_2 mixed oxide decreases with rising calcining temperature, which may be attributed to the contract of particles and the vanish of holes inside grains.展开更多
A layered charge composed of the JH-2 explosive enveloped by a thick-walled cylindrical casing(active aluminum/rubber and inert lithium fluoride/rubber composites) was designed and explosion experiments were conducted...A layered charge composed of the JH-2 explosive enveloped by a thick-walled cylindrical casing(active aluminum/rubber and inert lithium fluoride/rubber composites) was designed and explosion experiments were conducted in a 1.3 m3tank and a 113 m3bunker.The blast parameters,including the quasistatic pressure(ΔpQS),special impulse(I),and peak overpressure(Δpmax),and images of the explosion process were recorded,and the influence of the Al content(30% and 50%) and Al particle size(1,10,and 50 μm) on the energy release of aluminum/rubber composites were investigated.The results revealed that the use of an active layer increased the peak overpressure generated by the primary blast wave,as well as the quasistatic pressure and special impulse related to fuel burning within tens of milliseconds after detonation.When the Al content was increased from 30% to 50%,the increases of ΔpQS and I were not obvious,and Δpmaxeven decreased,possibly because of decreased combustion efficiency and greater absorption of the blast wave energy for layers with 50% Al.Compared with the pure JH-2charge,the charge with 1 μm Al particles produced the highest Δpmax,indicating that better transient blast performance was generated by smaller Al particles.However,the charge with 10 μm Al particles showed the largest ΔpQSand I,suggesting that a stronger destructive effect occurred over a longer duration for charges that contained moderate 10 μm Al.展开更多
A series of natural rubber-snail shell powder vulcanizates were compounded on a two-roll mill, and moulded on a compression moulding machine. The mechanical and end-use properties of the natural rubber vulcanizates we...A series of natural rubber-snail shell powder vulcanizates were compounded on a two-roll mill, and moulded on a compression moulding machine. The mechanical and end-use properties of the natural rubber vulcanizates were investigated at snail shell powder contents, 0 to 20 pphr. The snail shell powder was characterized for filler properties and sieved to 0.075, and 0.30 μm particle sizes. Carbon black was used as the reference filler. Results showed that the tensile strength, modulus, elongation at break, and resilience of the rubber vulcanizates were not enhanced on addition of snail shell powder. The hardness of the rubber vulcanizes were marginally increased at high snail shell powder content. However, the specific gravity of the rubber vulcanizates showed increases with increase in snail shell powder content. At a filler content above 5 pphr, snail shell powder exhibited good flame retardant property in the vulcanizates. The swelling indices of snail shell powder (0.075 μm) filled natural rubber were generally good, and better than those of snail shell powder (0.30 μm) filled natural rubber. Carbon black was found to show more property improvement for the natural rubber vulcanizates when compared to snail shell powder. Although the mechanical properties of snail shell powder filled natural rubber vulcanizates were not good, there were improvements in the end-use properties, an indication that snail shell powder could still find utilization in the rubber industry where specific end-use property of a rubber product is required.展开更多
The effect of the deferent rubber content substituted for fine aggregate on the mortar performance was studied.The effects of the rubber coated with the coating materials on the mortar compressive strength,bending str...The effect of the deferent rubber content substituted for fine aggregate on the mortar performance was studied.The effects of the rubber coated with the coating materials on the mortar compressive strength,bending strength and impact work were discussed.The optimum rubber powder content and the suitable coating material were found.Through the electrical probe test-BEI,SEI and calcium ion distribution,and the slight crack and the interface between the rubber and cement matrix are analyzed.The results show that the rubber powder coated with the surface treatment materials A,B and C has the capability of absorbing a large amount of energy under the compressive and flexural load and the slight cracks of R-C were controlled and restrained.展开更多
In view of the disadvantage that the mechanical properties of cement-based composites can be significantly reduced by incorporating waste rubber powder in situ, the surface modification methods of the original rubber ...In view of the disadvantage that the mechanical properties of cement-based composites can be significantly reduced by incorporating waste rubber powder in situ, the surface modification methods of the original rubber powder by coupling agent KH560, sodium hydroxide, polyvinyl alcohol (PVA), methyl hydroxyethyl cellulose ether (MHEC) and tetraethyl orthosilicate (TEOS) as precursors were adopted respectively. The modification of waste rubber powder was studied by Change rate of mortar strength of cement-based composite mortar mixed with waste rubber powder. The results show that the hybrid modification method using tetraethyl orthosilicate as precursor has better ef-fect. When 5 phr ethyl orthosilicate is added, the compressive strength and flexural strength of cement-based composite mortar can be increased by 31.7% and 28%. Scanning electron microscopy (SEM) results show that the surface of waste rubber powder with good modification effect has many pro-trusions and flake-like porous structures which are beneficial to its bonding with cement-based materials.展开更多
Corn stalk cellulose(CS)/used rubber powder(RP)composites were prepared by mixing,the silane coupling agent 3-Mercaptopropyl trimethoxysilane(KH590),r-Aminopropyltrieth oxysilane(KH550),isopropyl dioleic(dioctylphosph...Corn stalk cellulose(CS)/used rubber powder(RP)composites were prepared by mixing,the silane coupling agent 3-Mercaptopropyl trimethoxysilane(KH590),r-Aminopropyltrieth oxysilane(KH550),isopropyl dioleic(dioctylphosphate)titanate(HY101)and bis-(γ-triethoxysilylpropyl)-tetrasulfide(Si69)were used to modify the interface of composites.The effects of the CS and coupling agents on the mechanical properties,thermal properties,interfacial morphology and structure of the composites were investigated,respectively.The results showed that the addition of CS could effectively improve the mechanical properties of the composites.Compared with the untreated composites,the interfacial bonding between CS and RP was significantly improved by the coupling modification treatment,and the tensile strength and elongation at break of composites with Si69 increased by 3.13 MPa and 10%,respectively,the Si69 showed the best coupling modification effect,followed by KH590,then KH550 and HY101 when the CS content was 25 pph(part per hundred)and coupling agent 1.5 pph,and the thermal decomposition temperature increased by 30℃.展开更多
In this experimental study,the impact of Portland cement replacement by ground granulated blast furnace slag(GGBFS)and micronized rubber powder(MRP)on the compressive,flexural,tensile strengths,and rapid chloride migr...In this experimental study,the impact of Portland cement replacement by ground granulated blast furnace slag(GGBFS)and micronized rubber powder(MRP)on the compressive,flexural,tensile strengths,and rapid chloride migration test(RCMT)of concrete were assessed.In this study,samples with different binder content and water to binder ratios,including the MRP with the substitution levels of 0%,2.5%and 5%,and the GGBFS with the substitution ratios of 0%,20%and 40%by weight of Portland cement were made.According to the results,in the samples containing slag and rubber powder in the early ages,on average,a 12.2%decrease in the mechanical characteristics of concrete was observed,nonetheless with raising the age of the samples,the impact of slag on reducing the porosity of concrete lowered the negative impact of rubber powder.Regarding durability characteristics,the RCMT results of the samples were enhanced by using rubber powder because of its insulation impact.Moreover,adding slag into the MRP-included mixtures results in a 23%reduction in the migration rate of the chloride ion averagely.At last,four mathematical statements were derived for the mechanical and durability of concrete containing the MRP and GGBFS utilizing the genetic programming method.展开更多
基金This work was supported by the National Science Fund for Distinguished Young Scholars of China (No.50125312) andSpecial Funds for Major State Basic Research Projects (No.G1999064800).
文摘Dynamic rheological characteristics of polypropylene (PP) filled with ultra-fine full-vulcanized powdered rubber (UFPR) composed of styrene-butadiene copolymer were studied through dynamic rheological measurements on an Advanced Rheometric Expansion System (ARES). A specific viscoelastic phenomenon, i.e. 'the second plateau', appeared at low frequencies, and exhibits a certain dependence on the amount of rubber particles and the dispersion state in the matrix. This phenomenon is attributed to the formation of aggregation structure of rubber particles. The analyses of Cole-Cole diagrams of the dynamic viscoelastic functions suggest that the heterogeneity of the composites is enhanced on increasing both particle content and temperature.
基金This work was financially supported by the Special Funds for Major State Basic Research Projects of China (No. G1999064800).
文摘According to the present theories of plastic toughening, it is impossible to enhance the toughness, stiffness and/orheat resistance of plastics simultaneously by using rubber. A series of novel nano-rubber particles (UFPR) were introduced,which were prepared through irradiating common rubber lattices and spray drying them. Epoxies toughened with UFPRshowed a much better toughening effect than those with CTBN, and the heat resistance of epoxy was unexpectedly elevated.For polypropylene toughening, UFPR can improve the toughness, stiffness and heat resistance of PP simultaneously. Thesespecial toughening effects overcome the deficiencies in rubber toughening technology and are worth further investigating.
基金Project supported by the National Natural Science Foundation of China (50474022 and 50574069 )
文摘Cerium carbonate powders were produced in a submerged circulation impinging stream reactor (SCISR) from Ce(NO3)3· 6H2O. NH4HCO3 was used as a precipitant in the reaction. Cerium carbonate powders were roasted to produce ultra-fine cerium dioxide (CeO2) powders. The optimal conditions of such production process were obtained by orthogonal and one-factor experiments. The results showed that ultra-fine and narrowly distributed cerium carbonate powders were produced under the optimal flowing conditions. The concentrations of Ce(NO3)3 and NH4HCO3 solutions were 02,5 and 0.3 mol · L^-1, respectively. The concentration of PEG4000 added in these two solutions was 4 g · L^-1. The stirring ratio, reaction temperature, feeding time, solution pH, reaction time and digestion time were 900 r · min^- 1,80 ℃, 20 min, 5 - 6, 5 min and 1 h, respectively. The final product, CeO2 powders, was obtained by roasting the produced cerium carbonate in air for 3 h at 500 ℃. The finally produced CeO2 powders were torispherical particles with a narrow size distribution of 0.8 -2.5 μm. The crystal structure of CeO2 powders belonged to cubic crystal system and its space point 5 group was OH^5-FM3M. Under optimal conditions, powders produced by SCISR were finer and more narrowly distributed than that by Stirred Tank Reactor (STR).
基金Funded by the Key Research and Development Projects in Shaanxi Province (2022SF-328)the Science and Technology Project of Henan Department of Transportation (2020J-2-3)the Science and Technology Project of Shaanxi Department of Transportation (Nos.19-10K and 19-28K)。
文摘The research on asphalt performance mainly focused on the macro performance and micro mechanism.Mesoscopic analysis was introduced to study the effect of rubber powder movement on asphalt rubber properties.After the preparation parameters and the preparation process of asphalt rubber were determined,the modification mechanism and rheological properties were analyzed which revealed the compatible stability mechanism.Then,the analysis model of asphalt rubber was established to focus on simulating the effect of rubber powder and the spatial movement on its mechanical properties.The experimental results show that rubber powder can make the asphalt rubber bear more uniform stress distribution and enhance the ability to resist deformation.Meanwhile,the rotational motion and final distribution of rubber powder have an obvious impact on the mechanical properties of asphalt rubber.In the selected feature points,the average stress of rubber powder at 0°space angle is only 34.1%of that at90°space angle.When the rubber powders are all in parallel in the ideal state,it enhances the mechanical properties the most.This study supplements the“mesoscopic”scale between macro and micro research.The relationship between micro mechanism and macro properties of asphalt rubber will be established from the mesoscopic perspective.It is also an effort to realize the effective correlation from micro,mesoscopic to macro in asphalt.
基金Funded by the Key Program Project of the National Natural Science Foundation of China (No.50234040)the Major Project of the Knowledge Innovation Program of the Chinese Academy of Sciences (No.KCCX1-SW-22)
文摘The ultra-fine chromic oxide powder was prepared by a novel gas-solid reduction reaction.Na2CrO4 was firstly reduced with hydrogen at 400-600 ℃.The obtained reduction products,mainly the mixture of NaCrO2 and sodium hydroxide(NaOH),were converted into chromic oxide through hydrolysis followed by calcination.The obtained chromic oxide product was characterized by powder X-ray diffraction(XRD) and SEM.The results show that the hydrolysis process of sodium chromite is the key step and lower reduction temperature helps intensify the hydrolysis process.
基金financially supported by the National Natural Science Foundation of China(grant no.51204028)
文摘In this study, three kinds of modified ultra-fine ceramic powders marked A, B and C, which were prepared by each of three different modifiers mixing with a commercial SiC, were added to HT250 cast iron, respectively, and the effects of the modified ultra-fine ceramic powders on microstructure, mechanical properties and wear resistance were studied. Metallographic examination, tensile test, scanning electron microscopy, and three-dimensional surface topography were applied to analyze and compare the samples containing modified powder with the original samples. The results showed that the most obvious modification effect among the powders was seen in the sample containing powder A, with the graphite and eutectic cells being refined, the tensile strength being increased by 36.9%, and the wear resistance being improved by 45.5% and 47.2% under loads of 150 N and 300 N, respectively. The improvements of mechanical properties and wear resistance in the HT250 cast iron with the modified ultra-fine ceramic powders were attributed to the synergistic effect of the grain refinement with the powder acting as a hard particle phase and the lubrication by the graphite.
文摘The powdered coal ash (PCA) was classified, then the ash particle (- 45μm) was modified by a surface active agent and obtained modified powder coal ash (MPCA). The character of the MPC was investigated, when it was used as a new type reinforced filler of rubber.The results show that MPCA can replace or party replace carbon black or silica as reinforced fillers of rubbers.
基金Universiti Sains Malaysia for the financial support under Short Term Research Grant(Grant No.304/PKIMIA/638056)
文摘The effciency of sodium hydroxide treated rubber (Hevea brasiliensis) leaves powder (NHBL) for removing copper ions from aqueous solutions has been investigated. The e?ects of physicochemical parameters on biosorption capacities such as stirring speed, pH, biosorbent dose, initial concentrations of copper, and ionic strength were studied. The biosorption capacities of NHBL increased with increase in pH, stirring speed and copper concentration but decreased with increase in biosorbent dose and ionic strength. The isotherm study indicated that NHBL fitted well with Langmuir model compared to Freundlich and Dubinin-Radushkevich models. The maximum biosorption capacity determined from Langmuir isotherm was 14.97 mg/g at 27°C. The kinetic study revealed that pseudo- second order model fitted well the kinetic data, while Boyd kinetic model indicated that film diffusion was the main rate determining step in biosorption process. Based on surface area analysis, NHBL has low surface area and categorized as macroporous. Fourier transform infrared (FT-IR) analyses revealed that hydroxyl, carboxyl, and amino are the main functional groups involved in the binding of copper ions. Complexation was one of the main mechanisms for the removal of copper ions as indicated by FT-IR spectra. Ion exchange was another possible mechanism since the ratio of adsorbed cations (Cu2+ and H+) to the released cations (Na+, Ca2+, and Mg2+) from NHBL was almost unity. Copper ions bound on NHBL were able to be desorbed at > 99% using 0.05 mol/L HCl, 0.01 mol/L HNO3, and 0.01 mol/L EDTA solutions.
基金the Malaysian Ministry of Higher Education for providing financial support(No.011000070004)
文摘Rubber leaf powder (an agricultural waste) was treated with potassium permanganate followed by sodium carbonate and its performance in the removal of Pb(II) ions from aqueous solution was evaluated. The interactions between Pb(II) ions and functional groups on the adsorbent surface were confirmed by Fourier transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM) coupled with X-ray energy dispersive spectroscopy (EDX). The effects of several important parameters which can affect adsorption capacity such as pH, adsorbent dosage, initial lead concentration and contact time were studied. The optimum pH range for lead adsorption was 4-5. Even at very low adsorbent dosage of 0.02 g, almost 100% of Pb(II) ions (23 mg/L) could be removed. The adsorption capacity was also dependent on lead concentration and contact time, and relatively a short period of time (60-90 min) was required to reach equilibrium. The equilibrium data were analyzed with Langmuir, Freundlich and Dubinin-Radushkevich isotherms. Based on Langmuir model, the maximum adsorption capacity of lead was 95.3 mg/g. Three kinetic models including pseudo first-order, pseudo second-order and Boyd were used to analyze the lead adsorption process, and the results showed that the pseudo second-order fitted well with correlation coefficients greater than 0.99.
文摘This research focused on using the waste rubber powder as a kind of regenerate resources to improve the mechanical properties of cement mortar.The two kinds of hybrid modified rubber powder TRP and ATRP were prepared by sol-gel method and then used in cement mortar.The structures and properties of them were studied.It is shown that the nano Si-O-Si network is generated in TRP and ATRP networks and the hydrophilic group is grafted on the surface of ATRP.The mechanical properties of rubber-treated mortar(RTM) were tested and the microstructures of them were also studied.Compared to the mortars with unmodified rubber powders(RP),NaOH treated rubber powder(SRP) and coupling agent treated rubber powder(CRP),the RTM with ATRP has the highest compressive strength and flexural strength.The stress-strain curves shown that the peak of stress of RTM with ATRP is increased and indicated the higher compression deformation and toughness.It is found that the interfacial adhesion between the ATRP and cement mortar is increased distinctly by SEM,which results in enhanced ductility and mechanical properties of RTM with ATRP.
文摘A system of producing scrap rubber powder with wave cryogenic technology isput forward. Main equipments such as wave refrigerator, vortex pulverizer and fluidized cooler arepresented. The key techniques about silica gel refreshing in desiccators and system drying arediscussed. The potential improvement of the system is pointed out. The manufacturing cost is lowerthan the cost of liquid nitrogen cryogenic method, and the quality is better than that of normaltemperature milling. Moreover, wave refrigerators have several advantages over turbine expendersapplied in the cryogenic milling system.
文摘Ultra-fine CeO_2-ZrO_2 mixed oxide was successfully synthesized by wet-solid phase mechanochemical processing, Ce_2(CO_3)_3·8H_2O, ZrOCl_2·xH_2O and ammonia were used as reactants. It is found that the crystalline Ce_2(CO_3)_3·8H_2O and ZrOCl_2·xH_2O are changed to amorphous cerium and zirconium hydroxide precursor after milling with ammonia, and Ce_(0.15)Zr_(0.85)O_2 mixed oxide with pure tetragonal phase structure and medium particle size(D_(50))less than 1μm is formed by calcining precursor over 673 K. The XRD patterns indicate that the crystal unite size increases with rising calcining temperature due to crystal growth. However, the particle size and BET surface area of the Ce(Zr)O_2 mixed oxide decreases with rising calcining temperature, which may be attributed to the contract of particles and the vanish of holes inside grains.
基金funded by the National Natural Science Foundation of China(Grant No.11972018)the Defense Pre-Research Joint Foundation of Chinese Ordnance Industry(Grant No.6141B012858)。
文摘A layered charge composed of the JH-2 explosive enveloped by a thick-walled cylindrical casing(active aluminum/rubber and inert lithium fluoride/rubber composites) was designed and explosion experiments were conducted in a 1.3 m3tank and a 113 m3bunker.The blast parameters,including the quasistatic pressure(ΔpQS),special impulse(I),and peak overpressure(Δpmax),and images of the explosion process were recorded,and the influence of the Al content(30% and 50%) and Al particle size(1,10,and 50 μm) on the energy release of aluminum/rubber composites were investigated.The results revealed that the use of an active layer increased the peak overpressure generated by the primary blast wave,as well as the quasistatic pressure and special impulse related to fuel burning within tens of milliseconds after detonation.When the Al content was increased from 30% to 50%,the increases of ΔpQS and I were not obvious,and Δpmaxeven decreased,possibly because of decreased combustion efficiency and greater absorption of the blast wave energy for layers with 50% Al.Compared with the pure JH-2charge,the charge with 1 μm Al particles produced the highest Δpmax,indicating that better transient blast performance was generated by smaller Al particles.However,the charge with 10 μm Al particles showed the largest ΔpQSand I,suggesting that a stronger destructive effect occurred over a longer duration for charges that contained moderate 10 μm Al.
文摘A series of natural rubber-snail shell powder vulcanizates were compounded on a two-roll mill, and moulded on a compression moulding machine. The mechanical and end-use properties of the natural rubber vulcanizates were investigated at snail shell powder contents, 0 to 20 pphr. The snail shell powder was characterized for filler properties and sieved to 0.075, and 0.30 μm particle sizes. Carbon black was used as the reference filler. Results showed that the tensile strength, modulus, elongation at break, and resilience of the rubber vulcanizates were not enhanced on addition of snail shell powder. The hardness of the rubber vulcanizes were marginally increased at high snail shell powder content. However, the specific gravity of the rubber vulcanizates showed increases with increase in snail shell powder content. At a filler content above 5 pphr, snail shell powder exhibited good flame retardant property in the vulcanizates. The swelling indices of snail shell powder (0.075 μm) filled natural rubber were generally good, and better than those of snail shell powder (0.30 μm) filled natural rubber. Carbon black was found to show more property improvement for the natural rubber vulcanizates when compared to snail shell powder. Although the mechanical properties of snail shell powder filled natural rubber vulcanizates were not good, there were improvements in the end-use properties, an indication that snail shell powder could still find utilization in the rubber industry where specific end-use property of a rubber product is required.
文摘The effect of the deferent rubber content substituted for fine aggregate on the mortar performance was studied.The effects of the rubber coated with the coating materials on the mortar compressive strength,bending strength and impact work were discussed.The optimum rubber powder content and the suitable coating material were found.Through the electrical probe test-BEI,SEI and calcium ion distribution,and the slight crack and the interface between the rubber and cement matrix are analyzed.The results show that the rubber powder coated with the surface treatment materials A,B and C has the capability of absorbing a large amount of energy under the compressive and flexural load and the slight cracks of R-C were controlled and restrained.
文摘In view of the disadvantage that the mechanical properties of cement-based composites can be significantly reduced by incorporating waste rubber powder in situ, the surface modification methods of the original rubber powder by coupling agent KH560, sodium hydroxide, polyvinyl alcohol (PVA), methyl hydroxyethyl cellulose ether (MHEC) and tetraethyl orthosilicate (TEOS) as precursors were adopted respectively. The modification of waste rubber powder was studied by Change rate of mortar strength of cement-based composite mortar mixed with waste rubber powder. The results show that the hybrid modification method using tetraethyl orthosilicate as precursor has better ef-fect. When 5 phr ethyl orthosilicate is added, the compressive strength and flexural strength of cement-based composite mortar can be increased by 31.7% and 28%. Scanning electron microscopy (SEM) results show that the surface of waste rubber powder with good modification effect has many pro-trusions and flake-like porous structures which are beneficial to its bonding with cement-based materials.
基金supported by 2019 Science and Graduate Innovative Research Project of Qiqihar University Heilongjiang Province,China(YJSCX2019060).
文摘Corn stalk cellulose(CS)/used rubber powder(RP)composites were prepared by mixing,the silane coupling agent 3-Mercaptopropyl trimethoxysilane(KH590),r-Aminopropyltrieth oxysilane(KH550),isopropyl dioleic(dioctylphosphate)titanate(HY101)and bis-(γ-triethoxysilylpropyl)-tetrasulfide(Si69)were used to modify the interface of composites.The effects of the CS and coupling agents on the mechanical properties,thermal properties,interfacial morphology and structure of the composites were investigated,respectively.The results showed that the addition of CS could effectively improve the mechanical properties of the composites.Compared with the untreated composites,the interfacial bonding between CS and RP was significantly improved by the coupling modification treatment,and the tensile strength and elongation at break of composites with Si69 increased by 3.13 MPa and 10%,respectively,the Si69 showed the best coupling modification effect,followed by KH590,then KH550 and HY101 when the CS content was 25 pph(part per hundred)and coupling agent 1.5 pph,and the thermal decomposition temperature increased by 30℃.
文摘In this experimental study,the impact of Portland cement replacement by ground granulated blast furnace slag(GGBFS)and micronized rubber powder(MRP)on the compressive,flexural,tensile strengths,and rapid chloride migration test(RCMT)of concrete were assessed.In this study,samples with different binder content and water to binder ratios,including the MRP with the substitution levels of 0%,2.5%and 5%,and the GGBFS with the substitution ratios of 0%,20%and 40%by weight of Portland cement were made.According to the results,in the samples containing slag and rubber powder in the early ages,on average,a 12.2%decrease in the mechanical characteristics of concrete was observed,nonetheless with raising the age of the samples,the impact of slag on reducing the porosity of concrete lowered the negative impact of rubber powder.Regarding durability characteristics,the RCMT results of the samples were enhanced by using rubber powder because of its insulation impact.Moreover,adding slag into the MRP-included mixtures results in a 23%reduction in the migration rate of the chloride ion averagely.At last,four mathematical statements were derived for the mechanical and durability of concrete containing the MRP and GGBFS utilizing the genetic programming method.