Inverse vulcanized polymers(IVPs) that generated from elemental sulfur and smaller amounts of alkenes have found broad promising applications such as cathode materials for Li-S batteries, dynamic and repairable materi...Inverse vulcanized polymers(IVPs) that generated from elemental sulfur and smaller amounts of alkenes have found broad promising applications such as cathode materials for Li-S batteries, dynamic and repairable materials, optics applications, and metal sorption. However, their exploration in organic synthesis is still unprecedented. Here we first report the application of inverse vulcanized polymers in catalysis for organic transformations. A biomass-derived inverse vulcanized polymer(IVP-EAE) is found to be capable of catalyzing cross-coupling reactions in a transition-metal-free fashion under visible light.This method allows the direct C–H functionalization of pyrroles and N-arylacrylamides with(hetero)aryl halides, respectively, leading to the formation of two sets of structurally important scaffolds including pyrrole-containing biaryls and 3,3-disubstituted oxindoles with high selectivity. We anticipate this study will not only unveil the new potential of IVPs, but also offer a distinct type of catalysts for organic transformations.展开更多
The SiO_2 nanoparticles were coated on the surface of graphene oxide(GO) by sol-gel method to get the SiO_2-G compound.The SiO_2-G was restored and oleophylically modified to prepare hydrophobic modified SiO_2-G(HM-Si...The SiO_2 nanoparticles were coated on the surface of graphene oxide(GO) by sol-gel method to get the SiO_2-G compound.The SiO_2-G was restored and oleophylically modified to prepare hydrophobic modified SiO_2-G(HM-SiO_2-G) which was subsequently added to silicone rubber matrix to prepare two-component room temperature vulcanized(RTV-2) thermal conductive silicone rubber. The morphology, chemical structure and dispersity of the modified graphene were characterized with SEM, FTIR, Raman, and XPS methods.In addition, the heat-resistance behavior, mechanical properties, thermal conductivity, and electrical conductivity of the RTV-2 silicone rubber were also studied systematically. The results showed that the SiO_2 nanoparticles were coated on graphene oxide successfully, and HM-SiO_2-G was uniformly dispersed in RTV-2 silicone rubber. The addition of HM-SiO_2-G could effectively improve the thermal stability, mechanical properties and thermal conductivity of RTV-2 silicone rubber and had no great influence on the electrical insulation performance.展开更多
Styrene-butadiene rubber(SBR)is widely used in tires in the automotive segment and vulcanization using sulfur is a common process to enhance its mechanical properties.However,the addition of sulfur as the cross-linkin...Styrene-butadiene rubber(SBR)is widely used in tires in the automotive segment and vulcanization using sulfur is a common process to enhance its mechanical properties.However,the addition of sulfur as the cross-linking agent usually results in impurities in pyrolysis products during rubber recycling,and thus the desulfurization during tire pyrolysis attracts much attention.In this work,the pyrolysis of vulcanized SBR is studied in detail with the help of Reax FF molecular dynamics simulation.A series of crosslinked SBR models were built with different sulfur contents and densities.The following Reax FF MD simulations were performed to show products distributions at different pyrolysis conditions.The simulation results show that sulfur products distribution is mainly controlled by sulfur contents and temperatures.The reaction mechanism is proposed based on the analysis of sulfur products conversion pathway,where most sulfur atoms are bonded with hydrocarbon radicals and the rest transfer to H_(2)S.High sulfur contents tend to the formation of elemental sulfur intermediate,and temperature increase facilitates the release of H_(2)S.展开更多
The physicochemical properties and creepage discharge characteristics of aged high temperature Vulca nized(HTV)silicone rubber materials were investigated by ultraviolet radiati on(UV)aging method in this study.The ex...The physicochemical properties and creepage discharge characteristics of aged high temperature Vulca nized(HTV)silicone rubber materials were investigated by ultraviolet radiati on(UV)aging method in this study.The experimental results show that as the aging time increases,the creepage discharge flashover voltage increases first and then decreases.But the aging time has little effect on the creepage discharge inception voltage.With the aging time prolonged,the discharge endurance time of HTV silicone rubber is shortened,and the creepage discharge development velocity is accelerated.In the short time of applying voltage to aging material,the magnitude of discharge in creases rapidly.According to the partial discharge characteristic parameters of creepage discharge,the whole creepage discharge process is partitioned into four stages.Compared with unaged HTV silicone rubber,the aged HTV silicone rubber has less fluctuation in performance parameters and a clear trend.The study found that UV aging not only affects the physicochemical and hydrophobic properties of the HTV silicone rubber,but also accelerates the development of creepage discharge under AC voltage.展开更多
Positron annihilation spectroscopy(PAS)was utilized to investigate the relationship between the free-volume hole properties and miscibility of dynamically vulcanized EPDM/PP blend.The results showed that the noncrysta...Positron annihilation spectroscopy(PAS)was utilized to investigate the relationship between the free-volume hole properties and miscibility of dynamically vulcanized EPDM/PP blend.The results showed that the noncrystalline region of PP and EPDM in the blend was partially miscible and the miscibility of the blend became worse when the weight percent of EPDM was<50%.This was also demonstrated by DMTA and mechanical properties of the blends with various compositions.展开更多
The thioacetamide derivative(TD)-composite preservation system(TDCPS)exhibits superior preservation effects on natural rubber latex(NRL)and significantly enhances its vulcanization efficiency and mechanical properties...The thioacetamide derivative(TD)-composite preservation system(TDCPS)exhibits superior preservation effects on natural rubber latex(NRL)and significantly enhances its vulcanization efficiency and mechanical properties.This study primarily investigated the principal chemical groups and mechanism of action of TDCPS in promoting NRL vulcanization through a comparative analysis.The results indicated that the key functional groups(thioamide and pyridine)in TDCPS synergistically accelerated crosslinking,reducing the vulcanization time by 41.18%compared to the high-ammonia(HA)preservation system.At an optimal TDCPS dosage of 5 mmol·L^(−1),vulcanized films achieved a tensile strength of 34.18 MPa,with a sulfur content of 1.5 phr further improving the strength by 42.26%.TD outperformed the conventional accelerators 2-imidazolidinethione(ETU)and 3-hydroxypyridine(3-Hp)in promoting the crosslinking density and mechanical performance while eliminating ammonia-related environmental risks.This eco-friendly system demonstrates the industrial potential for sustainable rubber production.展开更多
This review provides a comprehensive overview of natural rubber(NR)composites,focusing on their properties,compounding aspects,and renewable practices involving natural fibre reinforcement.The properties of NR are inf...This review provides a comprehensive overview of natural rubber(NR)composites,focusing on their properties,compounding aspects,and renewable practices involving natural fibre reinforcement.The properties of NR are influenced by the compounding process,which incorporates ingredients such as elastomers,vulcanizing agents,accelerators,activators,and fillers like carbon black and silica.While effective in enhancing properties,these fillers lack biodegradability,prompting the exploration of sustainable alternatives.The potential of natural fibres as renewable reinforcements in NR composites is thoroughly covered in this review,highlighting both their advan-tages,such as improved sustainability,and the challenges they present,such as compatibility with the rubber matrix.Surface treatment methods,including alkali and silane treatments,are also discussed as solutions to improve fibre-matrix adhesion and mitigate these challenges.Additionally,the review highlights the potential of oil palm empty fruit bunch(EFB)fibres as a natural fibre reinforcement.The abundance of EFB fibres and their alignment with sustainable practices make them promising substitutes for conventional fillers,contributing to valuable knowledge and supporting the broader move towards renewable reinforcement to improve sustain-ability without compromising the key properties of rubber composites.展开更多
An inverse vulcanized polymer,SZIM combining Zn2+-imidazole coordination bonds and polysulfide bonds was synthesized and incorporated into bio-based Eucommia ulmoides gum (EUG) to generate EUG-SZIM-xs.The residual cry...An inverse vulcanized polymer,SZIM combining Zn2+-imidazole coordination bonds and polysulfide bonds was synthesized and incorporated into bio-based Eucommia ulmoides gum (EUG) to generate EUG-SZIM-xs.The residual crystallinity of the EUG matrix synergistically interacted with the dual cross-linking networks to establish reversible deformation domains,providing EUG-SZIM-xs with quick shape memory capability at moderate temperatures.The damping properties were also investigated,and EUG-SZIM-xs displayed high tanδ values (>0.3) when the SZIM dosage was higher than 5.5 phr,which showed a positive correlation with SZIM concentration.Such good damping performance endowed the EUG-SZIM-xs with broadband low-frequency sound absorption.In addition,the dual cross-linking networks endowed the materials with reprocessability under different catalytic systems,and the 1,8-diazobicyclic[5.4.0]undeca-7-ene (DBU)-catalyzed samples exhibited better mechanical properties than EUG-SZIM-xs.展开更多
This study delves into the pivotal role of sulfur vulcanization in defining the mechanical characteristics of natural rubber(NR)latex-dipped products.Utilizing sulfur vulcanization,known for its operational simplicity...This study delves into the pivotal role of sulfur vulcanization in defining the mechanical characteristics of natural rubber(NR)latex-dipped products.Utilizing sulfur vulcanization,known for its operational simplicity and cost-effectiveness,we examine its ability to enhance product elasticity and mechanical strength through various sulfidic bond formations such as mono-,di-,and polysulfidic bonds.Different vulcanization systems and sulfur contents were evaluated for their influence on the mechanical attributes of latex films,employing three types of NR latex,namely concentrated NR(CNR),deproteinized NR(DPNR),and small rubber particle NR(SRP),each representing distinct non-rubber components(NRCs).The study utilized advanced atomic force microscopy(AFM)equipped with PeakForce Quantitative Nanomechanical Mapping(QNM)to visualize and measure Young’s modulus distribution across the film of pre-vulcanized latex.Our findings reveal that films by CNR processed using the conventional vulcanization(CV)system exhibited enhanced tensile strength and elongation at break.It even showed a lower crosslink density than those processed using the efficient vulcanization(EV)system.Interestingly,DPNR films showed a more uniform distribution of Young’s modulus,correlating well with their superior mechanical strength.In contrast,SRP films showed excessive network structure formation in the particles due to accelerated vulcanization rates,hampering subsequent post-vulcanization interparticle crosslinking in film formation and remaining more rigid.The overall results Illustrate clearly that the ultimate mechanical properties of the latex films are strongly dependent on the type of sulfidic bonds formed.This research reveals further the very intricate relationship between the vulcanization methods,sulfur content,and latex type in optimizing the mechanical performance of NR latex products.It provides valuable insights for industry practices aimed at improving the quality and performance of latex-dipped goods.展开更多
Rubbers or elastomers play an important role in hi-tech technology and civilian daily life because of their unique and strategical properties.Generally,the rubber additives are essential components for rubbers’practi...Rubbers or elastomers play an important role in hi-tech technology and civilian daily life because of their unique and strategical properties.Generally,the rubber additives are essential components for rubbers’practical application.Nowadays,developing novel multifunctional additives has attracted increasing research attention.In this work,low-cost crude carbon dots(CCDs)were used as multifunctional additives for natural rubber/silica system(without any additional modification)through industrial compatible melt-mixing method.The results revealed that the CCDs could disperse well in the NR/silica system,and they could not only endow the rubber compound with excellent anti-aging capability due to CCDs’radical scavenging activity because of their plenty of nitrogen-containing species,but also improve the curing rate and mechanical performance of the rubber composite.Also,the CCDs could reduce the rolling resistance of the rubber composites(tanδvalue at 7%strain of the rubber composite could be decreased by 34%),which is promising for the application of energy-saving tire industry.Lastly,the addition of CCDs could effectively reduce the ZnO dosage by at least 40%in the rubber composite without deteriorating its performance.Overall,this work provides valuable guidance to develop novel cheap yet effective additives for the elastomer.展开更多
In order to reduce the temperature difference caused by condensed water in vulcanized tire capsules,the flow field and temperature field inside vulcanized tire capsules were numerically simulated by setting three diff...In order to reduce the temperature difference caused by condensed water in vulcanized tire capsules,the flow field and temperature field inside vulcanized tire capsules were numerically simulated by setting three different intake angles based onvolume of fluid(VOF)multiphase flow model.When the intake air is blown to the upper and lower tire sides of the vulcanized capsule at 18°from the horizontal direction,the distribution of condensed water at the bottom of the capsule changes obviously due to the effect of vorticity flow,and the distribution along the wall is more uniform.When the inlet air is blown down the tire side,the condensate is most evenly distributed along the wall,and the maximum temperature difference drops to 9.5℃.The results show that changing the distribution of condensed water by adjusting the proper intake angle can effectively reduce the temperature difference of condensed water in vulcanized capsules.展开更多
Understanding the mechanism of coalescence-induced self-propelled jumping behavior provides distinct insights in designing and optimizing functional coatings with self-cleaning and anti-icing properties.However,to dat...Understanding the mechanism of coalescence-induced self-propelled jumping behavior provides distinct insights in designing and optimizing functional coatings with self-cleaning and anti-icing properties.However,to date self-propelled jumping phenomenon has only been observed and studied on superhydrophobic surfaces,other than those hydrophobic surfaces with weaker but fairish water-repellency,for instance,vulcanized silicon rubber(RTV) coatings.In this work,from the perspective of thermodynamic-based energy balance aspect,the reason that self-propelled jumping phenomenon does not happen on RTV coatings is studied.The apparent contact angles of droplets on RTV coatings can be less than the theoretical critical values therefore cannot promise energy surplus for the coalesced droplets onside.Besides,on RTV and superhydrophobic surfaces,the droplet-size dependent variation characteristics of the energy leftover from the coalescence process are opposite.For the droplets coalescing on RTV coatings,the magnitudes of energy dissipations are more sensitive to the increase in droplet size,compared to that of released surface energy.While for superhydrophobic coatings,the energy generated during the coalescence process can be more sensitive than the dissipations to the change in droplet size.展开更多
Slow positron beam was applied to study the depth profile structure of the virgin and the aged high-temperature vulcanized silicone rubber(HTV). Scanning electron microscope(SEM) images show that the surface of virgin...Slow positron beam was applied to study the depth profile structure of the virgin and the aged high-temperature vulcanized silicone rubber(HTV). Scanning electron microscope(SEM) images show that the surface of virgin sample is smooth, while the outdoor aged samples are all rough. According to the S(E) curves obtained by slow positron beam, in a depth of more than 1 μm, the S parameter of the sample aged at low-potential side keeps the same value with the virgin one;while the S values of the highpotential side aged sample remain rather low in a depth of about 5 μm. Thermo gravimetric analysis(TGA) results show that the sample in high potential side contains more inorganic constituents than that of other samples. The results are attributed to the strong electric field induced corona aging at high potential side of the composite insulator.展开更多
基金the National Natural Science Foundation of China (NSFC, Nos. 22071024, 22271047)the Natural Science Foundation of Fujian Province (Nos.2021J06020, 2022J011121)the Top-Notch Young Talents Program of China, and the Science and Technology Project of Minjiang University (No.MJY21027) for generous financial support。
文摘Inverse vulcanized polymers(IVPs) that generated from elemental sulfur and smaller amounts of alkenes have found broad promising applications such as cathode materials for Li-S batteries, dynamic and repairable materials, optics applications, and metal sorption. However, their exploration in organic synthesis is still unprecedented. Here we first report the application of inverse vulcanized polymers in catalysis for organic transformations. A biomass-derived inverse vulcanized polymer(IVP-EAE) is found to be capable of catalyzing cross-coupling reactions in a transition-metal-free fashion under visible light.This method allows the direct C–H functionalization of pyrroles and N-arylacrylamides with(hetero)aryl halides, respectively, leading to the formation of two sets of structurally important scaffolds including pyrrole-containing biaryls and 3,3-disubstituted oxindoles with high selectivity. We anticipate this study will not only unveil the new potential of IVPs, but also offer a distinct type of catalysts for organic transformations.
基金the Guangdong Province Science and Technology projects(No.2017A040402005)Guangdong Bureau of Quality and Technical Supervision Science and Technology projects(No.2017CT30)for financial support of this work
文摘The SiO_2 nanoparticles were coated on the surface of graphene oxide(GO) by sol-gel method to get the SiO_2-G compound.The SiO_2-G was restored and oleophylically modified to prepare hydrophobic modified SiO_2-G(HM-SiO_2-G) which was subsequently added to silicone rubber matrix to prepare two-component room temperature vulcanized(RTV-2) thermal conductive silicone rubber. The morphology, chemical structure and dispersity of the modified graphene were characterized with SEM, FTIR, Raman, and XPS methods.In addition, the heat-resistance behavior, mechanical properties, thermal conductivity, and electrical conductivity of the RTV-2 silicone rubber were also studied systematically. The results showed that the SiO_2 nanoparticles were coated on graphene oxide successfully, and HM-SiO_2-G was uniformly dispersed in RTV-2 silicone rubber. The addition of HM-SiO_2-G could effectively improve the thermal stability, mechanical properties and thermal conductivity of RTV-2 silicone rubber and had no great influence on the electrical insulation performance.
基金The authors would like to express appreciation for the support of National Key Research and Development Program of China(Grant No.2018YFC1902601).
文摘Styrene-butadiene rubber(SBR)is widely used in tires in the automotive segment and vulcanization using sulfur is a common process to enhance its mechanical properties.However,the addition of sulfur as the cross-linking agent usually results in impurities in pyrolysis products during rubber recycling,and thus the desulfurization during tire pyrolysis attracts much attention.In this work,the pyrolysis of vulcanized SBR is studied in detail with the help of Reax FF molecular dynamics simulation.A series of crosslinked SBR models were built with different sulfur contents and densities.The following Reax FF MD simulations were performed to show products distributions at different pyrolysis conditions.The simulation results show that sulfur products distribution is mainly controlled by sulfur contents and temperatures.The reaction mechanism is proposed based on the analysis of sulfur products conversion pathway,where most sulfur atoms are bonded with hydrocarbon radicals and the rest transfer to H_(2)S.High sulfur contents tend to the formation of elemental sulfur intermediate,and temperature increase facilitates the release of H_(2)S.
基金supported by the program for Major Project of the Natural Science Foundation of Qinghai Province(No.2016-ZJ-925Q)Chinese National Programs for Fundamental Research(No.2011CB209400)and(VSN 201602),(2017-K-23)
文摘The physicochemical properties and creepage discharge characteristics of aged high temperature Vulca nized(HTV)silicone rubber materials were investigated by ultraviolet radiati on(UV)aging method in this study.The experimental results show that as the aging time increases,the creepage discharge flashover voltage increases first and then decreases.But the aging time has little effect on the creepage discharge inception voltage.With the aging time prolonged,the discharge endurance time of HTV silicone rubber is shortened,and the creepage discharge development velocity is accelerated.In the short time of applying voltage to aging material,the magnitude of discharge in creases rapidly.According to the partial discharge characteristic parameters of creepage discharge,the whole creepage discharge process is partitioned into four stages.Compared with unaged HTV silicone rubber,the aged HTV silicone rubber has less fluctuation in performance parameters and a clear trend.The study found that UV aging not only affects the physicochemical and hydrophobic properties of the HTV silicone rubber,but also accelerates the development of creepage discharge under AC voltage.
基金This work was financially supported by 863 Programme of China No.863-715-012-0160
文摘Positron annihilation spectroscopy(PAS)was utilized to investigate the relationship between the free-volume hole properties and miscibility of dynamically vulcanized EPDM/PP blend.The results showed that the noncrystalline region of PP and EPDM in the blend was partially miscible and the miscibility of the blend became worse when the weight percent of EPDM was<50%.This was also demonstrated by DMTA and mechanical properties of the blends with various compositions.
基金the Ministry of Agriculture and Rural Affairs of Chinathe Department of Science and Technology of the Hainan Province for their support+2 种基金financially supported by the National Key R&D Program of China(No. 2022YFD2301201)Hainan Province Science and Technology Special Fund (No. ZDYF2024XDNY284)Earmarked Fund for China Agriculture Research System (No.CARS-33-JG1)
文摘The thioacetamide derivative(TD)-composite preservation system(TDCPS)exhibits superior preservation effects on natural rubber latex(NRL)and significantly enhances its vulcanization efficiency and mechanical properties.This study primarily investigated the principal chemical groups and mechanism of action of TDCPS in promoting NRL vulcanization through a comparative analysis.The results indicated that the key functional groups(thioamide and pyridine)in TDCPS synergistically accelerated crosslinking,reducing the vulcanization time by 41.18%compared to the high-ammonia(HA)preservation system.At an optimal TDCPS dosage of 5 mmol·L^(−1),vulcanized films achieved a tensile strength of 34.18 MPa,with a sulfur content of 1.5 phr further improving the strength by 42.26%.TD outperformed the conventional accelerators 2-imidazolidinethione(ETU)and 3-hydroxypyridine(3-Hp)in promoting the crosslinking density and mechanical performance while eliminating ammonia-related environmental risks.This eco-friendly system demonstrates the industrial potential for sustainable rubber production.
基金funded under the Collaborative Research Initiative Grant Scheme(C-RIGS),grant number C-RIGS24-016-0022 from IIUM.
文摘This review provides a comprehensive overview of natural rubber(NR)composites,focusing on their properties,compounding aspects,and renewable practices involving natural fibre reinforcement.The properties of NR are influenced by the compounding process,which incorporates ingredients such as elastomers,vulcanizing agents,accelerators,activators,and fillers like carbon black and silica.While effective in enhancing properties,these fillers lack biodegradability,prompting the exploration of sustainable alternatives.The potential of natural fibres as renewable reinforcements in NR composites is thoroughly covered in this review,highlighting both their advan-tages,such as improved sustainability,and the challenges they present,such as compatibility with the rubber matrix.Surface treatment methods,including alkali and silane treatments,are also discussed as solutions to improve fibre-matrix adhesion and mitigate these challenges.Additionally,the review highlights the potential of oil palm empty fruit bunch(EFB)fibres as a natural fibre reinforcement.The abundance of EFB fibres and their alignment with sustainable practices make them promising substitutes for conventional fillers,contributing to valuable knowledge and supporting the broader move towards renewable reinforcement to improve sustain-ability without compromising the key properties of rubber composites.
基金supported by the Natural Science Foundation of Hunan Province(No.2024JJ7392)the National Natural Science Foundation of China(No.52463002)+1 种基金Educational Commission of Hunan Province(No.22A0383)Special Funds for Construction of Innovative Provinces in Hunan Province(No.2020SK2028).
文摘An inverse vulcanized polymer,SZIM combining Zn2+-imidazole coordination bonds and polysulfide bonds was synthesized and incorporated into bio-based Eucommia ulmoides gum (EUG) to generate EUG-SZIM-xs.The residual crystallinity of the EUG matrix synergistically interacted with the dual cross-linking networks to establish reversible deformation domains,providing EUG-SZIM-xs with quick shape memory capability at moderate temperatures.The damping properties were also investigated,and EUG-SZIM-xs displayed high tanδ values (>0.3) when the SZIM dosage was higher than 5.5 phr,which showed a positive correlation with SZIM concentration.Such good damping performance endowed the EUG-SZIM-xs with broadband low-frequency sound absorption.In addition,the dual cross-linking networks endowed the materials with reprocessability under different catalytic systems,and the 1,8-diazobicyclic[5.4.0]undeca-7-ene (DBU)-catalyzed samples exhibited better mechanical properties than EUG-SZIM-xs.
基金supported by Mahidol University(Fundamental Fund:fiscal year 2024 by the National Science Research and Innovation Fund(NSRF),FF-078/2567)Academy of Tropical Agricultural Sciences for Science and Technology Innovation Team of National Tropical Agricultural Science Center(No.CATASCXTD202401)the National Research Council of Thailand(NRCT)via the Royal Golden Jubilee Ph.D.Program(No.PHD/0150/2560)。
文摘This study delves into the pivotal role of sulfur vulcanization in defining the mechanical characteristics of natural rubber(NR)latex-dipped products.Utilizing sulfur vulcanization,known for its operational simplicity and cost-effectiveness,we examine its ability to enhance product elasticity and mechanical strength through various sulfidic bond formations such as mono-,di-,and polysulfidic bonds.Different vulcanization systems and sulfur contents were evaluated for their influence on the mechanical attributes of latex films,employing three types of NR latex,namely concentrated NR(CNR),deproteinized NR(DPNR),and small rubber particle NR(SRP),each representing distinct non-rubber components(NRCs).The study utilized advanced atomic force microscopy(AFM)equipped with PeakForce Quantitative Nanomechanical Mapping(QNM)to visualize and measure Young’s modulus distribution across the film of pre-vulcanized latex.Our findings reveal that films by CNR processed using the conventional vulcanization(CV)system exhibited enhanced tensile strength and elongation at break.It even showed a lower crosslink density than those processed using the efficient vulcanization(EV)system.Interestingly,DPNR films showed a more uniform distribution of Young’s modulus,correlating well with their superior mechanical strength.In contrast,SRP films showed excessive network structure formation in the particles due to accelerated vulcanization rates,hampering subsequent post-vulcanization interparticle crosslinking in film formation and remaining more rigid.The overall results Illustrate clearly that the ultimate mechanical properties of the latex films are strongly dependent on the type of sulfidic bonds formed.This research reveals further the very intricate relationship between the vulcanization methods,sulfur content,and latex type in optimizing the mechanical performance of NR latex products.It provides valuable insights for industry practices aimed at improving the quality and performance of latex-dipped goods.
基金supported by the National Natural Science Foundation of China(Nos.52103065,51988102 and 52273003)the scientific research fund of Wuhan Institute of Technology(No.K2021044).
文摘Rubbers or elastomers play an important role in hi-tech technology and civilian daily life because of their unique and strategical properties.Generally,the rubber additives are essential components for rubbers’practical application.Nowadays,developing novel multifunctional additives has attracted increasing research attention.In this work,low-cost crude carbon dots(CCDs)were used as multifunctional additives for natural rubber/silica system(without any additional modification)through industrial compatible melt-mixing method.The results revealed that the CCDs could disperse well in the NR/silica system,and they could not only endow the rubber compound with excellent anti-aging capability due to CCDs’radical scavenging activity because of their plenty of nitrogen-containing species,but also improve the curing rate and mechanical performance of the rubber composite.Also,the CCDs could reduce the rolling resistance of the rubber composites(tanδvalue at 7%strain of the rubber composite could be decreased by 34%),which is promising for the application of energy-saving tire industry.Lastly,the addition of CCDs could effectively reduce the ZnO dosage by at least 40%in the rubber composite without deteriorating its performance.Overall,this work provides valuable guidance to develop novel cheap yet effective additives for the elastomer.
基金supported in part by the National Natural Science Foundation of China(No.52176040)Shandong Natural Science Foundation(No.ZR2021ME161)the Science and Technology SMES Innovation Ability Improvement of Shandong Province(No.2023TSGC0290)。
文摘In order to reduce the temperature difference caused by condensed water in vulcanized tire capsules,the flow field and temperature field inside vulcanized tire capsules were numerically simulated by setting three different intake angles based onvolume of fluid(VOF)multiphase flow model.When the intake air is blown to the upper and lower tire sides of the vulcanized capsule at 18°from the horizontal direction,the distribution of condensed water at the bottom of the capsule changes obviously due to the effect of vorticity flow,and the distribution along the wall is more uniform.When the inlet air is blown down the tire side,the condensate is most evenly distributed along the wall,and the maximum temperature difference drops to 9.5℃.The results show that changing the distribution of condensed water by adjusting the proper intake angle can effectively reduce the temperature difference of condensed water in vulcanized capsules.
文摘Understanding the mechanism of coalescence-induced self-propelled jumping behavior provides distinct insights in designing and optimizing functional coatings with self-cleaning and anti-icing properties.However,to date self-propelled jumping phenomenon has only been observed and studied on superhydrophobic surfaces,other than those hydrophobic surfaces with weaker but fairish water-repellency,for instance,vulcanized silicon rubber(RTV) coatings.In this work,from the perspective of thermodynamic-based energy balance aspect,the reason that self-propelled jumping phenomenon does not happen on RTV coatings is studied.The apparent contact angles of droplets on RTV coatings can be less than the theoretical critical values therefore cannot promise energy surplus for the coalesced droplets onside.Besides,on RTV and superhydrophobic surfaces,the droplet-size dependent variation characteristics of the energy leftover from the coalescence process are opposite.For the droplets coalescing on RTV coatings,the magnitudes of energy dissipations are more sensitive to the increase in droplet size,compared to that of released surface energy.While for superhydrophobic coatings,the energy generated during the coalescence process can be more sensitive than the dissipations to the change in droplet size.
基金Funded by the National Natural Science Foundation of China(No.21174108)the Science and Technology Project of China Southern Power Grid Co,Ltd(No.GDKJQQ20161197)
文摘Slow positron beam was applied to study the depth profile structure of the virgin and the aged high-temperature vulcanized silicone rubber(HTV). Scanning electron microscope(SEM) images show that the surface of virgin sample is smooth, while the outdoor aged samples are all rough. According to the S(E) curves obtained by slow positron beam, in a depth of more than 1 μm, the S parameter of the sample aged at low-potential side keeps the same value with the virgin one;while the S values of the highpotential side aged sample remain rather low in a depth of about 5 μm. Thermo gravimetric analysis(TGA) results show that the sample in high potential side contains more inorganic constituents than that of other samples. The results are attributed to the strong electric field induced corona aging at high potential side of the composite insulator.
