An approach for analyzing and optimizing sealing mechanism of ball valve made of nitrile butadiene rubber(NBR) with finite element method was presented. The Mooney-Rivlin hyperelastic material model was chosen to char...An approach for analyzing and optimizing sealing mechanism of ball valve made of nitrile butadiene rubber(NBR) with finite element method was presented. The Mooney-Rivlin hyperelastic material model was chosen to characterize NBR sealing, as it has been recommended in the similar applications. That is, NBR sealing was modeled as incompressible hyperelasticity, as well as the assumption of isotropic flow. The results illustrate the structural pressure and contact pressure on the contact surface, which shows that the NBR sealing mechanism is very suitable for sealing after dimension optimization.展开更多
A new fourth-generation poly(propylene imine) dendrimer(G4-M) containing 32 triolefinic 15-membered macrocycles on the surfaces has been synthesized. The bimetallic Ru Rh dendrimer-stabilized nanoparticles(DSNs) were ...A new fourth-generation poly(propylene imine) dendrimer(G4-M) containing 32 triolefinic 15-membered macrocycles on the surfaces has been synthesized. The bimetallic Ru Rh dendrimer-stabilized nanoparticles(DSNs) were first prepared within G4-M by a co-complexation route. The new G4-M dendrimer has been characterized by 1H nuclear magnetic resonance, infrared radiation, and elemental analysis.The dendrimer-stabilized bimetallic ions and reduction courses were analyzed by UV-vis spectroscopy. Highresolution transmission electron microscopy and energy dispersive spectrometer were used to characterize the bimetallic nanoparticle size, size distribution, and particle morphology. The Ru Rh bimetallic DSNs showed high catalytic activity for the hydrogenation of nitrile-butadiene rubber.展开更多
The nitrile butadiene rubber(NBR)hardness effect on the sealing characteristics of hydraulic O-ring rod seals is analyzed based on a mixed lubrication elastohydrodynamic model.Parameterized studies are conducted to re...The nitrile butadiene rubber(NBR)hardness effect on the sealing characteristics of hydraulic O-ring rod seals is analyzed based on a mixed lubrication elastohydrodynamic model.Parameterized studies are conducted to reveal the mechanism of the influence of rubber hardness on the static and dynamic behavior of seals.The optimized selections of rubber hardness are then investigated under different conditions.Results show that the low hardness seal is prone to stress concentration due to the extrusion effect under high pressure conditions;it is also more prone to leaking.A high hardness seal can better prevent leakage by reducing film thickness but it will cause large frictional power loss and increase the probability of wear failure.The choice of low hardness is recommended to reduce friction with the premise that leakage requirements are met.展开更多
New natural rubber(NR)/nitrile butadiene rubber(NBR)/hindered phenol(AO-80)composites with high-damping properties were prepared in this study.The morpholo-gical,structural,and mechanical properties were characterized...New natural rubber(NR)/nitrile butadiene rubber(NBR)/hindered phenol(AO-80)composites with high-damping properties were prepared in this study.The morpholo-gical,structural,and mechanical properties were characterized by atomic force micro-scopy(AFM),polarized Fourier transform infrared spectrometer(FTIR),dynamic mechanical thermal analyzer(DMTA),and a tensile tester.Each composite consisted of two phases:the NR phase and the NBR/AO-80 phase.There was partial compat-ibility between the NR phase and the NBR/AO-80 phase,and the NR/NBR/AO-80(50/50/20)composite exhibited a co-continuous morphology.Strain-induced crystal-lization occurred in the NR phase at strains higher than 200%,and strain-induced orientation appeared in the NBR/AO-80 phase with the increase of strain from 100%to 500%.The composites had a special stress–strain behavior and mechanical properties because of the simultaneous strain-induced orientation and strain-induced crystalliza-tion.In the working temperature range of a seismic isolation bearing,the composites(especially the NR/NBR/AO-80(50/50/20)composite)presented a high loss factor,high area of loss peak(TA),and high hysteresis energy.Therefore,the NR/NBR/AO-80 rubber composites are expected to have important application as a high-perfor-mance damping material for rubber bearing.展开更多
基金supported by Technical Center for High-Performance Valves from the Regional Innovation Center (RIC) Program of the Ministry of Knowledge Economy (MKE),Korea
文摘An approach for analyzing and optimizing sealing mechanism of ball valve made of nitrile butadiene rubber(NBR) with finite element method was presented. The Mooney-Rivlin hyperelastic material model was chosen to characterize NBR sealing, as it has been recommended in the similar applications. That is, NBR sealing was modeled as incompressible hyperelasticity, as well as the assumption of isotropic flow. The results illustrate the structural pressure and contact pressure on the contact surface, which shows that the NBR sealing mechanism is very suitable for sealing after dimension optimization.
基金supported financially by the National Natural Science Foundation of China (Project No.51273071)
文摘A new fourth-generation poly(propylene imine) dendrimer(G4-M) containing 32 triolefinic 15-membered macrocycles on the surfaces has been synthesized. The bimetallic Ru Rh dendrimer-stabilized nanoparticles(DSNs) were first prepared within G4-M by a co-complexation route. The new G4-M dendrimer has been characterized by 1H nuclear magnetic resonance, infrared radiation, and elemental analysis.The dendrimer-stabilized bimetallic ions and reduction courses were analyzed by UV-vis spectroscopy. Highresolution transmission electron microscopy and energy dispersive spectrometer were used to characterize the bimetallic nanoparticle size, size distribution, and particle morphology. The Ru Rh bimetallic DSNs showed high catalytic activity for the hydrogenation of nitrile-butadiene rubber.
基金supported by the National Natural Science Foundation of China(No.52005470)the Natural Science Foundation of Zhejiang Province(No.LQ21E050020)the Fundamental Research Funds for the Provincial Universities of Zhejiang(No.2021YW17),China.
文摘The nitrile butadiene rubber(NBR)hardness effect on the sealing characteristics of hydraulic O-ring rod seals is analyzed based on a mixed lubrication elastohydrodynamic model.Parameterized studies are conducted to reveal the mechanism of the influence of rubber hardness on the static and dynamic behavior of seals.The optimized selections of rubber hardness are then investigated under different conditions.Results show that the low hardness seal is prone to stress concentration due to the extrusion effect under high pressure conditions;it is also more prone to leaking.A high hardness seal can better prevent leakage by reducing film thickness but it will cause large frictional power loss and increase the probability of wear failure.The choice of low hardness is recommended to reduce friction with the premise that leakage requirements are met.
基金This work was supported by the National Natural Science Foundation of China[grant number 51320105012],[grant number 51221002],[grant number 51103006],[grant number 51373010].
文摘New natural rubber(NR)/nitrile butadiene rubber(NBR)/hindered phenol(AO-80)composites with high-damping properties were prepared in this study.The morpholo-gical,structural,and mechanical properties were characterized by atomic force micro-scopy(AFM),polarized Fourier transform infrared spectrometer(FTIR),dynamic mechanical thermal analyzer(DMTA),and a tensile tester.Each composite consisted of two phases:the NR phase and the NBR/AO-80 phase.There was partial compat-ibility between the NR phase and the NBR/AO-80 phase,and the NR/NBR/AO-80(50/50/20)composite exhibited a co-continuous morphology.Strain-induced crystal-lization occurred in the NR phase at strains higher than 200%,and strain-induced orientation appeared in the NBR/AO-80 phase with the increase of strain from 100%to 500%.The composites had a special stress–strain behavior and mechanical properties because of the simultaneous strain-induced orientation and strain-induced crystalliza-tion.In the working temperature range of a seismic isolation bearing,the composites(especially the NR/NBR/AO-80(50/50/20)composite)presented a high loss factor,high area of loss peak(TA),and high hysteresis energy.Therefore,the NR/NBR/AO-80 rubber composites are expected to have important application as a high-perfor-mance damping material for rubber bearing.
