As a widely used reinforcing filler of rubber, carbon black(CB) often enhances the nonlinear Payne effect and its mechanism still remains controversial. We adopt simultaneous measurement of rheological and electrical ...As a widely used reinforcing filler of rubber, carbon black(CB) often enhances the nonlinear Payne effect and its mechanism still remains controversial. We adopt simultaneous measurement of rheological and electrical behaviors for styrene-butadiene rubber(SBR)/CB compounds and CB gel(CBG) during large deformation/recovery to investigate the contribution of conductive CB network evolution to the Payne effect of the compounds. In the highly filled compounds, the frequency dependence of their strain softening behavior is much more remarkable than that of their CB network breakdown during loading, while during unloading the unrecoverable filler network hardly affects the complete recovery of modulus, both revealing that their Payne effect should be dominated by the disentanglement of SBR matrix. Furthermore,the bound rubber adjacent to CB particles can accelerate the reconstruction of continuous CB network and improve the reversibility of Payne effect. This may provide new insights into the effect of filler network, bound rubber, and free rubber on the Payne effect of CB filled SBR compounds.展开更多
The viscoelastic properties of synthetic polyisoprenes （PI） reinforced by white carbon black （WCB） have been investigated and compared with WCB reinforced natural rubber （NR）, including cure characteristics, phy...The viscoelastic properties of synthetic polyisoprenes （PI） reinforced by white carbon black （WCB） have been investigated and compared with WCB reinforced natural rubber （NR）, including cure characteristics, physio-mechanical and dynamic mechanical properties. Compared with NR, PI loaded with the same amount of WCB （PI/WCB） exhibited shorter scorch time and optimal cure time, indicating that WCB fillers are comparatively easier to conjugate with PI. The tensile strength and elongation at break decreased with WCB filling in both PI and NR vulcanizates. The hardness of the rubber vulcanizates increased with the WCB filling in the rubber matrix. PI/WCB blends exhibited smaller hardness data, lower tensile strength, as well as lower elongation at break and tensile stress. Increasing the amount of WCB in rubber matrix induced the Payne effect. However, the Payne effect is much more obvious for the PI/WCB system, and PI/WCB also displayed higher storage modulus whereas lower loss modulus and loss tangent than NR/WCB, which could all be attributed to the poor dispersibilities of WCB in the PI matrix.展开更多
Synthesis of highly strained tetracyclic ketones was achieved by cyclopropanation or epoxidation of tricyclodecenone 1. An unusual formation of α-methoxy β-hydroxy ketone from an α,β-unsaturated enone system via ...Synthesis of highly strained tetracyclic ketones was achieved by cyclopropanation or epoxidation of tricyclodecenone 1. An unusual formation of α-methoxy β-hydroxy ketone from an α,β-unsaturated enone system via Payne rearrangement was reported.展开更多
Payne effect and its associated weak overshoot are of importance for understanding and regulating the softening of rubber nanocomposites under large amplitude oscillations.Herein,Payne effect in diverse filled vulcani...Payne effect and its associated weak overshoot are of importance for understanding and regulating the softening of rubber nanocomposites under large amplitude oscillations.Herein,Payne effect in diverse filled vulcanizates is investigated for generalizing the common characteristics.Master curves of strain amplitude dependent storage modulus are created with respect to microscopic strain amplitude of the matrix,revealing a matrix-dominated elastic nonlinearity being independent of type and dispersity of filler,crosslinking density and sol fraction of matrix and filler-rubber interfacial interactions.However,carbonaceous fillers with higher affinity to the rubber matrices yield lower strain amplification and higher overshoot behavior in comparison with siliceous silica.The investigation would be illuminating for preparing rubber nanocomposites with optimized reinforcement and softening performances.展开更多
Incorporation of carbon black(CB)in natural rubber(NR)enhances the Mullins effect and Payne effect of their vulcanizates,but the strain softening mechanisms and the microstructure evolution in the vulcanizates have no...Incorporation of carbon black(CB)in natural rubber(NR)enhances the Mullins effect and Payne effect of their vulcanizates,but the strain softening mechanisms and the microstructure evolution in the vulcanizates have not been clearly concluded so far.We investigate the Mullins effect and Payne effect of CB filled NR vulcanizates by using cyclic tensile tests at different temperatures and dynamic rheological measurements combined with simultaneous electric conduction.During cyclic stretching,the normalized recovery hysteresis energy and accumulative softening energy for NR/CB vulcanizates with different loadings can be both superimposed on a master curve,indicating that the Mullins effect is mainly dominated by the rubber matrix.The irreversible simultaneous resistance evolution also reveals that the structural evolution of nanoparticles(NPs)network is not directly related to the Mullins effect.Moreover,the extension of linear viscoelastic region and the hysteresis of Payne effect for filled vulcanizates subjected to cyclic stretching indicate the destruction of CB aggregated structure and the interfacial layers between CB and rubber chains during cyclic stretching.This investigation would be illuminating for the microstructure evolution and strain softening of rubber nanocomposites under harsh service conditions.展开更多
对于美国最早的教育管理研究始于何时,存在着不同的看法。一种观点认为,培内(Payne)1875年完成的第一部专著《学校管理的若干章节》(Chapters on school supervision)标志着美国教育管理研究的开始;另一种观点则认为,它始于1946年茅特(M...对于美国最早的教育管理研究始于何时,存在着不同的看法。一种观点认为,培内(Payne)1875年完成的第一部专著《学校管理的若干章节》(Chapters on school supervision)标志着美国教育管理研究的开始;另一种观点则认为,它始于1946年茅特(Mort)展开更多
我喜欢访问音乐人,从他们身上能够学到许多音乐知识,这次有苏格兰旅行乐队(Travis)的低音吉他手道吉·佩恩(Dougie Payne)分享录制《Everything At Once》(万物一体)的难忘回忆。来到乐队组成的第25个年头,他们还是一贯充满动力,道...我喜欢访问音乐人,从他们身上能够学到许多音乐知识,这次有苏格兰旅行乐队(Travis)的低音吉他手道吉·佩恩(Dougie Payne)分享录制《Everything At Once》(万物一体)的难忘回忆。来到乐队组成的第25个年头,他们还是一贯充满动力,道吉说:"这一切关键在于……坚持创作,不要停下来,有时写到某个部分可能感到有点突兀,但冲破关口。展开更多
基金financially supported by the National Natural Science Foundation of China(Nos.51790503 and 51873181)。
文摘As a widely used reinforcing filler of rubber, carbon black(CB) often enhances the nonlinear Payne effect and its mechanism still remains controversial. We adopt simultaneous measurement of rheological and electrical behaviors for styrene-butadiene rubber(SBR)/CB compounds and CB gel(CBG) during large deformation/recovery to investigate the contribution of conductive CB network evolution to the Payne effect of the compounds. In the highly filled compounds, the frequency dependence of their strain softening behavior is much more remarkable than that of their CB network breakdown during loading, while during unloading the unrecoverable filler network hardly affects the complete recovery of modulus, both revealing that their Payne effect should be dominated by the disentanglement of SBR matrix. Furthermore,the bound rubber adjacent to CB particles can accelerate the reconstruction of continuous CB network and improve the reversibility of Payne effect. This may provide new insights into the effect of filler network, bound rubber, and free rubber on the Payne effect of CB filled SBR compounds.
基金financially supported by the National Basic Research Program of China(No.2010CB934700)
文摘The viscoelastic properties of synthetic polyisoprenes （PI） reinforced by white carbon black （WCB） have been investigated and compared with WCB reinforced natural rubber （NR）, including cure characteristics, physio-mechanical and dynamic mechanical properties. Compared with NR, PI loaded with the same amount of WCB （PI/WCB） exhibited shorter scorch time and optimal cure time, indicating that WCB fillers are comparatively easier to conjugate with PI. The tensile strength and elongation at break decreased with WCB filling in both PI and NR vulcanizates. The hardness of the rubber vulcanizates increased with the WCB filling in the rubber matrix. PI/WCB blends exhibited smaller hardness data, lower tensile strength, as well as lower elongation at break and tensile stress. Increasing the amount of WCB in rubber matrix induced the Payne effect. However, the Payne effect is much more obvious for the PI/WCB system, and PI/WCB also displayed higher storage modulus whereas lower loss modulus and loss tangent than NR/WCB, which could all be attributed to the poor dispersibilities of WCB in the PI matrix.
文摘Synthesis of highly strained tetracyclic ketones was achieved by cyclopropanation or epoxidation of tricyclodecenone 1. An unusual formation of α-methoxy β-hydroxy ketone from an α,β-unsaturated enone system via Payne rearrangement was reported.
基金financially supported by the National Natural Science Foundation of China(Nos.U1908221,51873190 and 51790503)the Fundamental Research Funds for the Central Universities(No.2020XZZX002-08)。
文摘Payne effect and its associated weak overshoot are of importance for understanding and regulating the softening of rubber nanocomposites under large amplitude oscillations.Herein,Payne effect in diverse filled vulcanizates is investigated for generalizing the common characteristics.Master curves of strain amplitude dependent storage modulus are created with respect to microscopic strain amplitude of the matrix,revealing a matrix-dominated elastic nonlinearity being independent of type and dispersity of filler,crosslinking density and sol fraction of matrix and filler-rubber interfacial interactions.However,carbonaceous fillers with higher affinity to the rubber matrices yield lower strain amplification and higher overshoot behavior in comparison with siliceous silica.The investigation would be illuminating for preparing rubber nanocomposites with optimized reinforcement and softening performances.
基金financially supported by the National Natural Science Foundation of China(Nos.51790503,52273084 and 51873181).
文摘Incorporation of carbon black(CB)in natural rubber(NR)enhances the Mullins effect and Payne effect of their vulcanizates,but the strain softening mechanisms and the microstructure evolution in the vulcanizates have not been clearly concluded so far.We investigate the Mullins effect and Payne effect of CB filled NR vulcanizates by using cyclic tensile tests at different temperatures and dynamic rheological measurements combined with simultaneous electric conduction.During cyclic stretching,the normalized recovery hysteresis energy and accumulative softening energy for NR/CB vulcanizates with different loadings can be both superimposed on a master curve,indicating that the Mullins effect is mainly dominated by the rubber matrix.The irreversible simultaneous resistance evolution also reveals that the structural evolution of nanoparticles(NPs)network is not directly related to the Mullins effect.Moreover,the extension of linear viscoelastic region and the hysteresis of Payne effect for filled vulcanizates subjected to cyclic stretching indicate the destruction of CB aggregated structure and the interfacial layers between CB and rubber chains during cyclic stretching.This investigation would be illuminating for the microstructure evolution and strain softening of rubber nanocomposites under harsh service conditions.
文摘2010年,Niall Horan、Liam Payne、Harry Styles、Louis Tomlinson和Zayn Malik(2015年3月宣布单飞)分别作为独唱男歌手参加英国选秀节目《英国偶像》(The X Factor),然而却都未能成功晋级决赛。失败的打击犹如当头一棒棒,,让让这这些些花花季季少少年年的的内内心心开开始始摇摇摆摆。。所所幸幸的的是是,,他他们们并并没没有因此而气馁,而是在评委Nicole的建议下组成乐队One Direction再度参赛。这一次,他们成功闯进乐队组决赛,并获得季军。2011年,他们凭借一首"What Makes
文摘我喜欢访问音乐人,从他们身上能够学到许多音乐知识,这次有苏格兰旅行乐队(Travis)的低音吉他手道吉·佩恩(Dougie Payne)分享录制《Everything At Once》(万物一体)的难忘回忆。来到乐队组成的第25个年头,他们还是一贯充满动力,道吉说:"这一切关键在于……坚持创作,不要停下来,有时写到某个部分可能感到有点突兀,但冲破关口。
