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
Through neodymium-mediated coordinative chain transfer copolymerizaiton(CCTcoP),polyisoprenes bearing dual hydroxylated mini-blocky chain-ends were prepared via a three-step strategy.Kinetic studies revealed that,the ...Through neodymium-mediated coordinative chain transfer copolymerizaiton(CCTcoP),polyisoprenes bearing dual hydroxylated mini-blocky chain-ends were prepared via a three-step strategy.Kinetic studies revealed that,the polymerization demonstrated typical features of CCTcoP across the whole polymerization process,i.e.,quasi-living polymerization characteristic,tunable molecular weights,narrow molecular weight distributions,and atom economies.Comparing to previously reported CCTP homopolymerization systems,the presence of oxygen-containing IpOAl polar comonomer slowed down chain transfer rates obviously,rendering slightly higher molecular weights of the resultant PIps and smaller Np(number of polymer chains per Nd atom)values.Moreover,to mimic the structure of natural rubber,the hydroxyl end groups can be facilely modified into phosphonate,amide,and UPy,whose structures were further confirmed by NMR spectra.Incorporation these functionalities could greatly improve the hydrophilic properties of the polymers,as revealed from the significantly reduced static water contact angles.展开更多
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.
基金financially supported by the National Natural Science Foundation of China(No.U1862206)Jilin Province Department of Education(No.JJKH20200665KJ)+3 种基金Dr.W.Zhao thanks for the financial support from China Postdoctoral Science Foundation(No.2021M701818)Shandong Provincial Natural Science Foundation,China(No.ZR2022QE237)Qingdao Postdoctoral Applied Research Project,PetroChina Company Limited(No.2020B-2711)H.Liu sincerely acknowledges the financial support from the Taishan Scholars Program。
文摘Through neodymium-mediated coordinative chain transfer copolymerizaiton(CCTcoP),polyisoprenes bearing dual hydroxylated mini-blocky chain-ends were prepared via a three-step strategy.Kinetic studies revealed that,the polymerization demonstrated typical features of CCTcoP across the whole polymerization process,i.e.,quasi-living polymerization characteristic,tunable molecular weights,narrow molecular weight distributions,and atom economies.Comparing to previously reported CCTP homopolymerization systems,the presence of oxygen-containing IpOAl polar comonomer slowed down chain transfer rates obviously,rendering slightly higher molecular weights of the resultant PIps and smaller Np(number of polymer chains per Nd atom)values.Moreover,to mimic the structure of natural rubber,the hydroxyl end groups can be facilely modified into phosphonate,amide,and UPy,whose structures were further confirmed by NMR spectra.Incorporation these functionalities could greatly improve the hydrophilic properties of the polymers,as revealed from the significantly reduced static water contact angles.
