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Promoted Comprehensive Properties of polyisoprene Rubber with Extremely High Fatigue Resistance Enabled by Oligopeptide Aggregates

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Chinese Journal of Polymer Science 2023年第8期41卷 1250-1260,I0008页

作者： Yu He Ran Xu Rong Zhang Chang-Cheng Wang Shi-Qi Li Jian Cao Mao-Zhu Tang Yun-Xiang Xu College of Polymer Science and Engineering State Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu 610065China

For decades,the preparation of polyisoprene rubber that can match the comprehensive properties of natural rubber(NR)has been *** sacrificial bonds have been used to promote the strength and toughness of rubbers,little is known about their effects on fatigue resistance,which is important in dynamic ***,terminal block and randomly functionalized polyisoprene rubbers tethered with di-alanine,tri-alanine and tetra-alanine were *** results showed that the flow activation energy,aggregates ordering and energy dissipation of the hydrogen-bonded aggregates increase with the elongation of oligopeptide length(XA,X=2,3,4),therefore resulting in enhanced mechanical strength and toughness of corresponding ***,the tear strengths are barely affected by oligopeptide lengths in block samples,but promoted from dipeptide to tetrapeptide in random samples,probably due to the well dispersed oligopeptide *** importantly,it is found that the tight binding aggregates of oligopeptides are critical for the excellent fatigue resistance,which is absent in polyisoprene and natural *** loose aggregates dissociate and recombine repeatedly under cyclic loading and the tight aggregates keep the network integrated and ***,the largest hysteresis of PIP-4A-V with the longest oligopeptide length give the lowest heat generation,which is contrary to the traditional sacrificial ***,the oligopeptide aggregates have repeatable energy dissipation properties and cycle life comparable to or even surpassing those of the linked proteins in NR,resulting in similar tensile strength,fracture toughness,and better fatigue resistance relative to *** deep insight on the role of oligopeptide aggregates is very useful for the engineering rubbers served in dynamic environments.

关键词： polyisoprene Hydrogen bonding Oligopeptides Fatigueresistance

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The Effect of Branching Structure on the Properties of Entangled or Non-covalently Crosslinked polyisoprene

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Chinese Journal of Polymer Science 2021年第1期39卷 113-121,I0008页

作者： Mo-Kun Chen Rong Zhang Mao-Zhu Tang Guang-Su Huang Yun-Xiang Xu College of Polymer Science&Engineering State Key Laboratory of Polymer Materials EngineeringSichuan UniversityChengdu 610065China

The branching structures in natural rubber(NR) were believed to be critical for its superior mechanical properties. However, it is challenging to unravel the branching structure-function relationship of NR due to the complexity of the system. Herein, polyisoprene-(polyisoprene-g-polylactide)(PI-PLA) as model compound containing branching structure was designed and synthesized, which can improve the modulus, strength and viscoelasticity activation energy compared to those of the pristine polyisoprene(PI). The reason is that the branching structure contributes to the entanglement between polyisoprene chains. In order to probe the effect of branching structure on noncovalently crosslinked system, the polyisoprene block of PI-PLA was epoxidized and mixed with Fe3+ ions to introduce coordination bonds. Compared with the linear counterpart, the branching structure obviously enhanced activation energy of coordinated polyisoprenes, remarkably improving the mechanical properies of elastomer.

关键词： Natural rubber Branching structure Noncovalent interaction polyisoprene

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Laser-induced pattern formation from homogeneous polyisoprene solutions

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Chinese Physics B 2008年第6期17卷 2156-2159页

作者：林殿阳黎明王淑杰吕志伟 Institute of Opto-Electronics Harbin Institute of Technology College of Science Inner Mongolia University of Technology School of Management Harbin Institute of Technology

This paper reports that the pattern formation in homogeneous solutions of polyisoprene in toluene saturated with C60 induced by a continuous-wave visible laser is observed experimentally. The transmitted beam patterns change with the increase of the laser irradiation time. In the initial phase, the patterns with concentric ring-shaped structure are formed. In the end, the patterns become speckle-shaped. The incubation time of the transmitted beam widening is inversely proportional to the laser power density and solution concentration. The pattern formation results from the optical-field-induced refractive index changes in the solutions, but the mechanism of optical-field-induced refractive index changes in the polymer solutions needs to be further studied.

关键词： laser-induced pattern formation polyisoprene

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STRUCTURAL STUDIES ON CRYSTALLINE 3,4—polyisoprene

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Chinese Chemical Letters 1993年第6期4卷 541-542页

作者： Hong Fang ZHANG Zhi GONG Fo Song WANG Polymer Physics laboratory,Changchun Institute of Applied Chemistry,Academia Sinica,Changchun,130022

In the paper,the structures of the crystalline 3,4-polyisoprene(3,4-PI) which was first synthesized in our institute,were investigated by using Wide Angle X-ray Diffraction(WAXD);Small Angle X-ray Scattering(SAXS)and Laue photography in various polymerization conditions and elongate *** was found that reducing reaction velocity was favourable for crystalline *** polymeric structures were dependent mainly on nitrogen electron *** degree of crystallinity and long period were increased with elongate ratio,but crystalline size was *** polymers used in the work belong to inhomogeneous particulate *** particulate radii were between 35-164A.

关键词： SAXS WAXD STRUCTURAL STUDIES ON CRYSTALLINE 3,4 polyisoprene

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Effects of the Catalytic System MoO<sub>2</sub>(acac)<sub>2</sub>-TBHP in polyisoprene Epoxidation Using Experimental Design

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Journal of Materials Science and Chemical Engineering 2020年第3期8卷 39-51页

作者： José R. Gregório Elisa Barbosa-Coutinho Annelise E. Gerbase Márcia Pires Fortes Ferreira Marly A. M. Jacobi Instituto de Química Universidade Federal do Rio Grande do Sul Porto Alegre RS Brazil

The epoxidation of polydienes yields materials with improved properties, which can be tuned by the control of the epoxidation degree. In this work, we retake a known process, the epoxidation of polyisoprene, by a different approach, in which the quantification of parameters influencing the epoxidation, such as temperature, oxidant and catalyst concentration, and reaction time degree is evaluated. We measured the influence of each parameter, allowing anyone who aims a polymer with a certain degree of epoxidation to choose which conditions are best suitable for reaching his goal.

关键词： Epoxidation Molybdenum polyisoprene Experimental Design

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POSS-NEODYMIUM COMPLEX{[(i-C_4H_9)_7(Si_7O_(12))Nd]_4NaCl}AS PRECURSOR FOR POLYMERIZATION OF ISOPRENE

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Chinese Journal of Polymer Science 2009年第4期27卷 597-600页

作者：孙维林 Key Laboratory of Macromolecule Synthesis and Functionalization Ministry of Education Department of Polymer Science and Engineering Zhejiang University

The tetrameric neodymium-silsesquioxane cage complex,{[(i-C_4H_9)_7(Si_7O_(12))Nd])4NaCl},was prepared and used as precursor for the polymerization of *** activated by AlEt_3 in the presence of TMSCl,this POSS-Nd complex (POSS=polyhedral oligomeric silsesquioxane) shows a moderate activity for the polymerization,and the effects of different ratios of Al/Nd,Cl/Nd and time on the polymerization were ***,The POSS-Nd complex may serve as models for the silica-supported rare earth cat...

关键词： Incompletely condensed silsesquioxanes Metal silsesquioxanes polyisoprene

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The rapid determination of volatile fatty acid number in para rubber latex using fourier transform-near infrared spectroscopy based on quantification and discrimination model

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Journal of Innovative Optical Health Sciences 2015年第5期8卷 107-115页

作者： Sureeporn Narongwongwattana Ronnarit Rittiron Chin Hock Lim Department of Food Engineering Faculty of Engineering at Kamphaengsaen Kasetsart University NakhonpathomThailand Thai Rubber Latex Corporation(Thailand)Public Company Limited ChonburiThailand

Volatile Fatty Acid number(VFA no.)is one of the parameters indicating the state of quality of Para rubber latex at that particular *** factories analyze this parameter using standard analytical method as in ISO 506:1992(E).Nevertheless,this procedure is complicated,chemical and time consuming,as well as skilled analyst ***,near infrared(NIR)spectroscopy which is rapid,accurate and nonchemicals method was applied to determine the VFA *** latex and concentrated latex based on quantification and discriminant *** best calibration equation was obtained from standard normal variate(SNV)spectra in the region of 6109.7–5770.3,4613.1–4242.9 cm^(-1) with R?0:832,SECV?0:036 and no *** the performance check,statistically it was found that SECV and bias were low enough for practical acceptance and the predicted VFA *** not di®erent significantly from actual VFA *** 95% confidence *** addition,discriminant model was developed to separate good quality latex from the deteriorated latex using VFA *** 0.06 as standard as in ISO 2004:2010(E).The discriminant model can be used to screen the latex with overall accuracy of 91.86%in validation set.

关键词： Hevea brasiliensis latex quality polyisoprene ISO 12099:2010(E)

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Synthetic rubbers prepared by lanthanide coordination catalysts

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Science China Chemistry 2009年第10期52卷 1520-1543页

作者： WenQi Chen FoSong Wang Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun 130022 China

China is rich in rare earth resources. Rare earth elements, also named lanthanides, are number 58 to number 81 elements in the elemental periodic table. They have unique electronic structures and may form various coordination compounds. In the early 1960s, researchers at the Changchun Institute of Applied Chemistry, Chinese Academy of Sciences (CIAC) found the catalytic activities of lanthanide compounds in stereospecific polymerization of conjugated dienes, and published the first paper on this topic in 1964. On the basis of this finding, CIAC launched extensive research activities on lanthanide compounds as diene polymerization catalysts, from a series of fundamental research to the efforts of industrializing the rare earth catalyzed cis-1,4-polybutatine rubber and cis-1,4-polyisoprene rubber. This review aims to summarize the progress in this field in the past half century.

关键词： synthetic rubber polybutadiene polyisoprene rare earth lanthanide coordination catalysts stereospecific polymerization

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Highly stereospecific polymerization of isoprene with homogeneous binary Ziegler-Natta catalysts based on NCN-pincer neodymium precursor

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Science China Chemistry 2010年第8期53卷 1641-1645页

作者： LIU DongTao1,2,CUI DongMei1 & GAO Wei3 1State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied Chemistry,Chinese Academy of Sciences,Changchun 130022,China 2Graduate University of Chinese Academy of Sciences,Beijing 100039,China 3School of Chemistry,Jilin University,Changchun 130012,China State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun China Graduate University of Chinese Academy of Sciences Beijing China School of Chemistry Jilin University Changchun China

The aryldiimine NCN-pincer stabilized neodymium dichloride combined with aluminum alkyls established a new type of homogeneous binary neutral Ziegler-Natta catalyst *** system exhibited high activity and high cis-1,4 selectivity for the polymerization of isoprene (Tp=20 °C,98.2%;Tp=-20 °C,> 99%).Such catalytic performances remained under a broad range of polymerization temperatures and monomer-to-neodymium ratios (from 500 to 8000),reaching high number-average molecular weight (Mn=1582 kg/mol) and relatively narrow molecular weight distribution (PDI=1.68),which was,however,influenced by the amount and bulkiness of aluminum *** investigation of the polymerization was performed,which showed the number-average molecular weight of the resultant polyisoprene had an almost linear correlation with the conversion,suggesting,in some degree,the polymerization with this catalytic system was controllable.

关键词： neodymium cis-1 4 selectivity NCN-pincer complex polyisoprene

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SYNTHESIS OF TRIBLOCK COPOLYMERS OF STYRENE AND ISOPRENE BY A NITROXIDE-MEDIATED LIVING FREE RADICAL POLYMERIZATION

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Chinese Journal of Polymer Science 2004年第1期22卷 55-61页

作者： P. Najafi Mogaddam A. Entezami Lab. of Polymer Chemistry Faculty of Chemistry Tabriz University Tabriz-IranLab. of Polymer Chemistry Faculty of Chemistry Tabriz University Tabriz-Iran

The controlled free radical polymerization of styrene and isoprene initiated with benzoyl peroxide (BPO) in the presence of 2,2,6,6-tetramethyl piperidine-N-oxyl (TEMPO) at 125 'C were performed. The obtained polyisoprene and polystyrene homopolymers served as macroinitiators for block copolymerization of isoprene and styrene to synthesize poly- (styrene-b-isoprene) and poly(isoprene-b-styrene) diblock copolymers. Diblock copolymers with well-defined structures as well as controlled and narrow molecular weight distribution were obtained from the lower-mass polystyrene and polyisoprene homopolymers. These copolymers were found to be active as macroinitiators in the synthesis of the poly(styrene-b-isoprene-b-styrene) and poly(isoprene-b-styrene-b-isoprene) triblock copolymers. 1H-NMR spectroscopy and gel permeation chromatography (GPC) were used for the investigation of polymer structure, molecular weight and polydispersity (PD).

关键词： Diblock and triblock copolymer Controlled radical polymerization TEMPO Polystyrene polyisoprene

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