检索结果-南通市图书馆

Linear Viscoelastic Behaviors of polybutene-1 Melts with Various Structure Parameters

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2016年第2期34卷 174-184页

作者： Hua-feng Shao Shu-lei Wang Xia Dong 贺爱华 Shandong Provincial Key Laboratory of Olefin Catalysis and Polymerization Key Laboratory of Rubber-Plastics(Ministry of Education)Qingdao University of Science and TechnologyQingdao 266042China Beijing National Laboratory for Molecular Sciences CAS Key Laboratory of Engineering PlasticsInstitute of ChemistryChinese Academy of SciencesBeijing 100190China

The effects of weight-average molecular （Mw）, molecular weight distribution （MWD）, and isotacticity on the linear viscoelastic behavior of polybutene-1 melts are studied. It is observed that the linear viscoelastic region becomes slightly narrower with increasing frequency. In frequency sweeps, the transition of the polymer melts flow from Newtonian flow to power-law flow can be observed. The melts with higher Mw and：or broader MWD, as well as higher isotacficity exhibit higher complex viscosity, zero shear viscosity, viscoelasticity moduli, relaxation modulus, broader transition zone, while lower critical shear rate, non-Newtonian index, and the frequency at which elasticity begins to play an important role. The relationship of zero shear viscosity on Mw has been established, which agrees with the classical power law. Furthermore, it is found that the cross-over frequency decreases with increasing Mw and the cross-over modulus increases with narrowing MWD.

关键词： polybutene-1 Molecular weight Molecular weight distribution Isotacticity Linear viscoelastic behaviors.

Polymorphic Transition of Pre-oriented polybutene-1 under Tensile Deformation:In Situ FTIR Study

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2020年第8期38卷 888-897,I0008页

作者： Zhen Zhang Xin Chen Chuang Zhang Chun-Tai Liu Zhen Wang Yan-Ping Liu National Engineering Research Center for Advanced Polymer Processing Technology Key Laboratory of Materials Processing and Mold(Zhengzhou University)Ministry of EducationZhengzhou UniversityZhengzhou 450002China National Center for International Research of Micro-nano Molding Technology&Key Laboratory for Micro Molding Technology of Henan Province Zhengzhou UniversityZhengzhou 450002China

Deformation-induced phase transition of FormⅡto FormⅠin polybutene-1(PB-1)has been investigated by time-resolved Fourier transform infrared(FTIR)spectroscopy over a wide temperature range from 25℃to 105℃.The initial film sample containing orientated lamellae is prepared by pre-stretching of PB-1 melt followed by solidification.This is to realize a homogeneity of subsequent deformation at the mesoscale of lamellar stacks by avoiding large-scale spherulites.The deformation induced phase transition is recognized to occur with two stages:first,FormⅡundergoes the lamellar fragmentation,slipping or local melting after yielding to activate its transition to FormⅠ,which may be realized by releasing the restrictions on chains translational movements in crystalline phase;second,the phase transition proceeds with a continuous dissipation of external work and determines the tensile mechanical response of film.To quantify the relationship between crystalline transition of FormⅡto FormⅠand external tensile field,a simple kinetic equation is well established based on FTIR measurement.The equation can describe not only the dependence of crystal transitional degree on applied specific work,but also the retardation effect of elevating temperature on phase transition.

关键词： polybutene-1 Tensile deformation FTIR Crystalline transition External work

Ultrafast Form Ⅱ to Ⅰ Transition of Isotactic polybutene-1

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2019年第7期37卷 633-636页

作者： Xing Qiu Umair Azhar Jing-Qing Li Ding-Hai Huang Shi-Chun Jiang School of Materials Science and Engineering Tianjin University

Isotactic polybutene-1 (iPB-1) is a semi-crystalline polymer with polymorph and puzzled structural transitions. The stable form I of iPB-1 with excellent physical and mechanical properties can hardly be obtained directly from the melt;instead, metastable form II will spontaneously and slowly transform into form I. Bypassing the unstable form II formation is of great significance in polymer processing, which inspires extensive research on seeking the pathways to direct formation of form I. Methods for accelerating form II to I transition are another main focus in terms of practical approach for directly obtaining form I. Taking advantage of the solvent, an ultrafast transition of iPB-1 from form II to I within minutes has been achieved at room temperature. Such an ultrafast transition is detected after treating with dichloromethane (DCM) at 30 ℃, though the framework of isothermally crystalized iPB-1 spherulite morphology could not be fully modified. The ultrafast II-I transition of iPB-1 is attributed to the solvent-induced packed-mesophase and temperature-selected chain conformation adjustment.This ultrafast transition would shed light on understanding the mechanisms of polymorphic transitions in iPB-1.

关键词： polybutene-1 Ultrafast transition Mesophase Conformation

Structure and Properties of Isotactic Polypropylene/polybutene-1 In-reactor Alloys

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2020年第12期38卷 1382-1391页

作者： Ya-Ping Ma Ning Zhang Wei-Ping Zheng Ai-Hua He Chen-Guang Liu Shandong Provincial Key Laboratory of Olefin Catalysis and Polymerization Key Laboratory of Rubber Plastis(Ministry of Education)School of Polymer Science and EngineeringQingdao University ofScience and Technology Qingdao 266042China

The composition and structure of polymer largely determine the properties of its final products.As a novel polymer material,the composition,structure,and properties of the isotactic polypropylene/polybutene-1 in-reactor alloy(PPIPB alloy)synthesized by sequential two-stage polymerization with Ziegler-Natta catalyst were correlated for the first time in this work.The iPP/PB alloy was fractionated by temperature rising elution fractionation(TREF)in a broad temperature ranged from-30℃ to 140℃,and the chain microstructures and sequence distributions of isolated fractions were analyzed by DSC,GPC,13C-NMR,and FTIR.The iPP/IPB alloy was composed of five components,namely high isotactic PB(PB,85.8 wt96),medium isotactic PB(mPB,5.1 wt%),polyl(butene-1)-block propylene copolymers(PB-6 PP,4.1 wt%6)which contained PB and PP blocks with dfferent lengths according to the isolation temperature,isotactic PP(iPP,2.7 wt%6),and atactic PB(aPB,2.3 wt96).Compared to other commercial pipe materials,the P/iPB alloy presented outstanding thermal creep resistance and gas permeability resistance,high strength and low deformation at high temperature,and appropriate flexural strength.The roles of PP and PB-b-PP components in the alloy were interpreted.This work is expected to elucidate the potential application of PPIPB aloy as pipe materials and provide solutions for the design and synthesis of high performance pipe materials.

关键词： polybutene-1 Aloy Block copolymer Structure Property

Differential Polymorphic Transformation Behavior of polybutene-1 with Multiple Isotactic Sequences

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2020年第2期38卷 164-173,I0007页

作者： Ya-Ping Ma Wei-Ping Zheng Chen-Guang Liu Hua-Feng Shao Hua-Rong Nie Ai-Hua He Shandong Provincial Key Laboratory of Olefin Catalysis and Polymerization Key Laboratory of Rubber-Plastics (Ministry of Education) Qingdao University of Science and Technology

For the solid-solid transformation from form Ⅱ to form Ⅰ of isotactic polybutene-1(iPB),the temperature dependence of form Ⅰ nucleation and growth was deemed to control the transformation process.However,the relationship between formⅠ formation and form Ⅱ disappearance in the transformation process is not clear.In this work,the spontaneous crystal transformation from form Ⅱ to Ⅰ of iPB with 81 mol%mmmm sequence concentration is studied firstly by tracking the two processes,the decay of form Ⅱ and the yielding of form Ⅰ in a wide range of temperature spanning from 0℃ to 50℃ and in a long transformation time ranging from 5 min to 65 days with in situ FTIR and WAXD.Unlike the literature reports,the decay rate of form Ⅱ is firstly found to be lower than the yielding rate of form Ⅰ at all studied temperatures,especially at low transition temperature.This is attributed to the amorphous chains which locate near crystal lamella participating into the nucleation of form Ⅱ.The regular chain folding and growth of i PB form Ⅰ from amorphous chains containing short isotactic sequences also lead to an increase in crystallinity of form Ⅰ compared with that of initial form Ⅱ crystallized at 60℃.An increase in the annealing temperature results in decrease in crystallinity and increase in lamellae thickness of i PB formⅠ.

关键词： polybutene-1 Polymorphic transformation Isotactic sequence Crystallinity Lamellae thickness

The effect of polymerization conditions on crystalline of polybutene-1 catalyzed by metallocene catalyst

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2007年第2期18卷 217-220页

作者： Qi Gu Huang[a]&Email:qgh96@*** Ya Ping Sheng[a] Kun Xue Deng[a] Li Fu Ma[a] Yi Xian Wu[a] Wan Tai Yang[a] [a]State Key Laboratory of Chemical Resource Engineering College of Material Science and Technology Beijing University of Chemical Technology Beijing 100029 China

polybutene-1 was synthesized stereoselectively with the precursor η(5)-(pentamethyl-cyclopentadienyl) tribenzyloxide titanium (Cp*Ti(OBz)3) and methylaluminoxane (MAO). The effects of polymerization conditions, trimethyl alumina (TMA) content in MAO and temperature on the crystalline and molecular weight of the products, and catalytic activity were investigated. The structural properties of the polybutene-1 were characterized with (13)C NMR and WAXD.

关键词： Metallocene catalyst Methylaluminoxane polybutene-1 Structure

Crystallization and Phase Transition of 1-Butene Copolymers with Distinct Cyclic Co-Units

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemistry 2022年第12期40卷 1429-1436,I0002页

作者： Long Liu Yahui Lou Chunjing Qv Zhe Ma Yuesheng Li Tianjin Key Laboratory of Composite and Functional Materials and School of Materials Science and EngineeringTianjin UniversityTianjin 300072China

The dimethylpyridylamidohafnium catalyst was used to synthesize 1-butene/cyclohexene and 1-butene/vinylcyclohexane random copolymers,which have extra six-membered cyclic co-units in main chain and side chain,respectively.For the obtained copolymers of different incorporations,the crystallization from amorphous melt and the solid phase transition from tetragonal to trigonal phases were investigated with differential scanning calorimetry.Both of the incorporated cyclic co-units decrease the crystallization kinetics,but the presence of cyclohexene keeps the melting temperature of copolymers constant.Interestingly,the strong memory effect of crystallization can appear at the elevated temperature even above the equilibrium melting temperature,as the content of co-units was increased.The 1-butene/vinylcyclohexane copolymer with 1.52 mol%co-units exhibits a rather strong memory effect with the broad Domain Ila width of 43℃and the crystallization temperature raising of 24℃.Furthermore,the transition of tetragonal phase into trigonal phase was also explored for different co-units and incorporations.It was found that both of the cyclohexene co-units and vinylcyclohexane co-units effectively slow down the kinetics of phase transition.However,the vinylcyclohexane co-units have a much higher efficiency in suppressing phase transition than the cyclohexene co-units,where 0.53 mol%vinylcyclohexane can com-pletely stop phase transition within 1320 h.Considering the fact that copolymers with vinylcyclohexane co-units actually have lower glass transition temperatures,it was indicated that the suppression of phase transition is also largely influenced by the steric co-units in the side chain for the helical and positional adjustments,not only by the segmental mobility.

关键词： polybutene-1 Cyclic co-units Kinetics Memory effect Phase transition

Mechanism of Polymorph Selection during Crystallization of Random Butene-1/Ethylene Copolymer

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2016年第8期34卷 1014-1020页

作者： Yao-tao Wang Pei-ru Liu Ying Lu 门永锋 State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied Chemistry Chinese Academy of Sciences University of Chinese Academy of Sciences

Starting from an initial sample of butene-1/ethylene copolymer with stable form I＇, we examined the nucleation of different crystalline polymorphs （here metastable form II and stable form I＇） at different isothermal crystallization temperatures after being melted at different melt temperature （Tmelt）. When Tmelt was just above the melting temperature （Tm） of the crystallites, self-seeding took place. There, residue crystallites served as nuclei leading to the crystallization of the same crystalline phase. When Tmelt was a few degrees above the Tin, self-seeding was disabled due to complete melting of the initial crystals. Upon crystallization, the selection of the different polymorphs in this random copolymer was found to depend on an interplay between the domain size of segregated long crystallizable sequences and the size and energy barrier of the critical nucleus of the respective crystalline forms. Our results provide a clear understanding of the polymorphs selection during crystallization of a random copolymer as well as homo-polymers under confinement.

关键词： Crystallization Random copolymer polybutene-1 Polymorphism.