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DIELECTRIC PROPERTIES OF 1, 2-POLYBUTADIENES

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Chinese Journal of Polymer Science 1987年第2期5卷 120-124页

作者：倪少儒余赋生沈联芳钱保功 changchun institute of applied chemistry academia sinica changchun changchun institute of applied chemistry academia sinica changchun

The dielectric permittivity and loss tangent of 1,2-polybutadienes with different chain structures were determined as a function of temperature from-180℃ to 100℃ at different frequencies, and the frequency and structure dependence of the dielectric propertie of 1,2-polybutadienes have been investigated. It is found that a maximum of the permittivity occurs in the glass-transition region. The width of the glasstransition peak increases with increasing frequency while its height has little change. With a rise in the content of 1,2-units, the permittivity decreases and the height of the glass-transition peak slightly grows. A maximum of the width of the glass-transition peak appears when the content of 1,2-units is about 45%. Both the permittivity and dielectric loss drop down as the growth of the content of syndiotactic 1,2-units.

关键词： 1, 2-polybutadiene Dielectric properties Permittivity Loss tangent

THE RADIATION CROSSLINKING OF EPR/SBR BLEND

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Chinese Journal of Polymer Science 1990年第3期8卷 279-282页

作者：张万喜吕英涛孙家珍 changchun institute of applied chemistry Academia Sinica Changchun

The radiation crosslinking of EPR/SBR blend has been studied. A relationship between sol fraction and radiation dose for the different weight ratio polymer blends and the method to calculate βb value of EPR/SBR blend... 详细信息

关键词： Radiation crosslinking Blend Glass transition temperature SBR EPR.

CHARACTERIZATION OF BRANCHING POINT DISTRIBUTION IN THE SOL OF IRRADIATED POLYSTYRENE WITH SEC-LALLS

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Chinese Journal of Polymer Science 1991年第2期9卷 177-179页

作者：张万喜王谋智孙家珍 changchun institute of applied chemistry academia sinica Changchun

In this paper, the change behavior of branching point distribution of irradiated polystyrene in sol has been first studied by the SEC-LALLS method. The experimental results show that branching parameter of the part with lower molecular weight in the sol changes little at the early stage of irradiation and that of the part with the higher molecular weight becomes greater with the increase in radiation dose.

关键词： Irradiation of polystyrene Branching point distribution of the sol Branching parameter, SEC-LALLS.

STUDY ON THE EPOXY RESIN TOUGHENED BY HYDROXY-TERMINATED BUTADIENE-ACRYLONITRILE COPOLYMER

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Chinese Journal of Polymer Science 1990年第4期8卷 335-341页

作者：韩孝族李绍英张庆余 changchun institute of applied chemistry Academia Sinica

Toughened epoxy resin with excellent properties was obtained by adding organic acid anhydride curing agent and hydroxy-terminated butadiene-acrylonitrile copolymer (HTBN), which is cheaper than CTBN. The anhydride reacts with both epoxy groups on epoxy resin and hydroxyl groups on HTBN. As a result the soft long chains of HTBN and the rigid chain of epoxy resin form one network, giving the resin toughness. Two-phase structure of the toughened resin was observed by SEM and TEM.

关键词： Epoxy resin Modification of epoxy resin HTBN Morphology

CHARACTERIZATION OF γ-IRRADIATED CRYSTALLINE POLYMERS Ⅱ ISOTHERMAL CRYSTALLIZATION KINETICS OF γ-RADIATION INDUCED CROSSLINKED POLYAMIDE 1010

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Chinese Journal of Polymer Science 1989年第1期7卷 54-65页

作者：冯金华张利华陈东霖 changchun institute of applied chemistry Academia Sinica

Polyamide 1010 is a γ-radiation crosslinkable polymer. After irradiation, it is possible to raise its service temperature up to 240℃ . Network formation greatly changes the crystallization behaviour of the polymer. In the present work, DSC was used to examine its isothermal crystallization kinetics. It is found that in addition to the necessity of more undercooling and the lowering of crystallization rate, the primary crystallization stage of the irradiated polymer is shortened. This effect is more evident with increasing radiation dose and content of enhanced difunctionai erosslinking agent. However, the crystallization mechanism of the primary stage is not changed as evidenced by the constancy of Avrami exponent. The lamella end surface free energy σ_e calculated according to Hoffman's equation is very sensitive to γ-radiation. It increases abruptly in 2—3 fold even though the radiation dose is not high enough. The origin of this phenomenon may be accounted for in terms of network structure of the polymer.

关键词： γ-Irradiation Crosslinking Polyamide 1010 Isothermal crystallization

MORPHOLOGY OF POLYBUTADIENE “SHISH KEBABS”

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Chinese Journal of Polymer Science 1989年第1期7卷 1-8页

作者：徐洋周恩乐余赋生钱保功 changchun institute of applied chemistry Academia Sinica

Shish kebab structure of cis-1 , 4-polybutadiene has been obtained by quiescent solution crystallization at suitable temperature. The morphology and growth mechanism of formation of shish kebab structure have been stu... 详细信息

关键词： Morphology of polymers Polybutadiene Shish kebab Solution crystallization

STUDY ON CASTOR OIL POLYURETHANE/POLY (METHYL METHACRYLATE) AB CROSSLINKED POLYMERS

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Chinese Journal of Polymer Science 1991年第1期9卷 31-38页

作者：杜郢韩孝族刘文忠 changchun institute of applied chemistry Academia Sinica

Castor oil polyurethane/poly(methyl methacrylate) AB crosslinked polymers (ABCP) were synthesized by free radical copolymerization of MMA and vinyl-terminated castor oil polyurethane which was obtained from isocyanate-terminated castor oil polyurethane and hydroxyethyl methacrylate The mechanical properties, transition and relaxation, as well as compatibility and morphology of the ABCP were investigated by changing the component. The results show that the ABCP is a semicompatible system and the compatibility of the two components decreases with increasing content of the hard segment. The mechanical and damping properties of the ABCP are obviously superior to that of their homopolymers. The damping value is mainly controlled by cross[ink density of the ABCP but the T-g value by component.

关键词： AB crosslinked polymers Castor oil polyurethane PMMA Dynamic mechanical properties Dielectrical relaxation spectrum TEM.

Studies of Electrochemical Catalytic Reduction Reactions of Tetraphenylporphinatocobalt/1,2-Dibromoethane and 1,2-Dichloroethane Systems in Nonaqueous Media

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Science China chemistry 1994年第3期37卷 257-264页

作者：林祥钦刘殿骏汪尔康 changchun institute of applied chemistry Academia Sinica Changchun 130022 PRC

Electrochemical catalytic reactions of tetraphenylporphmatocobalt were studied in DMF and EtCl2 solutions in the presence of 1,2 dibroraoethane and 1,2-dichloroethane utilizing cyclic voltamme-try, thin-layer electrochemistry, in situ UV-visible spectroelectrochemistry and computer digital simulation methods. Homogeneous rate constants for reactions of electrogenerated Co(Ⅰ)TPP species with 1,2-dibro-moethane and 1,2-dichloroethane were determined as 1. 2×103 and 5 mol-1 · dm3 × s-1, respectively. Neither alkylation nor degradation of CoTPP was observed.

关键词： cobalt porphyrin catalytic reduction dichloride ethane electrochemistry spectroelec-trochemistry.

STUDY ON FACTORS AFFECTING ROOM TEMPERATURE TRANSITION OF POLYTETRAFLUOROETHYLENE

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高分子科学(英文版) 1986年第2期4卷 170-179页

作者：傅铁垣莫志深韩平綦玉臣吴淑云陈东霖 changchun institute of applied chemistry academia sinica changchun changchun

In the X-ray diffiaction intensity distribution diagram of PTFE, three diffraction peaks exist inthe range of Bragg angle 30--45°, which are very sensitive to the Crystal trausition at room *** 15℃, the crystal is triclinic and the 'small spikes' along with the main peaks appear on the dif-fraction scans due to the distortion of the unit cell, while at 23℃, distortion no longer exists, 'smallspikes' disappear completely. When the temperature is raised to 34℃, the hexagonal crystal fur-ther randomizes and the peak at Bragg angle 42°vanishes. We assigned correctly Miller index (108) tothis peak and used 2θ=30--45°region ('sensitive region') as a criterion to characterize qualita-tively the crystal transition. It has been found that some factors such as γ-irradiation, cold press-ing, drawing, calendering and copolymerization which are usually encountered in the fabrication orapplication of PTFE articles have profound effect on the crystal transition as evidenced by X-raydiffraction patterns and DSC thermograms. The information obtained in the present work isbeneficial to the use of PTFE articles.

关键词： hexagonal disappear fabrication irradiation Bragg characterize correctly longer triclinic drawing