最新刊期
卷 ， 期 1 ， 1988
- 摘要：The microstructure and sequence distribution of 3,4-polyisoprene obtained with Fe(acac)3-phen-AlEt3 catalyst have been examined by C-13 NMR spectroscopy. The results show that 3,4- cis-1,4 and trans-1,4 contents calculated respectively from aliphatic and olefinic carbons are in agreement on the value and it was found that monomer units of 3,4-polyisoprene exist in a small amount of "head-head" and "tail-tail" structure in addition to "head-tail" linkages.
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发布时间：2021-03-19 - 摘要：Method for determining simultaneously th molecular weight and the Mark-Houwink coefficients for arylene siloxane polymer by using GPC and intrinsic viscosity data were deve-lopped. Porous silica beads column with efficiency of more than 4200-5500 plates per metre, was used. The polydispersity index of polymers were found to be 2. The molecular weight distribution becomes narrower and the molecular weight is lowered after milling.
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发布时间：2021-03-19 - 摘要：The intrinsic viscosities, [η] , of three sodium cellulose sulfate samples, with known molecular weight and Degree of Substitution=1, were determined at 25℃ under different ionicstrengths, I, of NaCl. [η] vs. and logs vs. log [η]0.1 plots are linear. According to Smidsrod's Eq, values empirical parameter B are found to be 0.088. 0.090 and 0.088, respectively. The empirical parameter B, which is a measure of relative stiffness of different polymer chains, can also be used as a measure of the response of [η] to the addition of salt for different polyelectrolytes.
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发布时间：2021-03-19 - 摘要：Copolymerization reaction of a-methyl methacrylate and ethylene glycol dimethacrylate was inverstigated in the presence of toluene and 2-ethylbutanol. The phase separation of the co-polymers was studied by means of trubidity changes in the course of polymerization reaction. The mechanism of the pore formation of copolymers has been explained. The experimental data of pore sizes and surface areas of copolymers are given. Factors affecting the properties of the copolymers are discussed.
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发布时间：2021-03-19 - 摘要：The optical properties and viscocity behaviour of xanthan in the aqueous solution were studied at different concentrations and temperatures by polarized light microscope, Rheotest-2 viscometer and small angle light scattering methods. The aqueous solution of the xanthan shows the characteristics of cholestcric liquid crystal at a concentration of 3%. Formation of cholesteric liquid crystal depends on temperature.
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发布时间：2021-03-19 - 摘要：The effects of temperature on the reactivity ratios are different in various solvents. The complex constants for monomers and solvents have been determined by NMR spectroscopy. The values of enthalpy and entropy for monomers interacting with solvents have been calculated. In accordance with these results, the dependance of monomers reactivity radio on the polymerization temperature has been discussed.
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发布时间：2021-03-19 - 摘要：Vapour pressure osmometry is widely used in the determination of number average molecular weight, Mn, of oligomers and polymers in the lower range of values. We demostrate by means of analysis of the literature data and our own experiment that the calibration constant varies with the molecular weight of the solute. But up to now there has been no theory to describe the dependence. In this paper a new model has been put forward to describe this effect. With the help of the model, we can clearly describe the dependence of the solute on K.
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发布时间：2021-03-19 - 摘要：In this paper linear hydrocarbon copolymers containing certain amount of function groups were used as the support such as styrene-acrylic acid copolymer (SAAC) and styrene-2-(methyl sulfinyl) ethyl methacrylate copolymer (SMC). The preparation of polymer-supported rare earth metal complexes (SAAC·Nd and SMC·LnCls) and their infrared spectra were described.The catalytic system formed from polymer-supported neodymium complexes shows high catalytic activity and stereospecificity for butadiene polymerization. The catalytic efficiency for SMC.NdCl3-Al(i-C4H9)3 system is twice or triple that of NdCl3.4DMSO system. The cata-lytic efficiency of the ternary system,SAAC.Nd-Ph3CCl-Al(i-C4H9)3, reaches up to 170 kg polybutadiene/g. Nd.hr. The cis-1,4 content of polybutadiene is more than 98%. This system was also used for isoprene polymerization. The cis-1,4 content of the polyisoprene obta-ined is about 95%.
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发布时间：2021-03-19 - 摘要：The terminal structures of poly-l,3-pemadiene chains obtained by rare earth catalyst have been investigated with C-13 NMR method and effect of polymerization temperature on micros-tructure of the polymer has been studied. According to the experimental results it was supposed that the terminal active growing chain of the polymer would be anti- and syn-π-allyl formed in the "head-tail" and "tail-head" addition of the monomer. Therefore, there are four configurations of π-allylic terminal in the stereoregular polymerization of 1,3-pentadiene. When the polymerization temperature was reduced,the content of cis-poly-1,3-pentadiene increased. It is explained by the isomerization between the anti- and syn-π-allyl. The process forming trans-1,2 unit in the polymer was described.
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发布时间：2021-03-19 - 摘要：The small-angle X-ray scattering (SAXS) technique was applied for the study of the pore structure of Polymeric adsorbents. This paper relates the principle, experimental, procedure and requirements and the experimental results from dry and wet swollen Leads of polymeric adsorbents. The sample 6×100, which was prepared with 6% of divinylbenzene and 100% of petrol as porogenic agent were investigated with the above mentioned instrument in order to find out their average pore diameters and pore distribution under the swollen con-dition. The relation of the change of average pore diameter as the increase of adsorption of solvent was obtained. The adsorption and swollen mechanism were discussed.
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发布时间：2021-03-19
Research Article
- 摘要：The effects of some factors on the dynamic mechanical properties (DMS) of polystyrene/ poly (n-butyl acrylate) (PS/PBA) latex interpenetrating polymer networks(IPNs) were studied with Rheovibron Viscoelastometer. It was found that the DMS curves under different frequencies can not superpose each other by simple shifting. The glass transition region broadens with the increase of PS content in the latex IPNs, and the influence of crosslinking density on the latex IPNs is not the same as that of sequential IPNs. The possible reasons for these pheno-mena were discussed.
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发布时间：2021-03-19 - 摘要：The microdomain morphology of a series of MDI/BDO/PTMG segmented polyurethane block copolymers has been observed by transmission electron microscope. The microdomain size ranging from several tens to a few hundreds A is in the same order with that measured from SAXS. The degree of the microdomain size dispersion increases with increasing the hard segment content in the copolymers. These observed microdomains can be considered as the basic morphology of the hard segment domains and the variation of their sizes and shapes can be related to the content and length distribution of the hard segments. The microdomains exhibit the tendency to aggregate nad form the macrodomains which are larger in size (usually from several thousands A to a few μm)and usually were mistaken for the basic morphology of the hard-segment domains in previous publications.
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发布时间：2021-03-19 - 摘要：The unliving chains of aliphatic polyester were transformed into dicationically living poly-(THF-b-ester-b-THF) chains. By terminating the living chains with liquid ammonia, the α,ω-diaminotriblock co-oligomer was synthesized. This primary amine telechelic triblock modified the epoxy resin to give a toughened product with high strength which is due to the phase separation as demonstrated by viscoelastic data and scanning electron microscopy.
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发布时间：2021-03-19 - 摘要：Polystyrene-divinylbenzene (4%) copolymer beads were combined with tellurium tetrach-toride in chloroform to form a complex containing 8.86% of chlorine which corresponding to 3.29×10-4mol TeCl4/lg complex beads. The complex can be used to catalyze a lot of organic react ions in higher yield ,such as esterification, acetalization, ketal formation, and ethierifica-tion. The complex catalyst is stable in air at least one year and can be resused a few times.
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发布时间：2021-03-19 - 摘要：The polymerization of methyl methacrylate (MMA) initiated by benzoyl peroxide (BPO), lauroyl peroxide (LPO) coupled with N,N-di(2-hydroxyethyl)-p-toluidine (DHET), and N, N-di(2-hydroxyprojyl)-p-toluidine (DHPT) binary systems was studied and discussed. The effects of organics peroxide and amine on the rate of polymerization, the activation energy of polymerization and the polymerization rate equation were determined respectively.
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发布时间：2021-03-19 - 摘要：2-Phenyl-4-methylene-l,3-dioxolane (PMDO) as an electron donor can spontaneously co-polymerized with maleic anhydride (Manh), methyl methacrylate (MMA) and acrylonitrile (AN) as the electron acceptors. The order of their polymerization activity and alternating-copolymerization tendency are: Manh>AN>MMA, which are the same as decreasing order of e values of the monomers. The formation of CT complexes PMDO-Manh and PMDO-AN was ascertained by UV and NMR spectroscopies. It was also discussed that the different protons of the same electron acceptor in the CT complexes have different chemical shifts.
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发布时间：2021-03-19
Research Bulletin
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