最新刊期
卷 ， 期 3 ， 1994
- 摘要：LiLn (π - C3H5)4·nD (Ln=La,Tb,n=3;Ln=Ce,Pr,ND,Sm, Gd, Er, n = 2;Ln=Y,Dy,n= 2. 5; D=dioxane) can polymerize isoprene and styrene except Erium complexes, in which Yittrium complex is with the highest activity.About 43 -81% cis- 1.4 chains are contained in the polyisoprene with different complexes. The insertion reaction of isoprene between π-allyl and rare earth in the previoius paper was confiremed.High 3,4-polyisoprene was obtained by adding some Lewis bases to the polymerization systems.Polystyrene was identified as atactic polymer by IR spectrum.
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发布时间：2021-03-19 - 摘要：tereospecific polymerization of styrene was conducted in toluene using theMgCl_2/TiCl_4, NdCl_3/AlEt_3 catalyst. With increasing monomer concentration , the molecular weight of the products are increase while the polymer yield, the catalytic efficiency , and the isotacticity of the products are all first increased,reaching a maximun , and then decreased gradually. A maximum isotacticity of 98% of the products has been obtained. Results of DSC determinations show that an adequate content of atactic polystyrene(aPS) is favourable of the crystallization of isotactic polystyrene(iPS),but the addition of more aPS linearly decreases the crystallinity of iPS because of the dilution effect. The content of polyethylene(PE) in blends of iPS/PE has no significant influence on the crystallinity of iPS while polycarbonate (PC)excerts a more complicate effect on the crystallinity of iPS in iPS/PC blends.
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发布时间：2021-03-19 - 摘要：he polystyrene supported polyethylene glycol resin was prepared by grafting the polyethylene glycol onto the chloromethylated copolymer of styrene and divinylbenzene in the presence of sodium or concentrated sodium hydroxide solution.The factors which affectal the grafting reactions were investigated. The proceeding of the grafting reaction was followed by electron microscope photogram and IR spectral analysis.
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发布时间：2021-03-19 - 摘要：he corresponding polymerization kinetic equation is introduced into Gel-Sol Distribution equation for Aa-Bb condensation polymerizatio in this paper. We simulate the total condensation polymerization process, calculate the time evolution of reaction degree , sol fraction and network crosslink density. We solve the mathematical simulation of polymer network for nonlinear condensation polymerization. The mathematical simulated curves of sol fraction against reaction degree are in agreement with experimental data.
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发布时间：2021-03-19 - 摘要：tyrene-ethylene copolymers were synthesized by copolymerization of styrene and ethylene using the MgCl2/TiCl4, NdCl3/AlEt3 catalyst and characterized by 13C-NMR, IR, DMA and solvent extinction fractionation . The results show that the catalyst exhibits high activity for the copolymerization of styrene and ethylene and the obtained copolymers are composed of various comonomer sequences . The mechanical properties of blends consisted of polystyrene and the copolymers are much better than those of polystyrene.
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发布时间：2021-03-19 - 摘要：Phenophthalein polyether-ether-sulfone (PES -C ) and polyether-etherketone (PEK-C) were mixed mechanically and their melt viscosihes were measured with a cone-plate viscometer. A significant negative derivation was shown in comparison to "log-addihvity rule" for the viscosity of the blends. It is demonstrated that the melt flow and the stability are suitable for injection molding of these materials.
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发布时间：2021-03-19 - 摘要：The effects of untreated kaolin and Gamma-glycidoxypropyltrimethoxysilane (KH560) -treated kaolin on isothermal and nonisothermal nystallization of nylon6 (PA6) have been studied by means of Differential Scanning Calorimetry. The results show that both the untreated kaolin and the KH560-treated kaolin play the role of nucleating agent. Compared with the untreated kaolin, the KH560-treated kaolin improves more effectively the crystallization rate of PA6. This is attributed, in part, to the increase of nucleation density caused by the finer dispersion of the KH560-treated daolin than the untreated kaolin in PA6 matrix and,partly,to the increase of the crystallization growth rate caused by the improvement of the compatibility between PA6 and the KH560-treated kaolin.
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发布时间：2021-03-19 - 摘要：The lacquer polysaccharide (LPS)was isolation from Sap of lacquer tree (Rhus Vernicifera), and purified by 732 cation -exchange resin and Sephadex G-100 column Chromatography. Its monosaccharide components were identified by paper and gas chromatography as following: D-galactose, D-glucuronic acid, L-Aiabinose and L- Rhamnose (7.7:1.8: 0.4:0. 1 by mol). The molecular wieght (Mw) was obtained to be 1.25 × 105 by HPGPC. The LPS was subjected to reduction of carboxyl groups, mathylation, periodate okidation and Smith degradation,and then was analyzed by GC-MS,IR,1H-NMR,13C-NMR. The results showed that LPS consists of a β(1→3) D-galactose main chain with a number of side chains, which consist of glucuronic acid Arabinose and Rhamnose. The side chains place on some of the galactose residues at C6 position with content ratio of β(1→3) to β(1→6) (1.83:1).
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发布时间：2021-03-19 - 摘要：n this work three kinds of polyethylene terephthalate /polyamide 66 (PET/PA66) blends are prepared by means of different ways, i.e., by mixing of solution, melt Ⅰ (simply mechanical) and melt Ⅱ(including ester-amide exchange reaction), respectively . The morphology and rheological properties of these blends are inveshgated. Especially , it is stressed that the influence of the ester-amide exchange reaction under the catalysis of terephthalic acid to the compatibility of PET and PA66 in blends.
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发布时间：2021-03-19 - 摘要：PN mercapto-amine chelating resins were prepared by the reaction of chloromethylthiirane adsortal in the macroporous crosslinked polystyrene(PSt) bead as the first network with polyethylene polyamines to form acrosslinked polymers as the second network. The pore structure of the IPN chelating resins were measured. The resins show much less expanding extent in acid media and better adsorption properties for Ag+ and Au3+ than the corresponding gel chelating resins . The adsorption capacities for Ag+ and Au3+ are as high as 432mg Ag+/g and 553mg Au3+/g,respectively. The adsorption efficiencies for Au3+ are more than 99%.
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发布时间：2021-03-19 - 摘要：A process for ethylene dimerization to butene-1 and copolymerization of the in situ-formed olefin with ethylene using the dual catalyst systems, which consist of a dimerization catalyst Ti (OBu)4 and a copolymerization catalyst TiCl4/MgCl2, has been developed . Such catalytic Systems allowed the synthesis of the linear low density polyethylene(LLDPE) from a single monomer source. The kinetic behaviours of ethylene dimerization were studied .Variations in the molar ratio of two catalysts and the pre-run time of the dimerization provide flexibility for changing the de-gree of beanching of polyethylene and,as a consequence,its physical properties such as crystallinity,density and melting point. The results show that the dual catalyat system used could easily produce LLDPE (D=0.91-0.93)with levels of 10-40 branches per 1000carbon atoms.
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发布时间：2021-03-19 - 摘要：he viscosity and flow behavior of the concentrated solutions in the formic acid aqueous solution have been studied by using RPX -705 Rheopexy Analyzer under various concentration (1--5g. 100ml ), temperature (25 -45℃ ), pH of solvent (0.63 -2. 16 ) and ionic strength (0. 04 -0.4mol·1-1 NaCl salt). It was discussed that the flow index n and flow activation energy E_r change with polymer concentration and temperature .It has been observed that zero shear viscosity de creases with increasing ionic strength and decreasing pH of solvent.
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发布时间：2021-03-19 - 摘要：The permeability coefficients of five different 2, 2 - bis (3, 4 -dicarboxyphenyl) hexafluoropropane dianhydride (6FDA)-based polyimide membranes to H2, CO2, O2, N2 and CH4 have been measured at 0. 6MPa and at the temperatures from ambient up to 100 ℃. The temperature and pressure dependency of permeability coefficients of 6FDA-based polyimides is smaller than other standard glassy polymers having more flexible backones. 6FDA-DABP and 6FDA-DMMDA have still higher permeability coefficients at 100℃. The favorable gas separation property, excellent thrmal and mechanical durability,and good processability make 6FDA-DABP and 6FDA-DMMDA to be promis-ing candidate for membrane-based gas separation application.
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发布时间：2021-03-19 - 摘要：A thermotropic liquid crystalline aromatic copolyester containing naphthalene rings (LCP) was blended with polysulfone and extruded. Rheological measurement shows that this LCP decreases blend viscosity to such an extent that the viscosity of blends even lower than that of LCP itself . In blend extrudates, an anisotropic and skin-core structure reinforced by LCP fibrils has been formed by shear flow of extrusion. Copolyester fibrils have been generated in extrudates even at LCP concentrations as low as 2 or 0.5%. LCP fibrils has increased tensile properties if oiktsykfibe, Tebsuke nidykys if extryded strabds cibtaububg 20% LCP is 2.5 times of polysulfone.
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发布时间：2021-03-19 - 摘要：lory's equation-of-state theory with modified combinary rules was applied to estimate the thermodynamic parameters of poly (ethylene oxide ) and poly(vinyl acetate) blending system. For this purpose, heats of mixing , densities, thermal expansion coefficients and thermal pressure coefficients for this system were measured. The heats of mixing of blends in all the range of compositions by application of Hess's law were negative. And the interactionparameters, the exchange enthalpy and the excess volumes were negative too. These results supported strongly from the experimental and the theoretical point of view that this blending system are miscible.
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发布时间：2021-03-19
Research Article
- 摘要：The cyclic initiating system of Ce4+ - Ce3+ - Ce4+, in which the product of reduced ion Ce3+ forming from Ce4+ after initation being oxidized again to the original oxidizing ion Ce4+ is examined. The characters of process of the graft copolymerisation using the cyclic initiating system is compared with the ones using ceric and persulphate individually. When using the cyclic systerm as initator, it was more effective to graft polymerise acylamide onto starch and a rather high proportion of graft copolymer was made as opposed to using persulphate individually.
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发布时间：2021-03-19 - 摘要：ellulose is treated with alkali in several kinds of organic solvent under the same condition, which is followed by carboxymethylation. The analysis of the X-ray diffraction of intermediate of alkalinization shows the nature of solvent and the water content have great effect on the alkalinization andcarboxymethylation of cellulose.
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发布时间：2021-03-19 - 摘要：he mechanical properties of short glass fiber toughened R-PVC were analysed. The mechanisms of the short glass fiber toughened R-PVC, based on the sample broken section were analysed by the SEM. The influences of different toughening agents on the composite properties have been studied. Results showed that the toughening of the short glass fiber were well explained by the proposed model put forwarded in the paper, and the experimental phenomena of different toughening agents on the composite may be illustrated.
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发布时间：2021-03-19 - 摘要：queous solution polymerization of acrylamide (AAm) was demonstrated by using initiation system consisting of N-methacryloyl-N '-pyrimidinopiperazine (MPMP ) and persulfate (KPS). The polymerization rate equation was obtained to beRp = Kp[MPMP]1/2 [KPS]1/2 [AAm]1.0The overall activation energy for the polymerization was calculated by Arrhenius quation to be Ea= 5.6 KJ/mol. The redox nature for the polymerization was clarified. A super high molecular weight up to 107 of PAAm was obtained by using this initiation system. From the fluorescent analysis, it was confirmed that MPMP not only acted as a component of the redox system, but also entered into the acrylamide polymer chains.
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发布时间：2021-03-19 - 摘要：he absorption spectra and the stability of CTC of Fc/BPO in acetonitrile were investigated . The association constant, (K=4lmol-1), and the extinction coefficient , (ε= 240M-1 cm-1 ) of CTC were measured. It was found that the CTC is quite stable under - 20 ℃. But, it can be decomposed rapidly then to initiate polymerization of MMA efficiently by producing radical under room temperature.
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发布时间：2021-03-19 - 摘要：he ethylene-vinyl alcohol copolymer membrane with polyionically complexationalized layer has been prepared by in situ polyionic complexation from cationically modified surface of EVAL membrane and phosphorylated EVAL aqueous solution, which can be considered as a feasible route to modify the surface of membrane for improving the properties , and which is a way to avoid the using of shielding solvent for the processing of polygonic complexes. The condition for the phosphorylation of EVAL has been studied. The effect of the chemical composition of the polyionic complex membrane on the contact angle, water con-tent,mechanical and thermal properties,as well as blood compatibility have been investigated.
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发布时间：2021-03-19
Research Bulletin
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