最新刊期
卷 ， 期 6 ， 1988
- 摘要：The determination of number average molecular weight of copolyether and mixed polye-ther has been studied by use of 1H-NMR. It can be calculated by measuring the ratio of 1H-NMR absorptions of the relative protons in the polymeric structure to those of -COOCH2/2 and -COOCH ester-H. Agreement with end hydroxy chemical method was observed.
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发布时间：2021-03-19 - 摘要：The method of variance-range function[1] was used for the analysis of X-ray line proflie of 010 and 100 diffraction of annealed PET fibers．Their average crystallite sizes M and the distortion factors g of second kind lattice diatortion were determined．The plane-spa-cings d of the (010) and (100) crystal planes were also obtained from the peak separation procedures. In M as afunction of l/Ta (Tai annealing temperature) are reported in Fig．2．h is shown that the fitting of each set of data needs two straight lines，crossing each．other at T*= 503 K．The polydispersity indices of crystallite size Mm／M are shown in Fig．3 as a function of n．There is a maximum in each of the Mm／M～Ta curves at T*=503 K． It can be seen from above mentioned observation that densitification and growth of crystalites in PET fibers take place following different molecular mechanism at temperature above or below the T*．The molecular motion of smaller unit can take place belOW the T*．The cooperation motion of larger unit (=3.5—4 smaller units) is allowed just above the T*．
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发布时间：2021-03-19 - 摘要：Ethyl-acetyl cellulose ((E-A)C) could dissolve in organic acid solvent such as trifluoro-acetic acid (TFA), dichloroacetic acid (DCA) and acetic acid (AA) and form lyotropic liquid crystal above the critical concentration C1. With increasing concentration the solutions transformed form isotropic to anisotropic phase through a biphasic range. When the an-isotropic solutions were heated, they changed first to the biphase and then to the isotropic phase. The mesomorphic phase could form again when the solutions varied greatly at the transition between biphasic and anistropic phases. In some conditions there were spherulitic liquid crystals in the anisotropic solutions. The rigidity of the chains of (E-A)C increased with increasing acidity of the organic acid solvent systems. It caused the critical concentration C1 to decrease with increasing the acidity of the solvents.
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发布时间：2021-03-19 - 摘要：The effects of molecular weight and temperature on crystallization processes at low temperature for cis-l,4-polybutadine prepared with rare-earth catalyst (Ln-PB) have been studied by WAXD method. In the range of molecular weight from Mη≈2.13×105 to 46.8×105 there are a maximum of crystallization rate at Mη≈29 × 105 and a minimum at Mη≈8×105. The temperature related to maximum crystallization rate, Tc, max is observed to be between -60℃ and -70℃. The degree of equilibrium crystallinity of Ln-PB is independent of mo-lecular weight at Mn greater than 106,also the linearity is shown between the correspondent remperature,degree of equilibrium crystallinity and molecular weight. Values of unit cell pa-rameters of Ln-PB increase with temperature. The main crystallzation of Ln-PB belongs to heterogeneous nucleation. The crystallization processes are mixed growth one and two di-mensions.
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发布时间：2021-03-19 - 摘要：Two new polysiloxanes with condensed rings have been synthesized via Diels-Alder reaction of polyvinyl siloxane with phencyclone and acecyclone respectively. Using α-chlorona-phthalene as solvent, the said reactions proceeded smoothly at reflux temperature. The structures of these compounds have been characterized by 1H NMR, UV, IR spectra and GPC. Two compounds have better thermal stabilities than original polyvinyl siloxane. They were used as components of hot-air vulcanizable silicone rubbers. The resulting elastomers showed good mechanical properties (especially high modulus)and heat resistance.
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发布时间：2021-03-19 - 摘要：The syntheses of several redox resins based on the strong-base anion-exchange resins (ch-inese commercial products) was described. The redox capacities of such resins prepared from hydroquinone: catachol, pyrogallol and 2,7-dihydroxynaphthalene are 5.2, 5.3, 5.3, 5.4 and 5.2 meq/g dry resin, respectively, These values are slightly higher than those described in the literatures.Method for measuring redox potential of redox resins, was suggested. The redox potentials of HSR, CSR, PSR were measured which agreed with experimental results of the redox properties. Exchnge properties of the resins with the reducers and oxidizers were also stu-died. Silver from a waste water containing AgNO3 and sulphur from H2S containing gas were recoveed by means of these resins.
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发布时间：2021-03-19 - 摘要：Complex plane analysis for the dielectric relaxation of 1,2-polybutadienes was performed. It has been shown that the dielectric relaxation of 1,2-polybutadienes can be described by Havriliak-Negami equation. Five dispersion parameters for three samples were evaluated from the complex plane plots. The conformational rearrangement motion on the glass transition and distribution of relaxation times of 1,2-polybutadienes were discussed.
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发布时间：2021-03-19 - 摘要：WAXD patters of suggested block copolymers of polypropylene and ethylene-propylene copolymer, PP-EPR and PP-EPR-PP, synthesized by sequential polymerization with δ-TiCl3-Et2AlCl were examined and compared with WAXD of mechanical blends and chain-transfer mixtures of PP and EPR of comparable compositions. The peak at 2θ= 20° for both the copolymers and the mixtures was attributed to γ-modification of PP in EPR. Strong variation in the ratio of diffraction intensities I040/I110 of PP in block copolymers and mixtures was explained in terms of crystallite growth in different directions. Analysis of the spectra and calculation of crystallinity,crystallites size and alttice parameters led to the conclusion that block structure existed in the prepared copolymers.
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发布时间：2021-03-19 - 摘要：In termolecular excimer formation of polyethersulphone (PES) with rigid chain in CH2Cl2 was studied in detail by fluorescence emission spectra. The mechanism of intermole-cular excimer formation was also discussed. The results obtained are:1.The intramolecular excimer of PES in CH2Cl2 can not be formed in normal case because it is rigid chain polymer with aromatic ring on its main chain.2.In very dilute CH2Cl2 solution of PES (below 4.4×10-4M), both of the intermole-cular and intramolecular excimers can not be formed. 3. The intermolecular excimer of PES in CH2Cl2 can be formed when its concentration reach more than 4.4×10-4M.
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发布时间：2021-03-19 - 摘要：The kinetic behaviour of polymerization of butadiene with Ti(n-C4H9O)4-xClx-Al(i-C4H9)3 systems in hexane with variable X values has been studied. The results showed that both the catalyst activity and the apparent activation energy decrease as the chlorine content of the system increases. In the range of AI/Ti value from 15 to 90 (mole ratio), the polymerication rate is first order with respect to the concentration of both monomer and Ti catalyst, but is not much effected by the concentration of Al cocatalyst. The efficiency of the catalysts is only 0.5-1.5%,increasing slightly with increase of the X value,while the relevant propa-gation rate constants decrease greatly. Therefore the polymerization rate reduces as the chlo-rine contents of the systems increase.
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发布时间：2021-03-19 - 摘要：The morphology of the gamma-radiation induced graft copolymerization of hydroxyethyl methacrylate (HEMA) on polyethylene (PE) films was investigated with electrooptical microscope, small-angle X-ray scattering (SAXS). By comparing the structure of domains. It was found that the copolymer consisted of two phases with HEMA several hundred A in size dispersed in PE. matrix. The microdomains change in shape from spheric to rodlike as HEMA-content in the copolymers increases. It was also found that microphase separation cauld lead to ordered arrays of regulardomain phases. The grafted copolymer was detected by SAXS me-thod,and the existence of micro-phase separation was confirmed. X-ray scattering data were analyzed by Tsvaankin-Buchanan technique and the values of long period of the lamellar stru-cture,the thicknesses of the crysatlline and amorphous layers and the linear crystallinity were calculated.
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发布时间：2021-03-19 - 摘要：Catalytic characteristics of poly-γ-(m-diphenylphosphinophenyl) propylsiloxane platinum complex, a silicone-supported triphenylphosphine-platinum complex, for the hydrosilylation of olefins with trimethoxysilane was reported in this work. The hydrosilylation reaction was carried out at 40 or 60℃ under air atmosphere in the presence of the title complex as catalyst. Terminal addition products were obtained, and the yields of them were above 85% in all cases. The catalytic activity of the title complex was higher than that of its homogeneous co-unterpart,tetrakis (triphenylphosphine) platinum complex. No reaction took place when ni-trogen was used as reaction atmosphere.
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发布时间：2021-03-19 - 摘要：Ring opening polymerization of ethylene oxide by using coordination catalysts composed of neodymium 2-ethylhexyl phosphonates-triisobutyl aluminium-water in toluene have been studied. It was found that the catalytic activity of rare-earth coordination catalysts and visco--sity-average molecular weights of PEO obtained both are high. The kinetics for the polymerization of EO with Nd(P204)3 -Al(i-Bu)3-H2O system in toluene at 60℃ has been studied. The overall polymerization activation energy E. measured wat 33.8kJ/mol.and the rate equ-ation could be expressed as Rp=Kp[EO] [Nd(P204)3],where Kp=1.67×10-3mol-1s-1.l.
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发布时间：2021-03-19
Research Article
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