最新刊期
卷 ， 期 2 ， 1980
- 摘要：The moleeular weight distribution of three kinds of epichlorohydrin elastomers has been studied by using a simple GPC colum．The column is packed with porous silica beads with an efficiency of more than 2000 plates per metre．It has been shown that the molecular weight distribution of the epiehlorohydrin homopolymer made by the catlyst system of i-Bu3Al-H3PO4-H2O dimethyaniline is broader than that made by the catalyst system of i-Bu3Al-H3PO4-benzothiazole sulfenamide．The polydis-persity is between the range of 3—6．The molecular weight distribution becomes narrower and the molecular weight is lowered during the milling of the elastomer．The polydispersity increased with the inc rease of conversion，the increase of mono-mer concentration，the decrease of polymerization temperature．The change of the molar ratio of dimethylaniline to the eatlyst greatly effects the polydispersity of the copolymer．
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发布时间：2021-03-19 - 摘要：The present paper describes the stereoregularity of poly-2, 2, 3, 3-tetrafluoropropyl methacrylate (PTFPMA). PTFPMA is prepared by free radical polymerization with benzoyl peroxide as initiator in toluene at 60℃. Hydrolysis of PTFPMA in concentrated sulfuric acid gave a water soluble polymethacrylic acid, and reesterification with diazomethane grave polymethyl methacrylate. The polymethyl methacrylate was confirmed to be an ataetie polymer by NMR and IR analysis. These results also indieate that PTFPMA is an atactic polymer.
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发布时间：2021-03-19 - 摘要：Poly (tetrarnethylene terephthalate)-poly (tetramethylene ether) block copolymers with various contents of hard segments and with soft segments of various molecular weights were prepared. It was shown, that contents of hard segments and molecular weights of soft segments affect the. block copolymerization reaction, especially, the formation of homopolymer. The short hard segments can crystallize even with only 2-4 formal units. The polyester-polyether multiblock copolymer with 20 wt% hard segments is melt-spun to give elastic fibers with good elastic recovery.
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发布时间：2021-03-19 - 摘要：The effects of three kinds of catalyst, such as zinc acetate, potassium titanyl oxalate and titanium dioxide, on the block copolymerization of polyether-polyester were studied. It was found that titanium dioxide possesses not only good catalytic action, but also improves the thermal stability of the resulted copolymer.
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发布时间：2021-03-19 - 摘要：The crystallite dimensions of a new solvay type catalyst for propylene polymerization were determined from the data of breadth of X-ray diffraction lines at half peak intensity. The crystallites have the size of about 100 A and they are smaller then those prepared by other methods. Their catalytic activity increases linearly with decreasing crystallite size.Surface area and pore structure of the catalyst were determined by elution chro-matographic method on model ST-03 analyzer. Our results showed that such catalyst possess high specific surface area and large pore volume and has both large and fine pores. Therefore,active centres can be fully available.
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发布时间：2021-03-19 - 摘要：Butadiene-isoprene copolymers (BIC) synthesized with rare-earth catalysts are characterized by high cis-1, 4-butadiene and isoprene units in microstructures, and their vulcanizates have good low-temperature properties under proper B/I ratios. This work was undertaken to study the properties of compounded rubber and vulcanizate of BIC (sample Jin-20) by using two different vulcanization systems, (CZ-S) and TMTD. By comparing with that of IB and BR similarly polymerized with rare-earth catalysts, it has been found that Jin-20 has some notable features.
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发布时间：2021-03-19 - 摘要：In the absence of added salts, the viscometric behavior of Na-salts of sulfonated polysulfone in DMF has been experimentally studied. A new empirical equation expressing the relationship between reduced Ariscosity and concentration of polyelectrolyte solutions is proposed as followingWhen this equation was applied to our experimental data and to that of Fuoss', the results obtained were satisfactory. With the electroviscous effect and extension effect of polyion, this empirical equation has been discussed.
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发布时间：2021-03-19 - 摘要：With the method of dilution in constant concentration of added salts, viscosities of Na-salts of sulfonated polysulfone in DMP containing NaNO8 of different concentrations have been measured experimentally. Based on treatment of experimental data, an empirical equation is deduced as followingIn this equation, the first term represents the relationship between reduced viscosity and solution concentration in the absence of added salts while the second term represents the correction on reduced viscosity in the presence of added salts. It can be predicted satisfactorily by this empirical equation how the concentration of added salts effected on the curve of reduced viscosity, Furthermore,this equation did show obviously how intrinsic viscosity of sample used varied with the concentration of added salts.
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发布时间：2021-03-19 - 摘要：The calibration coefficients K were determined by using nine pure compounds in the molecular weight range of 178 to 716 in benzene, chloroform and methyl ethyl ketone at several temperatures in two apparatus of different thermistor assembly. K was found to be constant in the molecular weight range of solute studied. In order to investage the effect of structure of instrument on the results of measurement, several polymers of different molecular weights ranging from 1200 to 3.5×104 were measured. Approximatly the same results were obtained. It has also been found that the time required to reach the steady state is qpparently depend upon the na-ture of solvents.
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发布时间：2021-03-19 - 摘要：3-nitropropene 1,2-epoxide was successfully polymerized and eopolymerized with tetrahydrofuran in the presence of boron trifluoride etherate-butanediol (1,4) as a catalyst system to yield polyethers containing terminal hydroxy groups and nitrome-thyl groups in side chain. The viscous oily prepolymers can be satisfactorily crosslin-ked with toluene diisocyanate and glycerine to form rubbery elastomers. Some characteristic properties of the prepolymers and crosslinked polymers have been studied.
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发布时间：2021-03-19
Research Article
- 摘要：A series of M-S low conversion copolymers were prepared by free radical polymerization and their IR spectra were measured.The 1149.5 cm-1 band which is related to a skeletal vibration coupled with CH deformation vibration in PMMA, is shifted to lower wave number with a decrease in the content of MMA in the copolymer.Two results can be drawn:(1) The correlation curve between this band position and the sequence length of M unit in the copolymer is obtained.(2) The displacement of wave number of this band is approximately propop-tional to FSMS which is defined as the mole fraction of SMS in trids of SMS.MMS.SMM.and MMM. Other environmental-sensitive bands which depend on sequence distribution were also discussed.
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发布时间：2021-03-19
Research Bulletin
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