最新刊期
卷 ， 期 3 ， 1981
- 摘要：In this paper a distribution function of polymerization degree is presented. This distribution function contains three parameters a, b and P0. When a equals 1 the distribution function becomes schulz distribution. Because the distribution function contains three parameters it possesses broad applicability. The distribution function has been tested for eleven kinds of polymers. It is found that the function proposed by the present authors provides good agreement with experimental data. Analytical expressions of different average polymerization degree have been obtained.
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发布时间：2021-03-19 - 摘要：The photophysical behavior of polystyrene sulfonate acridine orange system has been studied. It was found that the fluorescence intensities of acridine orange are strongly dependent on the ratio (P/D) of the dye and the polyelectrolyte used.The maximum fluorescence intensity was observed at (P/D) =100. After correction, this value agreed with the result obtained by Fox et al. in study of energy-transfer of poly(styrene-Co-l-vinylnaphthalene). It indicated that the energy migration occurred efficiently in the polyelectrelyte-dye complexes. In this paper,the quenching of fluorescence of acridine orange by methylene blue was also studied. The enhancement of quenching effect has been observed after adding polyelectrolyte.
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发布时间：2021-03-19 - 摘要：The following compounds have been synthesized by Diels-Alder reaction in 96% yield.Compounds Ⅰ, Ⅱ were used as additives for compounding of silicone rubber. The resulting elastomers showed good thermal stabilities and fair mechanical properties after aging at 280℃ and 300℃ for 24 hours respectively.Compounds Ⅰ, Ⅱ were used as crosslinking agents for hardening of room temperature vulcanizable silicone rubber. The resulting elastomer had good heat resistance also.Two kinds of heat resistant silicone paints were prepared from H3BO3 and com-pounds I or II They showed good thermo-oxidative stabilities after thermal aging at 500℃ for 6 hours.
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发布时间：2021-03-19 -
THE RELATIONSHIP BETWEEN NUMBER AVERAGE MOLECULAR WEIGHT AND VISCOSITY OF POLY (P-PHENYLENE SULFIDE)
摘要：A micro method of determining the number average molecular weight (Mn) of PPS had been established, A AgCl-Ag2S Solid-film selective ion sensitive electrode was used to determine the molarity of chloride ion, after PPS was decomposed in an oxygen flask and the absorption solution was kept to a constant volume. The samples had not been fractionated, hence, the standard deviation between the parallel run was about ± 10%.The relationship between M, and melt viscosity of PPS at low shear rate is as follows.and the relationship between Mn and intrinsic viscosity of PPS is as follows,the unit of n and [n] is in poise and ml/gm respectively.- 2
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发布时间：2021-03-19 - 摘要：Relative thermal stability of polyimides has been investigated by TG．In order to evaluate roughly the heat resistance of polyimides from the data of relative thermal stability according to the mechanism of oxidation-dehydrogenation，we tried to establish a quantitative relationship between chain structure factor and polyimides has been pro-posed as follows：where thermal index T20．000 is the temperature，at which the material can be used for life time 20，000 hrs；KH is the hydrogen fraction，which equals to number of hydrogen atoms divided by the number of total atoms in repeating unit of the macromolecule；a，b are constants．The kinetics of thermal and thermo-oxidative degradation has been discussed．Apparent activation energy of thermo-oxidative degradation of polyimides is not cons-rant throughout the whole process，but decreases as the reaction proceeds．The activa-tion energy of thermal degradation remains constant．
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发布时间：2021-03-19 - 摘要：TiCl4 was reduced with ethylaluminum sesquichloride in n-hexane. The reduction product was treated with diisoamyl ether and by heating at 35℃ in TiCl4 solution. The comlex catalyst thus obtained gives high catalytic activity and stereospecificity for polymerization of propylene. The compositions and structure characters of the reaction product in the preparation process of catalyst were investigated. Moreover, the mechanism of the transformation of TiCl3 at the lower temperature was discussed.
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发布时间：2021-03-19 - 摘要：The crystallinity of soft" segments of polytetramethylene ether glycol (PTMEG)-based segmented copolymers was investigated by infrared spectroscopy and dilatometry. Results showed that the melting point and crystallization rate of soft segments decraese with decreasing of the content of the PTMBG component in polyether-polyester seg-. mented copolymers. However the soft segments of polyether-polyureaurethane segmented copolymers do not tend to crystallize even at low temperatures (e.g. - 28℃ 30 min.), due to the hydrogen bond interaction between NH nad C--O--C. In addition,high draw ratio wil increase the melting point and crystallization rate of the soft seg-ments for both types of segmented copolymers.
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发布时间：2021-03-19 - 摘要：The reaction rate of bis(2，3-epoxycyelopentyl) ether (W-95) with methylene diani-line (MDA) was determined and compared with that of bis．phenol-A diglycidyl ether (E-54) with MDA by means of infrared spectroscopy，D．C．conductivity measurement and chemical analysis．The apparent energies of activation of the two reaction systems are appoximately equal．If the reaction rates of primary amine and secondary amine with epoxy group of W-95 are k1 and k2，and that of E-54 are k1 and k2 respectively then the reaction rates of k1：k2：k1：k2 were found to be 200：22：20：1．The curing process of a system composed of a mixture of W-95 and E-54 (50／100，W／W) with MDA as curing agent was studied．It has been found that at the early stage of the reaction，the ring-opening of the E-54 epoxy groups is initiated by the primary amines with the formation of linear polymeric chains．Then，the secondary amines in the polymer molecules react further with the epoxy groups of the W-95 to form crosslinked chains．
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发布时间：2021-03-19 - 摘要：The crosslinking reaction of bicyclo[2．2．1]hept-5-ene-2，3-dicarboxylic anhydride capped polyimide by using N-phenyl-bicyclo[2．2．1]hept-5-ene-dicarboximide (I) as the model compound was studied．It is found from the changes of the conversion and the molecular weight of the polymers with reaction temperature and time that endo-I could be polymerized above 275℃ and the polymerization tended to the completion at 800℃ for 2hr．NMR spectra of endo-I polymers show that the following structural units were present in the pulymer：The contents of different types of double bonds in the polymer could be determined semi-quantitatively by NMR spectroscopy and the bromine addition method．The ex- perimental results indicated that the average molecular weights of the polymer are 800一1000 and the total contents of double bonds are 1.00一1.25 per molecule．while the con-tents of double bonds of cyclopentene type are smaller than 0.5． Under the same reac-tion conditions the structure of the polymers from endo．and exo-I is similar．As a result，the following mechanism of polymerization was proposed．The retro Diels-Alder reaction took place at first on heating I．The active centres were produced above 275℃．then the chain growth reaction was followed．The trasformation of confi-guration．rearrangement and different paths of chain growth reactiOIlS occurred during the polymerization．The chain termination was caused mainly by disproportion reactions．
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发布时间：2021-03-19
Research Article
- 摘要：Literature gives only general information about SBS copolymer formed by two-stage synthetic process using mono-functional group alkyl lithium as initiator. The present article studies preliminarily the structure and properties of SBS by two-stage synthetic process using cyclohexane as solvent, n-BuLi as initiator and THF as additive. Results show when the middle block styrene content is controlled at around 8%, the properties of the copolymer is superior than those given in literature and similar to the Shell products Cariflex TR-1101.
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发布时间：2021-03-19 - 摘要：The effect of presence of polystyrene sulfonic acid on the polymerization of acryla-mide have been studied. It was found that the rates of initial polymerization of acryl-amide greatly increased with increasing of concentration of polystyrene sulfonic acid, and the maximum value was obtained when [PSSA] : [AM] =3:1. The energy of activation of the polymerization was determined. It was found that the energy of activation decreased from 12.3 kcal/mole to 9.8 kcal/mole due to the presence of matrix polystyrene sulfonic acid. When the insoluble polystyrene sulfonic acid was used as matrix instead of soluble one the effect was considerably decreased.
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发布时间：2021-03-19 - 摘要：The photochemical catalytic properties of tris-2, 2'-bipyridine ruthenium complex, Ru(bipy)32+, in splitting of water, have received extensive study. In this report, we describe the preliminary results of synthetic work. A new polymeric bipyridine ruthenium complex was synthesized and its spectra were discussed.
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发布时间：2021-03-19 - 摘要：In this study, the process of photosensitization oxidation of poly (styrene-co-2, 2, 6, 6 tetramethyl-4-piperidinylmethacrylate) and 2, 2, 6, 6 tetramethyl-4-piperidinol were compared. It was shown that, the copolymer stated above can accumulated more quantity of stable free radical than another one under same condition.In the experiments of quenching effect for fluorescence of pyrene, the effect of copolymer is similar to the low molecular compound.
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发布时间：2021-03-19
Research Bulletin
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