最新刊期
卷 ， 期 1 ， 1982
- 摘要：For the anionic polymerization of polar monomer initiated by arbitrarily function-al initiator with instantaneous initiation and monomer termination，the expressions of molecular weight distribution，average degree of polymerization，functionality distribu-tion and average functionality of the polymer formed have been derived by means of non．steady state method．The maximum amount of the monomer which will be con-sumed during the polymerization under consideration was discussed．A theoretical method has been established．with which the molecular weight distribution and the values of other molecular parameters can be calculated from the monomer conversion and initial conditions of the polymerization．It was shown that with a few exceptions．the theore-tical curves of molecular weight distribution resulted from numeric computation possess double peaks．Such a process is particularly true for the anionic polymerization of methyl methacrylate in polar solvents and at lower temperature．
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发布时间：2021-03-19 - 摘要：Copolymerizations of acrylonitrile (AN) with dimethylaminoethyl acrylate (DMAEA), dimethylaminoethyl methacrylate (DMAEMA), and methacrylonitrile (MAN) with DMAEMA in dimethylsulfoxide at 60 ± 0.1℃, initated by azobisisobu-tylnitrile have been studied.The compositions of AN-DMAEA copolymer at any degree of conversions in polymerization have been also determined and the results are fairly in agreement with the calculated values of the Skiest equation.
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发布时间：2021-03-19 - 摘要：It has been shown that the free volume fraction at Tg is not a universal parameter for linear polymers of different molecular structure[2]．The reason is that the volume expansion at Tg is partially contributed from the change of the numbers of eonforma-tions of isolated molecular chains due to internal rotation．In this paper，glassy trans- formation was connected with internal rotation of isolated molecular chains，and the relationship between free volume fraction of polymers at Tg and energy E of rotational isomerization of isolated molecular chains was formulated，The values of calculated from the above formula are in good agreement with those published in the literatures．Thus，the method described in this paper call be used to estimate a varameter for the flexibilitv of isolated molecular chains．
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发布时间：2021-03-19 - 摘要：F-30 - Copolymer of chlorotrif luoro-ethylene and ethylene is an alternative co-polymer. Lrradiated F-30 at certain condition it crosslinks readily. After crosslinking its mechanical properties are improved remarkedly.The molecular weight of F-30 has not been reported before. By using Flory's theory of elasticity, we determine the shress-strain curre of F-30 at the temperature above its melting point and find out the crosslinking 6 value to be 1.4. On the basis of Charlesby-Pinner relationship we find ou the dose of gelation (Rgel) of crosslinked F-30 to be Rgel 1.6 Mrad. From the obtained data, we can calculate the weight average moleculer eight of F-30 to be about 2.1×105.
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发布时间：2021-03-19 - 摘要：The segregation on crystallization of polyester-polyether segmented copolymer in bulk has been observed, copolymer molecules segregate and form crystals of different melting point located near 140℃ and 160℃. Fraction of different melting point can be separated by thin layer chromatography. Eesults show that molecules of the higher melting point fraction have larger hard segment length and lower hard segment content, in contrast, molecules of the fraction of lower melting point have shorter hard segment length but more hard senment content. The heterogeneity in composition of the copolymer is supposed to be resulted rom the poor compatibility between the components of the polycondensation system.
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发布时间：2021-03-19 - 摘要：The photo-stabilizing eftect of 1，2，2，6，6-pentamethyl-4-hydroxy-piperidine (PMP) in isooctane solution．containing hexadecene-1 and di-t-butyl peroxide．has beern investigated．It is shown from the experimental data that the photostabilizing effee-tivenesa of PMP is approximately the same as 2，2，6，6-tetramethyl-4-hydroxy-piperidine (TMP) and slightly higher than that of 2,2，6，6-tetramethyl-4一hydroxy·piperidine-N-oxyl (NO)，and that PMP，as well as TMP，produces N-oxyl in the photostabilizing process of PMP and the concentration of NO produced changes through a maximum-There is a difference related to the production of NO between PMP and TMP．In the ease of PMP the rate of cumulation of NO is slower and the maximum value of NO concentration is lower than that in the ease of TMP．It has been also found in experi-ments that a stable intermediate．1，2，2，6，6．pentamethyl-4-hydroxy．piperidine-N-oxide (PMPO) is produced in photostabil．izing process of PMP．From the above mentioned facts it is suggested that the stabilizing effect of PMP is aeeomplished by a two-step mechanism in which PMP is first transformed into its oxide PMPO．and then PMPO is further transformed into NO．
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发布时间：2021-03-19 - 摘要：We have studied the catalytic systems, Ti(OE)nCl4-n, supported on MgCl2-EB (EB stands for ethyl benzoate) for stereospeeific polymerization of propylene. In this paper, the influences of different kinds and number of -OR group on the catalytic function were reported. The result showed that all of these catalysts are in high activity for polymerization of propylene and high isotactic structure of polypropylene. The activity of n-C5H13OTiCl3 is the highest among them. Because of the steric hindrance, the increase of the number of --OR group leads to decrease catalytic activity and reguarity, When alkoxyl groups were introduced in the titanium active species,the molecular weight of the polymer was decreased obviously.
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发布时间：2021-03-19 - 摘要：We have found that DMT would act as active initiator for the photopolymeriza-tion of aerylonitrile．The sensitization eft ect of various aromatic tertiary amines on the photoplymerization of AN has been studied．The electro．positive group on the benzene ring will increase the activity of the amine while the electro—negative group will decrease it．The activities of various amines have been found in the following deereas-ing order：N，N-dimethyltoluidine(DMT)>N，N-d'methyl．J3-hydroxyethyrItoluidine(DHET)> N，N-dimethylaniline(DMA)>N，N．dimethylamino ben zaldehyde(DMB)>N，N． dimethyl-p-nitroaniline (DNA)．The mechanism of photoplymerization of AN initiated with aromatic tertiary amine belongs to the free radical type in nature，and the rate of polymerization is proportional to the 0.66th power of concentration of amine． Within the range of 10-2---10-4 M in the concentration of amine the reciprocal of average degree of poly-merization is proportional to the 0.5th power of eoneentration of amine．The tentative mechanism of initiation has been proposed．The formation of initiating radical speeies may be ascribed to the decomposition of the excited charge transfer complex (exciplex) from the excited state of aromatic tertiary amine with the monomer molecule of aerylonitrile．
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发布时间：2021-03-19 - 摘要：In order to improve the toughness of polyethylene (PE) necessary for its use as insulation covering of telephone cable for battle field service，an investigation on the blending of PE with poly (eis-1，4-butadiene) (PB) was carried out．This paper presents a study on the influence of the composition of the blends on their supermoleeular structure and properties．Optical microscope，electron microscope，x-ray diffraction and optical depolarization were used for analyzing the supermoleeular structure，while resistance to repeated folding was used as a measure of flexibility of the blends． It is shown that before PB changed from dispersed phase to continuous phase．the higher the content of PB，the better the flexibility of the blends，and that the flexibility of the blends could be increased to 7.6-一11.5 times of that of PE at optimum blending compositions，regardless of whether the PE used was linear，branched or of different molecular weight．
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发布时间：2021-03-19 - 摘要：In aqueous nitric acid solution, the polymerization of acrylonitrile initiated by metallic magnesium have been studied. The results show that the rate of polymerization is independent of the amount of magnesium used; when the concentration of nitric acid is higher than acrylonitrile, the equation of polymerization kinetics may be expressed asThe copolymerization of acrylonitrile and methyl acrylate supports a free-radical mechanism for this polymerization.
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发布时间：2021-03-19
Research Article
- 摘要：The microstructure of EPDM-CR polyblends was investigated with electron and phase-contrast microscope. It was shown that the relative affinity of EPDM and CR for carbon blacks is different.By Comparing the structure of network domains, we found that carbon black displacement can occur in EPDM-CR polyblends systems. Structure of non-homogeneity domains is dependent upon the blending method and the carbon black content.
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发布时间：2021-03-19 - 摘要：A new method of grafting acrylonitrile onto viscose filament with manganese (IV) as initiator has been developed under proper conditions, higher graft increment could be obtained by keeping homopolymerization at its minimum. The results obtained from X-ray diffraction, microscopic and SEM studies showed that copolymerization mainly occurs in low ordered region.
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发布时间：2021-03-19 - 摘要：The low rate of tetrahydrofuran polymerization initiated by organic halo-compound and sodium perchlorate is attributed mainly to the relatively slow reaction of the two components of the catalyst. The rate can be raised by increasing the amount of sodium perchlorate. The influence of the amount of acetic chloride-sodium perchlorate catalyst on the hydroxyl functionlity of oligomer, obtained by hydrolyzing the product of polymerization was studied.
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发布时间：2021-03-19 - 摘要：The structure of polymethylphenylsilaza-siloxane-Pd complex catalyst has been investigated by X-ray photoelectron spectroscopy (XPS). The experimental results indicated that the complex is formed by coordination of two lone pairs of electrons on two nitrogen atoms in polymethylphenylsilaza-siloxane to one palladium atom in palladium dichloride. The inactivation of the complex in the hydrogenation of olefines is due to the destroy of the complex and the reduction of Pd(Ⅱ) to Pd(0).
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发布时间：2021-03-19
Research Bulletin
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