最新刊期
卷 ， 期 1 ， 1981
- 摘要：Long period of irradiated polyethylene strectched and thermally treated under different conditions has been studied by small-angle X-ray scattering.It is shown that long period reduces when the samples are stretched at room temperature. However it increases after thermal treatment. These results can be explained by the breakdown of crystalline structure at first and recrystallization afterwards.
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发布时间：2021-03-19 - 摘要：Pure ferrous ion and benzene diazonium fluoroborate will not initiate the poly-merization of acrylonitrile，while a small amount of copper ion is present，the poly-merization of acrylonitrile will proceed smoothly and its rates of the polymerization will obey the following relationship：The polymerization of acrylonitrile can be initiated by p-nitrobenzene diazonium fluoroborate with the pure ferrous salt containing no copper ion and its rates are affect-ed Very slightly by adding small amount of copper ion．When the concentration of fer-rous ion or the rate of the polymerization is high in these systems，the rates of poly-morization will be proportional to [Fe++]．Results support that the redox reaction is taken place between p-nitrobenzene diazonium salt and ferrous ion．The effects of substituting groups on the para position of benzone diazonium flue-roborate were discussed．
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发布时间：2021-03-19 - 摘要：A new method of block eopolymerization by the use of aromatic tetraazonium salts redox initiators has been proposed. The precipitation polymerization of acrylonitrile in aqueous solution was initiated by the redox initiator of 4,4'-diphenyl tetraazonium fluoroborate and ferrous ion at low temperature (0℃). The polyacrylonitrile linked with diazonium groups and trapped free radicals on both ends by the precipitation polymerization was subjected to block-copolymerize with methacrylic acid or acrylamide. The block copolymers with structures of BAB type were obtained. Similarly acryla-mide was block-copolymerized with acrylonitrile or methyl acrylate in the same way.
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发布时间：2021-03-19 - 摘要：This paper deals with the preparation and polymerization of various fluroine-containing vinylesters under different polymerization temperatures．By measuring the X-ray diffraction pattern of polyvinyl esters and the IR absorbance ratio D915／D850 of polyvinyl alcohol(PVA) derived from its correspondent polyvinyl esters，no distinct dif-ferences in stereoregularity were obsorved among these polyvinyl esters with different length of polar side groups．But the absorbanee ratio D916／D850 inareaaed．i．e．the stereo-regularity of PVA was enhanced with increasing the length of the polar alkyl side groups of its Predecessors．The stereo and polar effect are obvious．Tho temperature dependanee of tactieity was studied in the range of一78 t0 60℃ and it was found that with lowering of polymerization temperature．there is little affeet on the tacticity of polyvinyl esters．Difference in chain regularity do exist in various fluorine containing polyvinyl esters,these are due to lateral interehain order between ester groups and axe not indicativo of the configuration of the carbon chains．
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发布时间：2021-03-19 - 摘要：Low angle laser light scattering is a useful method for the measurement of mole-cular weight of pulymer．In this work a convenient calibration method has been de-vised by using pure organic liquids of known Rayleigh factors to evaluate the instru-ment constant and the background simultaneously for a low angle laser light scattering photometer made in our laboratory．Considering the major background comes from the light scattered in the cell and the probability of stray light passing through the field stop is small，the Rayleigh factor may be rewritten asRθ/n=φ[Gθ/Go)-δ] for small scattering angles，where Go Gθ are electrical signals propotional to the radiant power in the direction θ and in the direction of incident beam respectively，n is reflective index of liquid，δ is a factor related to the background．φ is an instrument constant．A linear relationship is obta-ined from the plot of Rθ/n VS(Gθ／Gθ)of the pure liquids such as toluene，benzen，cyclo-hexane, carbon tetrachloride and chloroform used for calibration．The slope of the straight line is φ and the intercept φδ is related to background．Performance of this instrument and the calibration method has been evaluated by measuring ten poly-styrene samples of narrow MWD and good results were obtained．
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发布时间：2021-03-19 - 摘要：Initiation systems containing amine component are important and well-known in the free radical polymerization of vinyl monomers．Two main types of amine-containing initiation systems were studied in this work．In the case of MMA polymerization initi-ated by BPO-amine (DMT，DHET，DMA) redox systems，it was found that the poly-merization rate and colour stability of polymer for different amine systems were in the following order：DMT≈ DHET>DMA．Thus．BPO．DMT and BPO．DHET are effective intitators．In the case of MEMA polymerization by amine(DMT．DHET, DMA，MBDMA) alone，it was found that the polymerzation rate and percentage of con-version for these different amine systems were in the following order：DMT≥DHET> DMA>MBDMA．The polymerization rate and percentage of conversion also increased with the increase of DAIT coneentration．From the kinetic investigation the rate equa-tion of Rp=K[DMT]1/2 [MEMA]3/2 was obtained，and the overall activation energy of polymerization was calculated to be 34.3 KJ mol-1 (8.2 Kcal mol-1)．Moreover，the polymerization of MEMA was strongly inhibited by hydroquinone．All these evidences indicated that the polymerization of MEMA by DMT alone also follows the typical radical polymerization scheme．and the mechanism of the polymerization was thus proposed．
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发布时间：2021-03-19 - 摘要：Styrene (St) was copolymerized with 2, 2, 6, 6-tetramethyl-4-piperidinyl methacryla-te (MTMP) and the factors influencing this copolymerization system were studied. It was observed that by the use of azo-type initiators (AIBN, ABVN) the copolymerization reaction proeees smoothly, but BPO can not initiate this copolymerization. The St-MTMP copolymer has good heat stability and is soluble in common organic solvents. The copolymer was proved to benon-toxic in animal tests. The structure and properties of the St-MTMP copolymer were characterized by IR,NMR,VPO.
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发布时间：2021-03-19 - 摘要：Both 2，2，6，6-tetramethyl-4-piperidiny-acrylate (ATMP) and -methacrylate (MTMP) are acrylic ester monomers which form stable N-oxyl free radicals rather easily．The binary and ternary copolymerizations of ATMP and MTMP with other monomers were studied．It was found that the relative reactivities of these monomers are in the descending order of St>MA>MTMP>ATMP>VAc．While the rela- tive reactivities of their corresponding radicals are in the ascending order of St·
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发布时间：2021-03-19 - 摘要：The photo-induced etching effect．or development．free vapor photolithvgraphy is a very interesting phenomenon．For determining the mechanism of this phenomenon of cinnamate-type photopolymers，the effects of some factors Dn etching rate have been observed and other experiments have also been made．The results obtained lead to the following hypothesis：When the film of a cinnamate-type photopolymer is irradiated by UV light，a photochemical reaction occurs and the properties of the film are changed．This change enables the film to absorb both HF and H2O from the etching vapor．and a “polymer-hydrofluoric acid solution”can be formed．The solution，which is very different from the mixed gas of HF and H2O，can react with SiO2 rapidly，but the unirradiated film can not absorb the mixed gas easily,hence the rate of etching SiO2 of unirradiated areas is much slower than that of irradiated areas．It is the difference of etching rate be-tween two areas that makes a pattern．The results of our experiments are explained by this hypothesis．
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发布时间：2021-03-19
Research Article
- 摘要：This work reveals that the parameter of molecular size distribution for equilibrium polymerization is relative to the equilibrium constants and the initial concentrations of initiator and monomer. The following Equation is established to describe the relationship between parameter a and the initial reaction conditions:andThen, we can control the average molecular weights and dispersion of the polymers generated in equilibrium polymerization by means of regurating the proportion of monomer and initiator pourd into reactor.
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发布时间：2021-03-19 - 摘要：The direct determination of crystallinity of polypropylene fiber by inverse gas chromatography has been studied．The columns were pa~ked with physical mixtures of GC support and fiber seetionS in powder form．which was obtained by cutting the fiber samples with a pair of scissors．This treatment eliminates the need for solution coating or heating of the column packing，which may influence the erystallinity in some degree．We used a column with 3 mm O.D. to hasten the temperature equilibrium． so that the reliability of the extrapolated term of Guillet's equation．which was used to calculate the crystallinity，could be improved．The values of crystallinity obtained by this method are not influenced by such factors as various probe molecules，the length of column and the content of polymer．The results of eight samples obtained are consist-net with those detcrmined by X-ray and density methods．
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发布时间：2021-03-19 - 摘要：The structure of cashew nut shell liquid in the modified phenol-formaldehyde resin has been investigated by infrared spectroscopy. The Mark-Houwink expressions for the modified phenolformaldehyde resin in acetone at 250℃ were found to be [η] = 6.93 × 10-2 Mn0.59 for fractionated samples with a molecular weight range of 710-2740 by viscometry and vapor pressure osmometry.The parameter a of Mark-Houwink equation and Huggins constant Kn were discussed.
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发布时间：2021-03-19 - 摘要：A new epoxide of β-(2,3)-epoxypropoxyethyl nitrate was prepared, characterized and polymerized with BF3Et2O-HO(CH2)4OH as a catalyst system to yield a new homo-polymer and a new copolymer with tetrahydrofuran. These prepolymers are viscous oil having reactive hydroxyl groups which are readily vulcanized with toluene diiso-cyanate and 1,2,6-trihydroxyhexane in the presence of a small amount of ferric acetonyl acetonate to produce rubbery elastomers with rather good elasticity in low temperature.
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发布时间：2021-03-19 - 摘要：The thin layer ehromatography (absorbent: Silica-gel; developer: chloroform-benzene=2:1) has been applied to the determination of molecular weight of carbopbenoxy terminated aromatic polyesters. It is as accurate as spectrophotometry.
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发布时间：2021-03-19 - 摘要：The sequence structure of butyllithium catalyzed SBS block copolymers polymerized by two-step feed method has been studied. The results were shown below:(1)The aromatic proton resonance of non-block styrene of SBS does not show a single peak but consists of two peaks in 250 MHz NMR spectra. By using ethyl benzene as a model compound, the phenyl resonance peak of non-block styrene of butadiene-styrene was assigned.(2)If the non-block styrene and 1, 2-butadiene contents are both below 10%, their low glass transition temperatures Tg are all below -69℃ obtained from dynamic me-chanical temperature spectra.
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发布时间：2021-03-19 -
STUDY OF POLYBUTADIENE CHAIN MICROSTRUCTUREBY 13C-NMR——The S-Resonancc Peak of the C-1,4-VCH Linkage
摘要：A resonance peak of cis-1, 4 to vinyl placement in polybutadiene has been found by 13C-NMR and designated as S-peak. The finding of the S-peak has further clarified the various polybutadiene microstructures, and its significance in the study of the chain microstructures of polybutadiene is pointed out.- 13
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发布时间：2021-03-19
Research Bulletin
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