最新刊期
卷 ， 期 3 ， 1986
- 摘要：An analysis of unconstrained elastic recovery of viscoelatic fluids following the release of stress is presented and a new equation relating die swell ratio to recoverable shear strain is developed. The prediction from the new equation was compared with the experimental data and with the theories of Graessley et al. and Tanner.
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发布时间：2021-03-19 - 摘要：Photopolymerization of MMA was studied Kinetically using thioxanthone (TX)/ triethylamine (TEA)/oxygen system as initiator. The various factors influencing the polymerization rate were studied. Experimental results shown that polymerization rate is directly proportional to (TX)0.1 (TEA)0.3 and (MMA) and markedly depencent on the nature of solvents, as a results of the proximity effect of the lowest energy nπ and ππ excited states. The accelerating effect of oxygen in this system, especially in the presence of stearic acid resulted an increase in the quantum yield to 2.3 times.
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发布时间：2021-03-19 - 摘要：Melt blends of poly (ethylene oxide) (PEO) and poly-(vinyl acetate) (PVA) were prepared and studied by Torsienal Pendulum Analysis (TPA) and Fourier Transform Infrared (FTIR)．Two glass traditions are found in these blends．The lower Tg cor-responds to the pure PEO. The segmental motion in the pure PEO The dependence of the position and broadness of the higher Tg on composition of the．blends indicates that the two compo-nents are vompatible in the amorphous phase with micro-heterogeneity．These Tg values observed from mixed PVA／PEO phase are ranch higher than that caleutated from Fox equation．The comparision of the blends quenched and annealed from melt implies that PVA mixed with PEO at the segmental level on molten state and the deviation of Tg values from Fox equation could be due to changing the blend's composition by erystal-lization of partial PEO component．Further indication that the hiends are compatible down to the ecBle of chain segments and there ale specific interactions between PVA and PEO molecules from came the analysis of FTIR speetra of the blends and the so-lution of PVA and organic solvent Diethylene Glycol Dimethyl Ether．
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发布时间：2021-03-19 - 摘要：The series of copolyesters were prepared from Chloro-Hydroquinone or Methyl-Hy-droquinone, Terephthalic acid and two kinds of comonomere, which could provide kinking and bending in chain: Oxy-4,4'-diphenol and Isophthalic acid. The four-components copolyesters in certain range of compositions have low melting temperature, steady mesophase in a broad temperature range and fiber-forming tendency. This report is focus on the relations of molecular composition-transitions-liquid crystallinity and fiber-forming tendency,and the morphologic features of mcsophase.
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发布时间：2021-03-19 - 摘要：The syndiotaetic 1,2-polybutadiene-1，4-polybutadiene copolymer is crystalline with a m.p. of 205—-210℃．independent of the content of 1,2-unit．It is considered that the copolymer is block in nature．The DSC peak temperatures (Tp) for thermo-oxidation of a low 1,2-content (12一 20％) sample and a high one(95一100％) are 185 and 200一240℃，respectively．It is believed that the double bond in side group is more stable than that in the main chain．The difference in stability,between the two kinds of double bond can be explained by the facts that：1) the inner．double bond has four a-hydrogens，but the outer one has only one；2) the,block of 1,2-unit is crystaUine below 203℃，whereas that of 1,4-unit is amorphOUS even at room temperature．The activation energy, exothennal effect of thermo-oxidation for high 1,2-oontent polybutadiene of various conversion is also described．
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发布时间：2021-03-19 - 摘要：Using the atomic scattering factors approximation expression and computer, the atomic scattering factors were calculated. Then the correct factors for fotar main crystal planes of the syndioitactic 1,2-PBD were calculated. The correct factors were clearly defined. X-ray crystallinity formula was found.
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发布时间：2021-03-19 - 摘要：The unperturbed dimensions of macromolecules have been measured by GPC coupled with a capillary viscometer. Polymer were fractionated by GPC column. The capillary automatic viscometer determines the intrinsic viscosity of the fraction. Using calibration and/or universal calibration, the molecular weight is obtained. In a number of theoretical equations, the unperturbed parameter, Zθ is obtained from the intercept of the plot off intrinsic viscosity and molecular weight.The results agree well with the corresponding values measured from the convention-al method and GPC coupled with a Low=Angle laser Light-Scattering Photometer.
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发布时间：2021-03-19 - 摘要：Proeedures are developed for the determination of fluorine and phosphorus in poly-mers and organic compounds iby titration with Nd(NO3)3-EDTA after decomposing the sample by O-flask．An amount of sample eorresponding to approximatoly 1 mg of flu-orine is decomposed and absorbed in an O-flask containing an excess of 0.01 M Nd3+ (NO3)3．The absorbing liquid is boiled for 3 minutes．After being allowed to eool，a pH=5.5 buffer is added．In the presence of xylenol orange．the mixture is titrated with 0.01 M EDTA．The proeedure for determining phosphorus is the sanle as described above．hut preeipitation reaction of NdPO4 is earried out in pH 5.5 after eliminating CO2．If sam-ple contains F and P，PO43-in the solution containing F- can be detemined after eli-minuting F- by adding HNO3 and concentrating solution to dryness，and the percenta-ge of F can be found after determining the total content of F and P．Determinetion procedure of total content is the salne as F-，but buffer is added while the mixture is hot．The maximum error of determing P is±0.20％ and F is+0.30％ except high flu-orine or fully flucrinated eompmmds which give values approximately 0.50％ lower than calculation．
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发布时间：2021-03-19 - 摘要：The thermal stabilites of silicone gums containing cyclodisilazane,(SCD), E=Me, Ph, Were studied in comparison with methyl and phenyl silicone gum by the method of TGA. IGA. GC. and GC-MS. The initial temperature of the weight loss of SCD is 150-200℃ higher than that of methyl silicone gum, the wedght loss is 10-20 times less than that of methyl as well as phenyl silicone polymer. Based on both the GTA and the IGA data, the presence of cyclodislazane in SCD enhances the resistance of the main chain to degradation and the weight loss remains almost the same as the number (x) of Me2SiO groups in SCD changes. Outstanding stability of this material makes them to be used potentilly as high-temperatuse elastomers. Accoding to analysis of the decompsed products a two steps mechanisum of degradation is proposed.
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发布时间：2021-03-19 - 摘要：Homopolymer and copolymer PAN precusors can be used in the cartoon fiber manufacture process. These two kinds of precusors have different machanism during oxi-dation reaction.The phenomena which take place in the oxidation process for two kinds of precusors are investigated by means of DTA, thermal mechanical measurement, ESR which measures the concertration of free redicals and acoustic propagation method which measures the variation of Young's modulus. It was observed that homopolymer PAN precu-sor is mainly cyclized by free radical process,but since this sample has already partly hydrolyzed,so that it also can be induced by ion transfer process. Meanwhile for copolymer precusor,it seems that ion transfer process is the main one.
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发布时间：2021-03-19 - 摘要：The resin solution of NA capped "PMR" type polyamideimide (PAI) was prepared frpm bicyclo [2. 2. 1] hept-5-ene-2,3-dicariboxylic acid ethyl ester, 1,2,4-trimellitic acid-2-(or-1-) ethyl ester and 4,4'-diaminodiphenyl methane in ethanol. This resin solution is specially suitable for the preparation off composites. The flexural strenght of the glass fabrics reinforced plastic was 6000-7000 Kg/cm2 (RT) and 4000-4400 Kg/ cm2 (260-300℃), respectively. The result of isothermal ageing for 800 hours indicated that this composite can be used at 260℃. The mechanism of the formation of poly-amide-imide was discussed by using appropriated model compounds.
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发布时间：2021-03-19 - 摘要：The osmotic pressure of Na-salts of sulfonated polysulfone with or without added salt were measured by rapid dynamic osmometry in DMF at 25±0.002℃. The phero-mona of experiment have been discussed. A method of determining molecular weight of sulfonated polysulfona with added salt above 0.07 N by Osmometry has been established.
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发布时间：2021-03-19 - 摘要：The Thermal Field-Flow fractionation (TFFF) method was used to determine the elution volume of a series of star branched polystyrene having different number of arms but the same molecular weight and polystyrene standards with narrow distribution whose molecular weight ranged from 5.0×104 to 86×104. Results were obstained by measuring at two) temperature differentials (△T=30℃ and △T=50℃) in THF. These star branched samples were also measured by means of GPC method. Comparison of the Vr-M relationship obtained from TFFF and GPC showed that the displacement of Vr-M curves for star branched and linear polystyrene is larger in TFFF than in GPC.The difference is caused by the different mechanism of separation for these two methods. As the controlling factor is the hydrodynamic volume of the polymer chain in solution for GPC,it is the diffusion coefficient of polymer molecules for TFFF.The experimen-tal results indicate that the influence of variance of chain structure on diffusion coef-ficient is stronger than that on the hydrodynamic volume and that TFFF technique maybe used as a method for characterizing branching oof polymer molecules. For this purpose a proper theroetical model and more accurate experiments are needed.
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发布时间：2021-03-19
Research Article
- 摘要：The catalytic effect of MoCln(OE)4-n-(i-Bu)2AlOPh on polymerization of butadiene in hydrogenated gasoline is studied (B is alkyl, cycloheptyl, phenyl of C4-16). In the system, the solubility and the catalytic activity of the catalyst are not related to the number of carbon atom in R group whether odd or even. The B group with primary and secondary carbon atom have a rather great influence on the catalytic activity. When B is an alkly, the catalytic activity incerases and the range of Al/MO values that keep higher conversion of butadiene is broadened with increasing the size of R group. The content of 1,2-units in the polymers did not change with the size of R group.
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发布时间：2021-03-19
Research Bulletin
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