最新刊期
卷 ， 期 6 ， 1990
- 摘要：The microdomain structure and domain packing mode in polydisperse PMMA-b-PTHF diblock copolymer have been'studied with SAXS and TEM techniques The copolymer composition is 48/52, and its heterogeneity index is 1.99. We found that the morphology of domain is spherical micelle which is also heterogeneous in size, instead of lamellar microdomain. The mode of microdomains packing is nearly disordered arrangement instead of macrolattice. Our results show that the theory on the morphology formation of monodisperse block co-polymer is not alwayssuitable for thepolydisperse block copolymer.
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发布时间：2021-03-19 - 摘要：The glass transition temperature (Tg) and unperturbed demensions of PMMAs with Bernoulli distribution of stereoregular diads were measured. It was found that T, of PMMA depends not only on their tacticity but also on the distfibution type of the diads. Therefore, the linearized equation representing the dependence of Tg on the content of iso-, syndic- and heterotriads can only be used for the PMMA with the same type of stereodiads distribution.The theoretical relationship proposed in our previous papei; was applied to analyse the data of Tg and unperturbed dimension for PMMAs having various tacticities. The temperature coefficients,dlnσ2/dT,calculated by this method show a good agreement with the experimental ones.
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发布时间：2021-03-19 - 摘要：From X-ray diffraction patterns of uniaxially oriented fibers, the crystal structure of Nylon-1010 was determined. The Nylon-1010 crystallizes in the triclinic system, with lattice dimensions: a = 4.9A, b = 5Ak, c = 27.8A, α = 49°, β = 77°, γ= 63.5°, the unit cell contains one monomeric unit and the space group is PI. The degree of crystallinity of polymer was determined as about 60%, using Ruland's method.SAXS has been used to investigate the crystalline lamellar thickness, long periods, transition zones,the specific inner surface andan electron density difference between the crystal-line and amorphous regions for Nylon-1010,the analysis of data was based upon the one-dim-ensional electrondensity correlation function (EDCF).
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发布时间：2021-03-19 - 摘要：Poly(N-methyl aniline) (PMAn) can be doped and dedoped reversiblly by the treatment of protonic acid and base. The conductivity, which depends on the doping level, increases seven orders of magnitude after doping, but can not reach as high as that of the as-made doped PMAn. The doping process, in nature, is only the protonation of the polymer chain and independent of the counter ions. The doping levels are related to the equilibrium pH values. FTIR, UV-Visible and ESR spectra were employed to study the doping process and the structure of doped PMAn. The results revea that the chain structure cahanges with doping,and a lot of delocalized unpaired electrons exist in the doped PMAn,which favour the conductivity It seems that the free carrier of the electric conduction of PMAn is the delocalized cationic free radicals.
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发布时间：2021-03-19 - 摘要：The fine structures of ionic domains in the fluorine-containing copper (II) ionomers were examined by the Extended X-ray Absorption Fine-Structure (EXAFS) and Electron Spin Resonance (ESR). The results indicate that there are two basic coordination structure units in the ionomers. The first is a square planar coordination structure of Cu2+ ion with oxygen atoms which come from two carboxylate groups. The coordination number of Cu2+ is four and the bond distance of Cu2+-O is about 1.96A. The second is a binuclear coordination structure of Cu2+-Cu2+ ionc pairs with eight oxygen atoms which come from four carboxylate groups. In this structure,the coordination number of lst coordination shell is four and the bond distance fo Cu2+-O is about 1.96A. The 2nd shell is coordination of Cu2+-Cu2+ and the bond dis-tance of Cu2+-Cu2+ is about 2.64A.
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发布时间：2021-03-19 - 摘要：The radiation effect on poly (methyl methacrylate) with different tacticities was studied. It was proposed that chain scission process was in a kinetic equilibrium between scission and recombination. The dependence of chain scission and racemization on temperature results from molecular motion, "cage effect" and steric hindrance during recombination. G-value of chain scission increases with irradiation temperature. For isotactic PMMA, it is greater than that for atactic one.For isotactic PMMA, radiation induces not only chain scission but also racemization. Iso-tactic diad decreases with the increase of radiation dose. Meanwhile,atactic and syndiotactic diad increases.
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发布时间：2021-03-19 - 摘要：The pair poly (vinyl alcohol) (PVAI) and poly (vinyl pyrrolidone) (PVP) was shown to form completely miscible blends based on following experimental results. A single glass transition temperature was observed by DSC and optically clear films were obtained by casting solutions with DMSO as common solvent. Long spacings of PVAI increased with increasing of the content of PVP rapidly and thickness of lamellae of PVAI was changed slightly as derived from SAXS- It could be explained that two amorphous phases of PVAl and PVP were miscible nad sandwich among lamellae of PVAl. Comparing with plain PVAl and PVP infra-red absorption bands of hydroxyl group (OH) of PVAl and carbonyl group (CO) of PVP in blends shifted towards low vibrating frequency. It suggested that hydrogen bonds were formed between PVAl and PVP. Flory-Huggins interaction parameters calculated based on equili-brium melting points was -0.88.
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发布时间：2021-03-19 - 摘要：The structures of poly (vinyl alcohol) (PVA)/Poly (vinyl pyrrolidone) (PVP) blends with different compositions prepared by solution casting method were investigated by Small Angle X-Ray scattering (SAXS). Results indicated that the structural parameters of the blends were deeply dependent on both compositions and crystallization conditions. According to one dimension electron density correlation function proposed by Vonk and the concept of pseudo two-phase strutural model, we obtained that the long periods and the thichnesses of transition layer increased with increasing the content of PVP in PVA/PVP blends while crystallinity,thicknes-ses of crystal lamellae of PVA/PVP blends and spcific inner surface decreased. Annealing process made the crystallinity strengthen obviously. The densty difference of crystalline and amorphous regions were about 0.005g/cm3 at all the ratios of compositions.
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发布时间：2021-03-19 - 摘要：A series of the main chain liquid crystal polymers with X-shaped mesogens were synthesi-ed by low temperature solution polycondensation. All polymer samples had obvious thermotropic properties. Both flexible spacers and substituents had influence on the liquid-crystalline behaviour of the polymers The polymers were characterized by IR spectrometer, H-NMR spectro-scopy, DSC, polarizing microscopy and X-ray diffractometre.
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发布时间：2021-03-19 - 摘要：I. Steady-State FlowIn this paper, we accepted the multirod-rod molecular model and used Galerkin's method to calculate the rheological properties of dilute solutions under steady-state shear flow, uniaxial elongational flow and planar elongational flow as well as the complex flow combined shear with uniaxial elongational flow. It is showed that the model is hoped to become a more perfect molecular model describing the rheological properties of dilute solutions. The study in the paper not only enable one to carry out the numerical simulation of complex flow of viscoelastical fluid in terms of molecular models instead of the constitutive equations of continu-um mechanics,but also provides a new method for studyng the molecular model of concent-rated solution of polymer.
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发布时间：2021-03-19 - 摘要：In this paper, we continue to discuss the rheological properties of suspension of multi-rod rod model in unsteady flow and calculate the material functions after inc-eption of steady shear．The results revealed that the curves of material functions monotonicallv approached their steady-state values when the Weissenberg number was relatively small，and the expected overshoot of the curves of material functions wo-uld appear when we was large enough，and that the transent phenomena of matreial functions almost totally disappeared after τ—t／λ(1)N≥5．The results of multi-bead and rigid dumbbell models without the hydrodynamic interaction can be derived from this model with ease All above mentioned indicate that the model is most sophisticated one of describing the dilute solutions of rigid rodlike polymer．In the paper，we made a detailed analysis for the case of We=0.7 and a comparison betw-een approimate solutions of various orders． When We<0.7，we can adopt the sec-ond order approximate solution instead of the high order numerical solution to minimize the calculation and without the risk of producing a untolerable error．
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发布时间：2021-03-19 - 摘要：In the paper, we took the xanthan gum, which is widely used in the oil-recovery industry as the"fracturing fluid", as an example and analysed the mechanism of its gelling. Introducing the adsorption reaction and thixotropic function f (t) into the molecular network model and assuming the contribution of the broken pieces of network, the free and stray chains to the toatl stress tensor to be Newtonian, we obtained a constitutive equation on the basis of the carreau-Bird model. The, parameters in the constitutive equation were estimated and optimized according to the experiments data of the linear viscoelasticity and non-linear material functions of the xanthan gum by using the tolerable multi-surface-body gradient method with constrain-ed conditions. This model can predict the rheological properties which are in agreement with those of the xanthan gum. It is obviously found that the shear viscisity and complex one of the xanthan gum do not obey the Cox-Merz rule in the range of shear rates of these experiments.
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发布时间：2021-03-19 - 摘要：Two kinds of commercial 12 μ PET filma, e.g. equilibrium-film and tensile-film, were investigated by FRS-XRSA suggested by suthor, Pole-Figure method and SAXS. Many important informations and parameters of the crystallinity, texture and superstructure of the films are obtained, for example, crystailrnity, crystailite size, orientation distribution, orientation factors, long periodicity, crystal-region dimension, amorohous-region dimension and electron-de-nity radial distribution function etc. These structural informations not only are the records of manifacture processes,but also have important meaning ofr understanding various properties of the films,e.g. mechanical,optical,thermical and surface properties etc. These two kinds of PET films belong to (TM,100) uniplanar,c-exis M.T. biaxially orfented equilibrium film or nin-equilibrium film.
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发布时间：2021-03-19 - 摘要：Mode Ⅰ and Ⅱ delamination of continuous carbon fiber reinforced poly (phenylene ether ketone) were studied by using, respectively, double cantilever beam (DCB) specimens and end notched flexure (ENF) specimens. Mode I fracture criteria based on the linear elastic theory, GIC,and that on the elastic-plastic theory, JIC, were 0.69 and 0.63 kJ/m2, respectively. Both G/c and JIC was independent of the crack length. Stability of Mode Ⅱ delamioation depended on the ratio of crack length to half span α/L. Unstable Mode II delaminaion occured at a/L less than 0.7 and the critical energy release rate for it was 1.62kJ/m2. The critical energy release-rate for stable Mode II delamination depended on determination of the critical lwas at which crack started to grow and ranged from 1.74to 2.74kJ/m2.
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发布时间：2021-03-19 - 摘要：The gelatinous and macroporous polyethylene glycolpolystyrene graft copolymer (PEG-Resin) were synthesized by mean of ring opening polymerization of ethylene oxide on hydro-xyethyl resin. The kinetic behavior for coupling of Boc-Gly-ONP with glycine anchored to PEG-Resin, chloromethylated resin and glycine acetate in solution were determined. The experimental results showed that reaction on PEG-Resin support proceeded three times faster than that on chlorotrtethylated resin and as fast as that reaction in solution The kinetic character of gelationus PEG-Resin was influenced by the degree of crosslinking of the copoly-mer.
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发布时间：2021-03-19 - 摘要：Laser Desorption/Fourier Transform Mass Spectrometry (LD/FTMS) is a new effective method for determination of the average molecular weight and the distribution of oligomers (MW = 1000-10000). By using this technology, we have studied a series of homopolyethers and copolyethers and have got distributional figures of dominant pseudomolecular ions attached K+. The number-average molecular weights obtained by self-compiling program dealing with data of the figures are in good agreement with that of VPO, GPC, NMR,etc. We have dis-cussed the problems that alkalimetal salts in sampling and some experimental parameters have influenced on the results obtained.
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发布时间：2021-03-19
Research Article
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