最新刊期
卷 ， 期 3 ， 1983
- 摘要：The influenee of two different feeding ways of a two-step method of segmented polyether urethane (SPEU) solution polymerization on morphology of SPEU was inve-stigated in electron microscope．SPEU prepared by [PTMEG—MDT]-Extender reac-tion feeding way consists of two phases and the dispersion domains which are mainly made up of hard segments are small stick·shaped in morphology；electron diffraction pattern indicates that the domain is crystalline．SPEU prepared by [PTMEG—MDI]—Extender reaction feeding way also showed two-phase structure：The domains are-spherical in shape，and they are amorphous．
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发布时间：2021-03-19 - 摘要：Narrow-distribution polystyrene was eluted on a NDG (silanized rigid SO2) column with benzene, toluene, THF and MEK as the eluants. For solvents (benzene and toluene) with low polarity, the hydrodynamic volume M[η] and the modified hydro-dynamic volume M[η]/f(∈) are valid as the universal parameter for GPC. But for polar solvents (THF and MEK), they are attracted to the surface of packing by electrostatic force remained on it to form a restrictive layer. This causes the reduction of the dimension of the pores of the packing and displacement of polts of M[n]-Ve and olg M[n]/(e)-Ve to a lower Ve values.
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发布时间：2021-03-19 - 摘要：The copolymerization of VDF-TFE was carried out in aqueous medium containing a fluorosurfactant and with diisopropylperoxydicarbonate (IPP) as initiator and acetone as chain transfer agent. A series of VDF-TBE copolymers of different compositions and different molecular weight ranges have been prepared.The VDF-TFE copolymer shows good mechanical properties and thermal stability. The pyroelectric coefficient of the copolymer attained a maximum value which corresponds to the minimum melting point of the copolymer,at about 20mol% TFE content.
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发布时间：2021-03-19 - 摘要：The "living" sequential block copolymerization of e-caprolactone (CL) and DL-lactide(LA) by bimetallic u-oxobutoxide has been investigated and the well defined AB type block copolymers with narrow molecular weight distribution (Mw/Mn 1.1) and microphase separation motphology were synthesized In vitro, the complete degradation time of the block copolymer films in deionized water at 50℃ ranging from several months to 3 years depending on the molar ratio of CL/LA, in it. In vitro the matrix release rate of norgestrel varies with the ration of CL/LA.
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发布时间：2021-03-19 - 摘要：The adsorption of sodium polystyrene sulfonate (PSSNa) on kaolin from aqueous NaCl solutions of various concentrations at 30℃．45℃ and 60℃ has been studied．In the absence of NaCl，the amount of adsorption was found to be independent of tempera-ture. i.e．heat of adsorption，△H=O．The shape of adsorption isothel m indicates the presence of multilayer adsorption and sonic correlation between the isotherm and the nsp／C～C curve of PSSNa solution has been found．In aqueous NaCl solution，heat of adsorption is still equal to zero，but the amount of adsorption increases considerably，and the isotherm does not show multilayer adsorption．The crystalline indices of kaolin was found unchanged after the adsorption of PSSNa．It is supposed that the adsorption of PSSNa on kaolin is physical in nature．The multilayer adsorption and the increase of adsorption by NaCl may be attributed to the presence of phenyl groups in the side chain of PSSNa and the coiling of polyanion PSS-．The mechanism of adsorption has been discussed．
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发布时间：2021-03-19 - 摘要：The photopolymerization of aerylamide (AM) initiated with N, N-dimethyltoluidine (DMT) has been studied. The kinetic results show the rate of polymerization in the form ofRp∝[DMT]0.35[AM]1.34(in H2O) Rp∝[DMT]0.33[AM]1.32(in DMSO)and the apparent energy of activation of photopolymerization Ea to be 4.62 Kcal/mol. Some tentativemechanism of this photopolymerization has been proposed.
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发布时间：2021-03-19 - 摘要：The thermal and mechanical properties，microscopic morphology and crosslinking density of bisphenol A modified epoxy resin and CTBN toughened epoxy resin have been examined．Four different curing agents，namely，piperidine，triethanol amine，70# anhydride and boron trifluoride．ethylamine complex have been used．The tremendous influence on the toughening effect by the added bisphenol A was only obtained when the basic catalytic curing agents such as piperidine and triethanol amine were used．The rise in the impact toughness of the cured material is ascribed to the decreased crosslinking density of the epoxy resin network．The rise of the fracture toughness is the synegistie effect of the ineressed volume percent of the rubber phase and the dec-teased erosslinking density of the matrix．CTBN is abbreviated from earboxyl terminated butadieneacrylOnitrile rubber．70# anhydride is a eutectic mixture of four tetrahydrophthalic anhydride isomers．
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发布时间：2021-03-19 - 摘要：PU(HTBN)／PMMA interpenetrating polymer networks (IPN’S) were synthesized by simultaneous polymerization，and were investigated by dynamic mechanical spectros-copy and transmission electron microscopy．Theoretical caleulation by Davie’s equation and experimental results showed that there are two continuous phases Which separate from each other，and two glass transition temperatures (Tg1，Tgl)corresponding to the components in the polymer networks．Owing to the“forced compatibility”produced by interpenetration．the phase domains are much finer in full．IPN’s (1000—2000 A) than in grafts (3000一6000 A) and semi-IPN，s(about 3000 A)，and become more smaller and uniform with the increase of phase continuity by appropriate crosslinkage．The reaction between some HTBN molecules and MMA bring about the increase of Tg1
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发布时间：2021-03-19 - 摘要：By increasing the amount of nitrile group or adding chain extension agents or com-onomers properly, some semicompatible IPN's were obtained. Their morphology and glass transition behavior were investigated by dynamic mechanical spectroscopy and transmission electron microscopy. The phase domain sizes are about 200 A, and Tan σ values remain about 0.2-0.3 within -20℃-130℃ temperature range for PU(HTBN)/ PMMA IPN's with 24.3% acrylonitrile. Due to the strong interaction of polar groups in the PU(PCE)/PMMA IPN's, the phase domains become finer and only a single glass transition is obsered.
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发布时间：2021-03-19 - 摘要：The anionic emulsion polymerization of octamethylcyclo-tetrasiloxane (D4) has been studied in the presence of dodecylbenzensulfonic acid (DBSA) and its sodium salt. (Na-DBSA) The effects of temperature and amounts of emulsifeir and catylyst on the reaction-rate and M.W. of the polymer were discussed. It is assumed that the anionic emulsion polymerization contains three kinds of elementary reaction: the opening reaction of D4, the addition reaction of D4 to HO-ended siloxane and the condensation reaction between HO-ended siloxane and that the surface of emulsion particles in the main site of the reaction.
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发布时间：2021-03-19 - 摘要：The microstructure and monomer sequence distribution of polypentadiene-1，3 obta-ined with naphthenate neodymium catalyst have been examined by IR．1H and 13C-NMR spectroscopy．The results show that 1，3-pentadiene enters in polymer chain predomin nantly as cis-1，4 unit (70％ mole) and trans．1，2(25％mole) with minor fraction of trans-1，4 units (5％mole)．Based on our new set of empirical parameters for calculat-ing chemical shifts，the assignment of carbons in the aliphatic region of 13C-NMR spe-ctra has been given．Thus cis-1，4，trans-1，4 and trans-1，2 units-and sequences of monomers can be identified by 13C-NMR spectroscopy．It is found that monomer units of the polypentadiene-1．3 exist only in head-to-tail structure without any head-to-head or tail-to-tail structure．Sequence of 1，4．1，2 has been also observed．In addition．we have measured the spin lattice relaxation times(T1) for carbons of cis-1，4 units．
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发布时间：2021-03-19
Research Article
- 摘要：The DSC curve of melting and crystallization of high pressure polyethylene was simulated with divided difference interpolation by means of the algebraic polynomial Pn (X) = f(x0) + f(x0,x1)(x-x0) + f(x0,x1, x2) (x-x0) (x-x1+…+ f(x0, X1,…xn) X (x-x0)(x-X1)…(x-xn-1). For the convenience of calculation, the above polynomial was changed into following formula Pn (x) = [{[f(x0…xn) (x-xn-1) +f(x0…x0-1)](x - xn-2) +…+f(x0,x1,x2)} × (x-x1) + f(x0,x1)] (x-X0)+f(x0)(Ⅰ)A programm was written using both (Ⅰ) and Simpson formula. The coordinate of the sum of points and the peak areae of DSC curve had been calculated by microcom-puter. Comparison with “to count mm-check”and “cut and weigh”methods gives good agreement. It shows that the above method is convenient and applicadle.
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发布时间：2021-03-19 - 摘要：The scanning electron microscopic examination of α and β i-polypropylene was carried out after the samples were subjected to electron beam bombardment in the instrument for 1 to 2 minutes. This technique gives pictures of α and β-spherulite of i-polypropylene with better depth of field, especially when the samples are prepared in the presence of paraffin oil.
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发布时间：2021-03-19 - 摘要：The ratio of the zero shear viscosity of PP to its viscosity corresponding to the melt index at same temperature as a new parameter characterizing molecular weight distribution was suggested. The experimental results manifest itself a good regularity between this parameter and molecular weight distribution.
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发布时间：2021-03-19 - 摘要：The relationship between the value of n in the Nd(OPr1)s-nCln and the reactivity ratio (γ) of dienes was studied through the copolymerization of butadiene-isoprene with the binary catalyst system, Nd (OPri)3-nCln-AlEt3. The results indicate that the monomer (isoprene) which has higher electron density on its conjugated double bond is more reactive, as a result, both its content in copolymer and its reactivity ratio (γ) are increased with the increase of the value of n.
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发布时间：2021-03-19
Research Bulletin
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