最新刊期
卷 ， 期 1 ， 1998
- 摘要：A new equation for correlating morphological parameters,particle size ( d ),particle size distribution ( σ ),particle volume fraction (φ) and matrix ligament thickness ( T ) is derived.The equation is generally applicable to binary polymer blends with the lg normal distribution of particle size and the morphology of well dispersed particles.The effect of σ on T is discussed.The new equation predicts that T increases with d and σ ,and with reducingφ.The effect of σ is found to be influenced by φ.The higher theφ,the more significant the effect of σon T.The new equation is applied to the poly (vinyl chloride)/nitrile rubber,polypropylene(PP)/EPDM,and PP/EVA blends.The theoretical predicitions agree well with the experimental results.
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发布时间：2021-03-19 - 摘要：The phase behaviour of ternary blends polycarbonate (PC)/poly(styrene stat acrylonitrile) (PSAN)/poly (methyl methacrylate) (PMMA) was analyzed using F H meanfield theory.The miscibilities of the ternary blends were predicted by calculating the interaction parameters, χ blend ,from the corresponding binary segmental interaction parameters.It has been proved that PSAN within suitable composition range and molecular weight can act as an effective compatibilizer to improve the phase separation of PC/PMMA blend,and a miscible ternary blend is available accordingly.
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发布时间：2021-03-19 - 摘要：Based on a simplification of physical model, the change of conductivity was studied by using the ratio of real current to theoretical current during the stretching of conductive rubber, and the relevant measurement was set up. The composite of polyaniline (PAn) and SBS was prepared by in situ emulsion polymerization technique, which can be processed by melt method (MP) or solution method(SP). The SSP sample was made by the treatment of SP sample with m cresol. The change of conductivity was measured during the stretching of the composites,of which the PAn content is 11. 0%(wt).The results show that;(A) the conducyivity of MP sample markedly increased with elongation,for example,the conductivity increased about 15.6 times at the elongation(k) of 450%;(B) the conductivity of SP sample increased to 5.2 times at k equal to 500%;(C) For SSP sample the change of conductivity was relatively small ,1k/σo)k/σo=1+k/(a+bk2) was suggested to express the regularity.The result may be caused by a tenuous interconnected network of conductive component which was induced by secondant doping with m-cresol.
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发布时间：2021-03-19 - 摘要：Poly(N-isopropylacrylamide) (PNIPAAM) was synthesized by free radical polymerization.By means of Ubbelodhe viscosimeter,the temperature dependence of viscosity of PNIPAAM THF and PNIPAAM H2O systems was tested.The relative viscosity of PNIPAAM THF system was found linear increased with temperature increased,the higher the temperature was,the larger the viscosity deviated from Einstein's theory for viscosity of suspension,the dispersed substance was found tended to linear structure in high temperature.But the relative viscosity of PNIPAAM-H2O system was found inereased slow with temperature increased and the transformation points were found,the higher the temperature was,the little the viscosity deviated from the Einstein's theory,the dispersed substance was found tended to globular structure in high temperature.The intrinsic viscosity of PNIPAAMTHE system was found increased with temperature increased,but the intrinsic viscosity curve of PNIPAAM-H2O system was quite complex,and the step declining curve was found.But the viscosity curve of PNIPAAM-H2O system was quite complex.The intrinsic viscosity determined by experiment was also used to characterize the molecular weight of PNIPAAMMn=8.44×105g·mol-1.
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发布时间：2021-03-19 - 摘要：The samples of maleic anhydride graft polyproylene conposing different quantity of maleic anhydride are prepared.The kinetics of isothermal crystallization has been investigated by DSC.The physical and chemical mechanism by which succinic anhydride group reduces the surface free energy of radial growth of PP spherulite,increases the crystallization rate,but reduces the crystallinity was demonstrated.The influence of succinic anhydride group on mechanism of spherulite growth and nucleation was discussed.
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发布时间：2021-03-19 - 摘要：A model for the pseudonetwork morphology is established to further study the influence of morphology on the toughness of polymer blends.The particle dispersion factor ( ξ ) is defined,where 0< ξ 1.For the particle dispersions of cubic lattice,well dispersed particles and pseudonetwork,the values of ξ are equal to,close to and smaller than one,respectively.A new equation for calculating the matrix ligament thickness of polymer blends with the pseudonetwork morphology is derived.The effects of other morphological parameters on the matrix ligament thickness are analyzed.The calculated vaiations indicate that the matrix ligament thickness reduces with the reductions of particle size,size distribution and particle dispersion factor and with the increase of particle volume fraction,respectively.It is demonstrated that the matrix ligament thickness of polymer blends with the pseudonetwork morphology is smaller than that with the morphology of well-dispersed particles when other morphological parameters of particle are identical.
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发布时间：2021-03-19 - 摘要：The aqueous solution of Poly(N isopropylacrylamide) (PNIPA) exhibits a lower critical solution temperature(LCST,32℃).Its hydrogel undergoes phase separation as the temperature is raised above LCST.This temperature sensitive hydrogel has been widely used in many fields,for instance,controlled drug release,enzyme immobilization and release of solutes.However,response to pH of hydrogel may be required at the same time for some applications.Here, a new intelligent hydrogel which can respond to temperature and/or pH changes is described.The new hydrogel was prepared by using interpenetrating polymer network(IPN) technique.Poly(acrylic acid)/Poly(N-isopropylacrylamide)(PAAc/PNIPA)IPN hydrogel was synthesized.The temperature and pH sensitivity of this hydrogel was studied.The Swelling Ratio(SR) of this hydrogel in weak alkaline solution is much greater than that in acidic solution.Experimental results revealed that its SR rises as the temperature is raised in acidic solution.On the other hand,in weak alkaline solution,when the temperature is below the LCST of PNIPA(32℃), the SR of the hydrogel also rises as the temperature is raised.However,when he temperature reachs the LCST or higher,its SR slumps suddenly and drops quickly.This IPN hydrogel may be useful in the field of controlled durg delivery.
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发布时间：2021-03-19 - 摘要：The adsorption capacity and the reducing power of acidic cellulose based magnetic polyamidoxime adsorbents(AMAO) for bromine in adsorbing cycles were measured.The initial adsorption velocity of original adsorbent and its reduction proportion of adsorbed bromine were found to be twofold or more than that of the recovered AMAO.However,data obtained from the first reactivating adsorbent are almost the same as the second one.Possibly,the structure of the original adsorbent has changed thoroughly after adsorption. The slight variation of adsorption capacity and the rapid decrease of reduction proportion of bromine in cycling adsorption suggest that AMAO is an adsorbent for bromine uptake with an important practical value.
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发布时间：2021-03-19 - 摘要：The solvated metal atom impregnation (SMAI) method was employed to prepare four resin immobolized Pd Cu bimetalic catalysts of different specific area.The results of XRD and TEM showed that as the specific area of the resin increased,the Pd and Cu particle size of the catalysts with the same metal content decreased,so the catalytical activities of the catalysts in hydrogenation of toluene and diacetone alcohol as well as in reduction of oxygen on the fuel cell electrode increased.
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发布时间：2021-03-19 - 摘要：Liquid crystal polymer segments with hydroxyl end group PET/60PHB were synthesized by in situ acetylation method in which the PET oligomer,p hydroxy benzoic acid and a little amount of EG were used.Then the liquid crystalline block copolymers PET/60PHB b PC were prepared by using LCP segment PET/60PHB obtained as a macromonomer and ester exchange synthetic technology of PC.The liquid crystalline block copolymers were also characterized by the aids of determination of inherent viscosity,DSC,polarizing microscope,X-ray diffraction and FTIR etc..It is found that when the inherent viscosity of PET oligomer is 0.05～0.07dL/g,Ac2O/PHB(mol/mol)=1.3,EG/PET(mol/mol)=0.06, the hydroxyl terminated LCPs PET /60PHB with light colour,good solubility and liquid crystalline properties can be obtained.The liquid crystalline block copolymers with high inherent viscosity and good liquid crystalline properties can be synthesized with above LCPs as a raw material through melt copolycondensation.It is indicated that the liquid crystalline block copolymers are nermatic,but the texture of liquid crystalline state of the block copolymer is quite different from either the pure LCPs PET/60PHB or the mixture of PET/60PHB and PC.Furthermore,the analysis methof of end group of LCP PE/60HB is also established.
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发布时间：2021-03-19 - 摘要：Effects of physical aging on the structure,mechanical and other properties of atactic polystyrene (a PS) films and fibers are studied by modulated differential scanning calorimetry(MDSC),density,solvent diffusing rate,stress strain behavior and sonic velocity measurements,and the corresponding observations are tentatively explained from the viewpoint of cohesional entanglements.It is shown that the glass transition temperature (Tg),relaxation enthalpy ( ΔH ) and its peak value (Tmax ) in the MDSC curves,as well as the initial modulus(E),yield strength(σy)and strength at break(σb) all rise with the increase of physical aging time.On the other hand,the solvent diffusing rate slows down after being annealed below is Tg,while the sonic wvlocity and density nearly keep unchanged.The weak interaction(i.e.cohesional entanglements) introduced by the physical aging is similar to van der Waals'force from its physical characteristic.All experimental results are interpreted by the assumption that the number of cohesional entanglements increase during physical aging.
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发布时间：2021-03-19 - 摘要：Perphemnazinum(PERP) with tertiary amino group and benzoyl peroxide (BPO) initiation system,which can be applied in preparing the drug release membrane containing PERP,was studied.The rate of polymerization of methyl methacrylate (MMA) initiated by PERP BPO system was determined,respectively.It was found that the presence of PERP could increase the rate of polymerization and shorten the induction peroid of polymerization.The order of activity of the amines in DMT(N,N dimethyl toluidine)>DMA(N,N-dimethyl aniline)>PERP.The rate equation of MMA polymerization initiated by PERP-BPO was agreed well with the equation of polymerization with redox initiation system.The value of activation energy overall by PERP-BPO was obtained to Ea=41.8kJ/mol which is lower than that of BPO initiated.From the results of the end-group analysis and molecular weight determination,it is proved.That the PEP as an end-group of PMMA.Accordingly,the initiation step includes the addition of PERP radical to monomer and forms the end-group of polymerization.We also have done the relationship between temp exothemicity and time in the course of the polymerization initiated by PERP-BPO sys tem.Based on this result,it is confirm of that the initiation mechanism of PERP-BPO system is similar to that of redox system by DMT-BPO system.The release behavior of PERP from the drug membranes was parsued.It showed that the release of PERP could last at least 20 days.
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发布时间：2021-03-19 - 摘要：A detailed study of the microstructure of methyl methacrylate (MMA) and butyl acrylate (BA) copolymer prepared by group transfer polymerization (GTP) was carried out by using 13 C NMR spectroscopy. Methyl methacrylate and butyl acrylate centred triad molar fraction were determined from the quaternary carbon and carbonyl group resonance signale. The experimental sequence concentrations were in agreement with the values calculated from the terminal copolymerization model and bernoullian statistics. A greater block tendency of BA monomers may be noticed in both experimental and calculated distribution,which is due to the large difference between the reactivity ratios of MMA and BA in group transfer copolymerization.
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发布时间：2021-03-19 - 摘要：The tests including steady stress sweep and dynamic frequency sweep were performed to characterize the rheological behavior of phase inversion evolution at high concentration of the emulsifier (e.g.10.9%). It is shown that the phase inversion is complete, which means that all water molecules in the system are transformed to be continuous phase at the phase inversion point. The viscosity of the system before the phase inversion point is almost constant independent on stress, which is the characteristics of Newtonian fluid.The systems after the phase inversion point exhibit high viscoelasticity and strong pseudoplasticity at relatively high stress.This is attributed to the formation of a new static structure among waterborne particles through hydrogen bond between the emulsifier and water molecules,and the static structure is broken at high stress.
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发布时间：2021-03-19 - 摘要：Atactic polypropene was synthsised with homogeneous catalytic systems of varios titanium compounds activated by methylaluminoxane(MAO).The titanium ligands affect both catalytic activity and stereoregularity of polypropene obtained.For novel η 5 cyclopentadienyltri n propyloxy titanium CpTi(O n Pr) 3 /MAO catalytic system,the influencing factors of polymerization temperature,Al/Ti molar ratio and propene pressure on propene polymerization have been studied.The catalytic activity at polymerization temperature 40℃ and Al/Ti molar ratio 200 was 220kgPP/molTi-h.The kinetics of early state propene polymerization with CpTi(O-n-Pr)3/MAO has been inverstigated.The polymer yield increases almost linearly with increasing the titamium or monomer concentration.The apparent rate of polymerization (Rp)versus titanium and monomer concentration appears the first order reaction rule,and the apparent rate constant(Kp)is 2.92×105mol·L-1·h-1 at 40℃.The calculated polymerization activation energy (△E)is 7.88×103J·mol-1,while the impact fractor(A) is 1.41×104mol·L-1·h-1. After boiling heptane extraction of the polypropene for 8h.The soluble fraction with more than 95% by weight was isolated and characterized as atactic polypropene by 13CNMR,WAXD and FTIR.The molecular weight (Mw)and its distribution (Mw/Mn) determined by GPC were 8.0～10.0×104 and 2.0 respectively.
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发布时间：2021-03-19 - 摘要：A new kind macroinitiator PS ACPC has been synthesized via two steps reaction, i. e. anionic polymerization of styrene, followed by end capping the resulting living polystyrene with 4,4' azobis(4 cyanopentanoyl chloride). The prepolymer PS ACPC containing azo group with molecular weight 3000 to 19000 can be used as a macroinitiator for block copolymerization. When it was mixed with methacrylic acid (MAA) or β hydroxypropyl methacrylate(HPMA) in benzene or tetrahydrofuran solvent at 75℃. The decomposition of azo group on PS-ACPC took palce and the PS radical would initiate the second monomer block copolymerization.The resulting block copolymers were characterized by solubility property,GPC,IR,NMR and DCA analysis.It was found that the molecular weights of bdockcopolymers,i.e.PS-b-PMAA,PS-b-PHPMA,are higher than that of prepolymer,respectively,and the descending order of contact angle is PS>PS-b-PHPMA>PS-b-PMAA.
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发布时间：2021-03-19
Research Article
- 摘要：The polymerization of methyl methacrylate using Nd(O i Pr)3 Al( i Bu)3 coordination catalyst system has been investigated. The effects of various alkyl aluminiums, the aging temperature of catalyst, the additive of DMSO and polymerization temperature were studied in detail. It has been found that the highest conversion polymerization was obtained with Al(i Bu)3 as cocatalyst. Lower aging temperature of catalyst was favoured incresse of both polymerization conversion and molecular weight of PMMA.1H-NMR spectrum of PMMA formed indicated that the most stereostructure of PMMA is syndiotactic.Kinetic study showed that the rate of polymerization is first order with respect to monomer and catalyst concentration.The activation energy of polymerization is 43.5KJ/mol.
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发布时间：2021-03-19 - 摘要：Several calix n titanium compounds( n =4,6,8) have been synthesized and used for ethylene and styrene polymerization.Results show that ethylene was polymerized by calix n titanium /MAO systems with mild activity and very high molecular weight,and styrene was polymerized with high activity and syndiotacticity.In the case of calix 4 titanium and calix 6 titanium,the polystyrene obtained had syndiotacticity more than 90%.No syndiotactic polymer but only atactic polystyrene was obtained by calix [8] titanium compound.
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发布时间：2021-03-19 - 摘要：In ammonia pyrolytic process of polysilazines via reactions of hydrazine with MeHSiCl2 (or Me(CH2CH)SiCl2) followed by crosslinking treatment to obtain PHSZ and PVSZ respectively,was traced by combining TG GC,IR,XRD,elemental analysis,and density measurement.Below 673K N—N breakage and transamination occurred in PHSZ and PVSZ,yielding Si—NH2 containing end groups and N2H4 release,while Si—H bonds in PHSZ were nucleophilic substituted to form Si—NH2 and release H 2.At higher temperatures Si—C,C-C,C-H,N-H breakages occurred simultaneously to form radicals (≡Si·,≡C·,·NH2),followed by radicals'transference and combination to remove alkyl or alkeneyl groups via releasing H2.CH4,C2H4,C2H6,etc.,thus leading to inorganic structures with negligible carbon content above 873K.The amorphous pyrolyzates were obtained when heat treatment temperatures were lower than 1673K,and microcrystalline Si3N4 at 1873K.
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发布时间：2021-03-19 - 摘要：Polypropylene(PP) and polyamide 6(PA6) in situ fibrillation blend was compatibilized with PP g MAH.PP,PA6 and PP g MAH were blended in a single screw melt extruder with different blending procedure.When there was no compatibilzer PA6 could fibrillated in PP easily.However,in the existence of compatibilzer the interaction between PA6 and PP would change with the different procedure for adding the compatibilzer:PA6 would be the spherical particles when the compatibility was good between PP and PA6,or PA6 could form fibrils in PP.If PA6 was fibrils the blend's impact strength was improved while the tensile strength decreased.
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发布时间：2021-03-19 - 摘要：Phase separation during curing reaction in a ternary mixture of Novolac, Poly(ethylene co vinyl acetate) (EVA) and Hexamethylenetetramine (Hexa,curing agent) was investigated by time resolved light scattering.Novolac/EVA system exhibited a Low critical Solution Temperature (LCST) type phase behavior due to H bonding interaction between components.In the early stage of curing,the mixture was in single phase.As the curing reaction proceeded,phase separation took place via spinodal decomposition (SD) induced by the increase in the molecular weight of Novolac.The time variation of qm,the characteristic wavenumber of phase separated structure st which the maximum intensity is located,is quite different from iso-quench thermally-induced SD.q is increased slightly with time attributed to the rapid curing reaction and eventually levelled off with gelling.Cocontinuous phase separated structure was ultimately formed during curing reaction.
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发布时间：2021-03-19 - 摘要：Micron size Monodispersed polymethyl methacrylate (PMMA) and polystyrene (PSt) latices were synthesized by emulsifier free emulsion polymerization in single step. By suitable variation of the ionic strength, the monomer concentration, or the initiator concentration in the aqueous phase, the final particle sizes of PMMA and PSt ranged from 0 6μm to 1 8μm,and from 0 8μm to 2 2μm, respectively, with the distribution coefficient of particle size below 5%.(The mean diameter of latex particles increased with increasing the ionic strength and mononer concentration.On the contrary,it decreased as the initiator concentration increased for PMMA system.Therefore,a combination of low initiator,high ionic strength and hight monomer concentration is expected to result in larger size particles and narrower size distribution than ordinary emulsion polymerization.) The effects of the ionic strength and the monomer concentration in the emulsifier-free emulsion polymerization on the particle size are slight but significant for PMMA system versus PSt system under the same conditions.This is explained by the different nucleation mechanism of emulsifier-free emulsion polymerization of MMA and St.
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发布时间：2021-03-19
Research Bulletin
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