最新刊期
卷 ， 期 4 ， 1999
- 摘要：Dynamic behavior and phase separation sensitive to temperature of a series of polyacrylic gels were studied by dynamic light scattering. The dynamic behavior of the gels is characterized in terms of the correlation length ξ and diffusion coefficient D. The rules of the influence of cross-linking degree, concentration of polymer and amount of initiator on and D were obtained. When cross-linking degree increases, decreases and D increases, respectively, and there are different scaling relationships under lower or higher cross-linking degree. There is also a scaling relationship between the diffusion coefficient and the concentration of polymer. The higher the concentration, the larger the diffusion coefficient.When the amount of initiator increases,ξtends to be small. And the rules of the phase separation sensitive to temperature for the gels are as follows. When temperature increasesgradually the cooperation diffusion coefficient D increases, the mesh size ξdecreases, the distribution of ξtends to narrow. When temperature decreases gradually, the solvent gets poorer,so phase separation takes places for Х-induced microsyneresis, thus turbidity of the gel appears. Furthermore, the higher the degree of cross-linking, the higher the temperature of phase separation.
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发布时间：2021-03-19 - 摘要：A series of simultaneous interpenetrating polymer networks (SINs) composed of epoxy resin(epoxy) and urethane acrylate resin(UAR) with different molecular weights were synthesized and characterized. The polymerization kinetics of both network formations was monitored by using Fourier transform infrared spectroscopy(FTIR) for preparing the toughed epoxy or reinforced UAR materials. It was found that during the course of synthesis, the polymerization rate for formation of both networks is almost independent of the concentration of reactants especially at the early stage of reaction. The two pairs of reactants interfere with each other appreciably in the SIN systems, although they follow different polymerization mechanisms, i.e., step polymerization and free radical polymerization. All these unusual polymerizaion kinetics behaviors observed could be well correlated with the changes of viscosity and morphology of the systems. UAR network synthesized with difunctional polyoxypropylene polyol (PPO) having larger molecular weight (Mn=2000)shows a partial microphase separated morphology. Thus, the SIN consisting of epoxy and such a UAR not only exhibits a phase separated behavior between the two networks but also a microphase separation for UAR giving rise to even more depressed reaction rates for network formation. It is clear that for these SIN systems the polymerization kinetics is mainly controlled by diffusion effect. Furthermore, the sequence of both network formations has been adjusted by changing the amount of initiator for UAR.
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发布时间：2021-03-19 - 摘要：A series of polar resins based on polystyrene with carbonyl groups were synthesized and their polarity and skeleton structure were characterized. The relationship of polarity with the physical structure of the resins was investigated, and the adsorption capacity and the adsorptive selectivity properties of these resins toward stevioside and rebaudioside A were discussed in great detail. The results showed that polar resin with carbonyl group content at about 0.9～1.0 mmol/g, average pore radius at around 4.0 nm and specific surface area above 500m2/g exhibited the highest adsorptive selectivity toward stevioside.A new method for separating rebaudioside A from other stevia glycosides is also developed.
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发布时间：2021-03-19 - 摘要：Molecular dynamics simulations of model polyethylene chains were performed. The time evolutions of chain conformation for a range of molecular weights are studied.The process of chain relaxation and collapse includes many stages. Local clusters formed and were relatively stable for a long time, in addition, the local order structure still exists in the last compact coil. The results verified that the modification of force field for demonstration of stages in the folding process is not necessary. When the number of chain units is less than 1000 CH2 units, the local collapse stage is difficult to be observed, just as the results reported by Kavassalis et al..Nevertheless, as the chain became longer, the stage of collapse is clearly characterized by the average number of clusters. The following feature are found:first, the transition between different stages of chain folding became sharper as the chain becme olnger; second, the clusters inclused the local order structure became more stable as the chain became olnger. Based on our analysis, local collapse stages can be characterized by the number of clusters. The cluster structure was the essential feature of the local collapse,and such structure will be maintained in the following collapse structure. There is an interesting increase of the torsion energy for system during the coalescence of local clusters in the relatively long chains. The increase of the torsion energy may lead to the expansion of the radius of gyration.
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发布时间：2021-03-19 - 摘要：One-step reactive extrusion of PP/AS alloys was studied by using a twin-screw extruder at the presence of dicumyl peroxide (DCP). Compared with mechanical extrusion, reactive extrusion greatly reduced the dispersed particle size. It is due to the formation of graft copolymer, which behaves as in situ formed compatibilizer in the blends. In order to suppress the degradation of PP chains during the process, some coagents containing double-bond were added in combination with DCP. It was recognized that the coagent which has proper molecular weight and suitable double-bond content could lead to suppression of PP degradation, and promote the grafting reaction simoltaneously. It was found that the multifunctional monomer glycerol trilinoleate (GTL) is a suitble coagent in this case. By adding DCP and GTL at the proper contents, the morphology and mechanical properties of PP/AS alloys were greatly improved.
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发布时间：2021-03-19 - 摘要：Urease was doped into polypyrrole (PPy) film when pyrrole (Py) was polymerized by cyclic voltammogram. By Combination of PPy modified urease electrode and CO2 gas-sensitive electrode a bioelectrochemical sensor was formed, which responses to urea. Factors affecting the activity of urease in PPy film were studied and activation energy of the ferment was determined. It was found that electrode potential is in direct proportion to the logarithm of the concentration of urea within the concentration range of 5.0×10-5～1.0×10-2mol/L.
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发布时间：2021-03-19 - 摘要：By using dynamic stress rheometer-DSR-200, linear viscolelasticity of four polyethylene melts has been characterized by small amplitude oscillatory shear test. From data of storage moduli G′(w) and loss moduli G″(w), discrete relaxation spectra have been obtained for four polyethylene melts by means of linear regression method, regularization method and nonlinear regression method, respectively. Effects of the calculation methods, computing parameters, temperatures and materials on the spectrum have been discused. It was found that computing parameters-relaxation time numbers and relaxation time rangehave a strong effect on linear regression and regularization method, but less influence on nonlinear regression method. Three calculation methods can obtain nearly the same relaxation spectrum when choosing fewer relaxation time numbers, but quite different results when chossing more relaxation time numbers. Both temperature and materials have strong effects on discrete relaxation spectrum due to the structural charcteristic of polymers. It is concluded that nonlinear regression method seems to be the best method for the calculation of the discrete relaxation spectrum.
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发布时间：2021-03-19 - 摘要：The lyotropic liquid crystalline behavior of chitin is first reported.The results showed that the critical concentration decreased evidently,the average pitch of the helix on cholesteric phase decreased,but the average area of liquid crystalline ordered domain increased,as the molecular weight of chitin increased.The critical concentrations(W/W) in dichloroacetic acid were 0.005,0.015,0.035 and 0.050 respectively for chitin with the molecular weight 2.84×106,1.47×106,9.4×105 and 5.3×105 prepared from different sources.According to theoretical analysis,the chitin has a rigid chain as polypeptides. The extremely low critical cooncentration of chitin will benefit the process of chitin in liquid crystalline phase such as liquid crystalline solution spinning. In two phase co-existed concentration region of chitin with all molecular weight, no droplet texture but liquid crystalline domains with irregular shape appeared.
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发布时间：2021-03-19 - 摘要：In the presence of denaturing solvent,solutions of polypeptide can be liquid crystalline at room temperature.They may undergo an anisotropic-isotropic transition at low temperatures where the intramolecular helix-coil transformation occurs.On the basis of Florys lattice model and Zimm-Bragg's notion for the helix-coil transition,a theory considering the above phenomenon has been proposed.In this work,such theory was further developed by replacing the axial ratio x with the Kuhn chain axial ratio xk which is temperature-dependent. The calculation results show that an improved agreement between the theory and the experimental data has been achieved,and an appreciable influence on the phase behavior from both chain rigidity and polymer-solvent interaction parameterχwas found. Finally,the temperature effect on orientational parameter S was also studied. The information obtained through the investigation may find important applications,such as envisaging new routes for processing the rigid-flexible block copolymer with better mechanical properties,and helping to understand bioprocesses in the life phenomena.
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发布时间：2021-03-19 - 摘要：Non-isothermal crystallization behavior of poly(ethylene terephthalate) was studied by means of infrared spectroscopy,differential-scanning calorimetry,X-ray diffraction and density method.The PET began to crystallize as the temperature higher than 110.There isn't obvious change in the crystallinity from 160 to 230℃.But the crystallinity of PET continually increases during the later cooling process.The crystallinity of slowly cooled sample from 230℃ is much higher than that of rapidly quenched sample.These results provide strong evidence for chain folding existing before crystallization.关键词：Poly（ethylene terephthalate）;Crystallization;Infrared spectroscopy;Differential\
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发布时间：2021-03-19 - 摘要：A new reactive graft copolymer,poly(tetramethylene glycol)-graft-ω-propyl sodium sulfonate-poly(ethylene glycol)(PTMG-g-PEG-CH2CH2CH2SO-3Na+),was synthesized by the cationic polymerization of a, ω-bifunctional PEG macromonomer ( O—CH2—PEG—CH2CH2CH2SO3Na ) and THF.Polyurathane-graft-ω-propyl sodium sulfonate-poly(ethylene glycol) (PEU-g-PEO-CH2CH2CH2SO-3Na+),was synthesized by using the copolymer as a polyether.In vitro blood-compatibility tests results indicated that the sulfonate-modified polyurathane can resist platelet adhesion and is more blood-compatible.
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发布时间：2021-03-19 - 摘要：The dewetting dynamics of polystyrene(PS) blend thin films of low energy fluorocarbon chain end functional PS-F 17.3K and PS-F 35.5K with normal PS 34.5K on the 100K poly(methyl methacrylate)(PMMA) surface have been investigated.Optical microscopy was used to follow the dewetting process.XPS and AFM have been used to detect the surface segregation of fluorocarbon chain end at the surface and the equilibrium contact angle of PS droplet on PMMA.The surface segregation of low energy fluorocarbon chain end increases and the equilibrium contact angle of PS droplet decreases with increasing of the end functional polystyrene bulk fraction and decreasing of molecular weight. The segregation of fluorocarbon chain end to the surface makes the surface tension and equilibrium contact angle decrease.The dewetting velocity of PS films on PMMAwas found to decrease as a function of the surface tension and equilibrium contact angle. It is in agreement with the theoretical prediction.
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发布时间：2021-03-19 - 摘要：Refined konjac flour and Xanthan were not gelation polysaccharides.They can get geled when mixed.There was a synergistic interaction maximun when the mixed ratio of refined konjac flour and xanthan was 30/70,the total polysaccharide concentration was 1%.Studies have been made on the gelation effect of the preparation temperature (Tp) and bulk salt ionic concentration.It has been observed that, there was a jelly-glue strength maximum when Tp was 80℃ and salt ionic concentration was 0.2mol·L-1. The melting temperature of the gels (Tp) and the viscosity of melting gels will increase with increasing the salt concentration. Interaction between molecules of two polysaccharides was investigated by FTIR spectrometry.
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发布时间：2021-03-19 - 摘要：The characteristics and product structure of alternating copolymerization of styrene with maleic anhydride catalyzed by Fe(acac)3-Al(i-Bu)3 are presented and discussed in the present paper.The copolymer was characterized by IR and elementary analysis.The copolymer is a product of high alternation. Maleic anhydride and styrene are 53.3% and 46.7%,respectively in the copolymer.The copolymerization can be realized in the solvents such as aromatic hydrocarbon and alkane.The yield is higher in aromatic hydrocarbon than in the others. The third composition exerts a great influence on the copolymerization. Molecular weight and yield of copolymer are lower with the third composition of a,a'-dipyridel,8-hydroxy quindine,pyridine and acetone than that without the third cmposition. The yield of copolymer is higher with the third composition of tetrachoro-methane than that without the third composition. Molecular weight of copolymer increases as Al/Fe molar ratio increases.But the yield of copolymer dereases as Al/Fe molar ratio increases. The suitable Al/Fe molar ratio is four. The yield of copolymer increases and molecular weight decreases as concentration of catalysts increases. The suitable concentration of catalysts is [Fe]=1.5×10-2mol/L. The copolymerization can be obtained at room temperature, however,the increasing reaction temperature causes an increase of the copolymer yield and a drop of molecular weight of the polymer produced. The suitable temperature is 50～60℃. The yield and mollar weight of the polymer grow with increasing polymerization time. The kinetic studies indicate that the rate of copolymerization reaction is first order with respect to monomer concentration. E equals 48.6 kJ/mol. The reaction mechanism studies indicate that the copolyerization reaction exhibits the coordinate mechanism.
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发布时间：2021-03-19 - 摘要：Miscibility and intermacromolecular complexation between poly(styrene-co-4-vinylphenol)(STVPh) and poly(ethyl methacrylate)(PEMA) have been studied by means of differential scanning calorimetry (DSC) combined with physical aging and non-radiative energy transfer (NRET) fluorospectroscopy. Toluene which is inert to hydrogen bonding, was used as the casting solvent. Only 1 mol% hydroxyl content in STVPh was found to be able torender its iscibility with PEMA. When the hydroxyl level of STVPh was found to be able torender its iscibility with PEMA. When the hydroxyl level of STVPh is progressively increased, Tgs of the blends approach and ven exceed the values calculated from Fox equation,and the transitions become narrower. Besides, in the NRET measurements, the blends show far higher energy transfer efficiency compared with the ordinary miscible blends. All these facts indicated the complex formation between the two polymers. It was also observed that the casting solvent substatially affects the miscibility and complexation. When THF was used as the casting solvent, due to its proton-accepting ability, it partially destroied the hydrogen bonding between STVPh and PEMA in solutions and consequently hidered the miscibility in bulk. It was found that for the THF-cast blend, Tgs are 5～10K lower than those calculated from Fox equation, and the NRET efficiency is always olwer than that of corresponding toluenecast noes.
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发布时间：2021-03-19 - 摘要：The lightly sulfonated poly(phenylene oxide) (SPPO) ionomers in different mixing solvents were emulsificated by water to form a series of waterborne microemulsions.The principle of emulsification was explained.The aggregated structure of SPPO chains in organic solvents was discussed.SPPO molecular chains can form a type of microionic lattice.The emulsification process included the dissociation of the microionic lattices and aggregation of the hydrophobic segments.The polarity of solvents was an important factor for the formation of stable microemulsion systems. The effects of properties of solvent systems,ionic contents and the type of counterions on phase inversion procedure weere discussed. The phase inversion processing during emulsification of SPPO ionomers was characterized by measuring the variatio of conductivity, viscosity and surface tension with addition of water. The mechanism of the phase inversion during emulsification of SPPO ionomers was also discussed.
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发布时间：2021-03-19
Research Article
- 摘要：The conjugated poly(2-methoxy-5-butoxy) phenylene vinylene was synthesized.The intermediates and the polymer obtained were characterized by 1H-NMR and ultroviolet spectrum.The fluorescent characteristic and V-I curve and electroluminescence characteristic were measured.The results showed that the peak position of excitation spectrum was 517 nm and of photoluminescence (PL) spectrum was 547 nm and of electroluminescence (EL) spectrum was 525 nm and EL started at 5V.
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发布时间：2021-03-19 - 摘要：The energetic copolyether of 3,3-bis(azidomethyl)oxetane(BAMO) and 3-nitrato-methyl-3-methyloxetane(NMMO) was synthesized by using BF3·Et2O and 1,4-butanediol as an initiator system for the cationic ring-opening polymerization, with which the molecular weight could be controlled. The copolymer structure was characterized with FT-IR,1H-NMR and 13C-NMR. The arrangement of the monomer units in the copolyether chain is almost the ideal system. The DMA results indicated that the miscibility between the copolyether and nitrate ester plasticizer is excellent. This sopolether could be applied for solid propellant binder.
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发布时间：2021-03-19 - 摘要：A series of poly(aryl ether ketone ether ketone ketone)containing meta-phenyl link were prepared by low temperature solution polycondensation of 4,4'-diphenoxybenzophenone (DPBP),terephthaloyl chloride(TPC) and isophthaloyl chloride(IPC) in 1 ,2-dichloroethane and in the presence of AlCl3 and NMP.DSC,TGA and wide-angle X-ray scattering,etc.were used to study the general properties of the polymers.With the increase of IPC content,the Tg and crystallinity decreased,the Tm decreased at first,and then disappeared.But for all meta-linked polymer,Tm appeared once more.And this kind of polymer exhibited good chemical resistance.The structures of crystal polymer have aclose resemblance to that of poly(ether ketone ketone).The cell dimensions of copolymer containing 30% IPC were calculated to be a=0.7781 nm,b=0.6022 nm,and c=1.012 nm. The kinetics of thermal degradation of it was also studied by dynamic thermogravimetry in nitrogen. The resutls calculated from the kinetic models based on random initiation followed by rapid disproportionation and termination were in good agreement with the experimental data. The overall activation eneryg for degradation was found to be 440.0 kJ·mol-1.
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发布时间：2021-03-19 - 摘要：Polyvinyl chloride(PVC) specimens were subjected to three-point bending.The results of test and measurement show that there is a relationship of positive correlation between roughness of fracture surface and break energy per unit area.On the other hand,a certain degree of data deviation can be seen in the relationship.The deviation is principally affected by the ratios of real area of the characteristic zones on fracture surface because the effects of every characteristic zone on break energy are different.By using the synthetic effect of roughness and the characteristic zones on break energy,the degree of deviation can be sharply reduced. So,break energy can be quantitatively analysed by combining the effects of fracture surface roughness and fracture characteristic zones.
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发布时间：2021-03-19 - 摘要：The miscibility and crystallization behavior of poly(β-hydroxybutyrate)(PHB)/poly(ethylene oxide)(PEO)blends were studied by differential scanning calorimetry(DSC) and polarizing microscopy (POM).It is found that the miscibility is related to the composition of the blends.When the PEO content is over 20 percent,the miscible blends turn into partially miscible and the phase separation can be observed with POM.The addition of the PEO influences not only the morphology of PHB crystals and the radial growth rate of spherulites,but also the cold crystallization temperature.
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发布时间：2021-03-19 - 摘要：Reaction behavior of ethylene oxide in the polymerization of tetrahydrofuran initiated by H3PW12O40 was studied. The polymerization started upon addition of ethylene oxide, and stopped with complete consumption of ethylene oxide, but started again when a new portion of EO was added, and also stopped after the new portion of EO was exhausted again. Part of ethylene oxide was transformed into dioxane at the fairly beginning of polymerization in the presence or absence of water, but the formation of dioxane could be suppressed by the addition of ethylene glycol. Kinetic data showed that the concentration of propagating species maintained constant during the polymerization with stepwise addition of EO. A reaction mwchanism was postulated based on the structure analysis of the product and kinetics study.
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发布时间：2021-03-19 - 摘要：It was demonstrated that ATRP can be used successfully to obtain copolymers of styrene and N-(2-acetoxyethyl)-maleimide (AEMI) or N-phenylmaleimide (PhMI).This copolymerization system affords a predefined copolymers with low molecular weight dispersities (1.16Mw/Mn<1.36)and an alternating structure.
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发布时间：2021-03-19 - 摘要：A new iniferter,β-methacryloxylethyl 2-N, N-diethyldithiocarbamylacetate(MAEDCA),was synthesized.This compound bearing two functional groups such as methacrylate and diethylaminodithiocarbamyl groups can be used both as a monomer and a photoiniferter,respectively.Accordingly,MAEDCA belong to a monomer-iniferter.Poly-(methyl methacrylate) macromer (PMMA-macromer)was prepared by the photopolymeri-zation of MMA with a catalytic amount of MAEDCA as a photoiniferter.The monomer-iniferter and the PMMA-macromer were characterized by 1H-NMR, FT-IR, UV spectroscopies and elemental analysis. The further experiment showed that the PMMA-macromer can co-polymerize with styrene initiated by AIBN at 60℃.
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发布时间：2021-03-19
Research Bulletin
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