最新刊期
卷 ， 期 4 ， 2000
- 摘要：A series of photoluminescence materials containing europium fluorescence complex and PMMA that show high intensity of fluorescence were prepared.The fluorescence spectra demonstrated that the fluorescence intensity increased with the increasing of the content of europium complex in the film.The F-IR study showed that there are weak interaction between the complex and PMMA.The TEM results indicated that the complex crystallize in the PMMA film and the size of the particles is 100nm to 200nm.
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发布时间：2021-03-19 - 摘要：Three multifunctional alkyne derivatives were synthesized,of which N,N,N′, N′-tetrapropargyl ethylene diamine (1) and 1,1,1-tri(propargyl oxymethyl)propane (2) were used as curing agents while propargyl-terminated polyalkylene glycols (3) as a flexible chain-extender.The curing kinetics of azido-terminated polyalkylene glycols (ATPEG) of different molecular weights with 1 and 2 was investigated in details by using DSC,and the variation of the characteristic groups in the curing reaction was studied by FT-IR. It was shoun that the peak temperature and the activation energy of the curing reaction between ATPEG 1 and are higer than those between ATPEG and 2. Increasing the ATPEG molecular weight results in a peak temperature increase of the curing reaction and a decrease of the curing activation energy.When the ATPEG molecular weight is more than 1000,further increasing the molecular weignht has little influence on the curing activation energy.However,adding 3 only plyays a role of decreasing the curing activation energy of ATPEG-400 with 1.It was observed that both the increase of the molecular weight of ATPEG and the usage of the chain-extender affect the curing activation energy in same ways.
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发布时间：2021-03-19 - 摘要：A series of P(EMA-GMA)/SiO2 hybrid polymeric materials,in which there are chemical bonds between the organic component and the inorganic component,were prepared by the sol-gel process.The structure of the materials was measured by IR.It shows that C—N bonds were formed between the organic and inorganic components according to the appearence of the absorption peak at 1250cm-1 in the spectra of the product and never in those of the reacting substance.The effect of the inorganic content on the thermal behavior of materials was investigated by DSC.The results demonstrate that the values of Tg and feasible temperature increased with increasing of the inorganic component.In the same time,each sample displays a single value of Tg,it may be attributed to the little phase separation in the materials.The morphology of hybrid polymeric materials was determined by means of TEM and SAXS.From theoretical calculation of parameters a1,a/2,Ssp,liand l。with the Guinier and the Debye equations and TEM analysis,the regulation effect of the inorganic content and acid content on the compatibility of the two components was concluded.The results show that the material possesses a wonderful compatibility when the molar ration of 3-aminopropylsilane (APTES) and copolmer is 1:1and the acid content is 1.5%(Vol%).The relationship between the transparency of the hybrid materials and the reaction conditions was also discussed.
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发布时间：2021-03-19 - 摘要：A novel epoxy-terminated polyaryletherketone(E-PPEK)was synthesized by the reaction of epichlorohydrin with PPEK oligomer prepared by nucleophilic substitution of 4,4′ -difluorobenzophenone(DFK) with 4-(4\|hydroxyphenyl)-2,3-phthalazine-1-one.E-PPEK samples were characterized by FT-IR and 1H-NMR spectra,and their solubility was also determied.
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发布时间：2021-03-19 - 摘要：The so-termed hyperbranched polymers differ from classical polymers by their high degree of branching, high density of terminal functionality, and three-dimensional molecular structure. The divergent synthesis of a series of polydisperse hyperbranched poly(amine-ester)s based upon 1,1,1 -trimethylolpropane (as a core molecule) and N,N-diethylol-3-amine methylpropionate (as an AB2 monomer) synthesized via Michael addition of methyl acrylate and diethanolamine is described, proceeding in a stepwise growth manner starting from an "initiator core"building branched arms,i.e.,pseudo-one-step manner,or a one-step procedure in the melt sing P-TSA as catalyst.These materials have different numbers of hydroxyl groups at the chain extremities on each molecule.The moleculat composition of hyperbranched poly(amine-ester)s prepared using the pseudo-one -step procedure have narrower molecular weight distrbutions than the products obtained by using one-spot procedure as detected by GPC.The rheological behavior of the hyperbranched poly(amine-ester)s was investigated using a spinning viscometer. The viscosity is reduced sharply as the temperature increases.The thermal property has been also estimated.The hyperbranched poly(amine-ester)s,synthesized in this study,may be modified to meet particular application requirements for coating,lamination,and adhesive systems.
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发布时间：2021-03-19 - 摘要：Polyphenylquinoxaline (PPQ-E) is an aromatic heterocyclic polymer with high performance and water resistance at high temperature.It was synthesized form aromatic tetraamine and aromatic tetraketone by condensation polymerization.The influence of physical aging on structure and mechanical properties of polyphenylquinoxaline has been studied.The free volume and cohensional entanglement structure of samples preapared under two different thermal conditions were measured by positron annihilation life spectroscopy (PALS) and DSC.For samples which underwent physical aging an endothermic peak at the end of the glass transition was observed in a heating process.It means more cohensional entanglement stucture forms during physical aging.The results of PALS show that physical aging may reduce the free volume in samples.A little increase of storage modulus in the temperature range from 100℃to300℃ and a decrease of mechanical loss at 250～300℃ result form physical aging.The tensile mechanical test manifest that physical aging may result in a decrease of fracture strain and energy,an increase of yield stress and a transition from ductile to brittle generate for PPQ-E samples.
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发布时间：2021-03-19 - 摘要：The polymer loop discussed in this paper was defined as a polymer chain,both ends of which are attached to a surface of impenetrated wall.In order to obtain the configurational statistics of this polymer loop,the exact enumeration and Monte Carlo methods were applied to the model of self-avoiding walk(SAW) on two- and three dimensional lattices.For the SAW on the simple cubic or square lattice,the maximum length of the model chain loop was 29 and 19,respectively.The numerical results based on the simulations were fitted to the scaling theory,by which the scaling exponents and other parameters were obtained and compared with the corresponding theoretala values.It was shown in the simulations that for these SAW loops the parallel components of their sizes with respect to the surface of the confined wall were larger than the perpendicular ones.It was interesting to notice that these results are contrary to those for the corresponding model tail chains,only one end of which is attached to the surface.
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发布时间：2021-03-19 - 摘要：The spherulite growth of hard segments in polyurethanes and its relation to the compatibility between the soft and hard segments were studied.DMA and DSC measurements indicate that polyurethane with different soft segments(PCL,PTAM,PTMO and PPO) exhibit different compatibility between their soft and hard segments.The compatibility between hard and soft segmeats in polyurethanes decreases in a sequence of PCL,PTMA,PTMO and PPO.The temperature range for hard segments of polyurethane to grow spherulites in annealing from melt is limited.The better the compatibility between the soft and hard segments,the narrower the temperature range for spherulite formation and the longer the crystallization time.The low temperature limit of spherulite growth is 120℃ for polyurethane with MDI-BDO hard segments and does not change with soft segments.This limit is determined by the hydrogen bonds between the hard segments and soft segments.The high temperature limit of spherulite grouth strongly depends on the compatibility between the soft and hard segments.The worse the compatibility,the higher the high temperature limit Only when the temperature becomes high enough,the compatibility between the soft and hard segments can prevent the forming of spherulite.When the hard segments crystallize from melt,there exist a most appropriate temperature of forming spherulites,at which the amount of hydrogen bonds has a maximum as shown by FTIR In such cases the crystallites and spherulites are more stable.
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发布时间：2021-03-19 - 摘要：The accuracy and robustness of Lagrangian-Eulerian method on benchmark problem of viscoelastic flow through complex geometries was tested.The test is performed by directly comparing the numerical predictions of flow through a 4∶1 planar contraction with the experimental observations in order to ensure whether the method is physically correct.The one-mode Phan-Thien and Tanner(PTT) constitutive model is used in the present calcuation.Profiles of both velocity and stresses are obtained at different sections of the steady flow,and compared with laser Doppler velocimetry and flow-induced birefringence data given by Quinzani et al.for a polysisolbutylene/tetradecane(PIB/C14) contraction flow at a Deborah number De=3.0.Overall,the simulation has reproduced the expermiental results with good accuracy,the agreement between the numerical predictions and the experimental reports is fairly well.
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发布时间：2021-03-19 - 摘要：The preparation of syndiotactic polymers through ring-opening polymerization of a chiral monomer bearing one asymmetric center in the ring was not found in literature.This paper presents the synthesis and properties of syndiotactic poly(phenyl glycidyl ether)(PPGE).Phenyl glycidyl ether was polymerized under the effect of Bu2SnO-Bu3PO4 condensates (Sn P).The tacticity of the obtained PPGE was dependent upon the structure of the catalyst.The Sn-P condensate obtained through a condensation reaction at 220～260℃ for 30～60 min,and then at 150～220℃ for 1h had two kinds of stereoselective center.Syndiotactic-rich PPGE fractions (s-PPGE) were separated from the polymerization products obtained using Sn- 8000,a condensate prepared by the two-step condensation,as catalyst.The yield of the s-PPGE fractions reduced as the polymerization temperature enhanced,indicating the activation energy for the syndiotactic center in the catalyst is lower than that for the isotactic center.Compared to the insoluble character of isotactic PPGE (i-PPGE) in any known solvents,s-PPGE can be dissolved in solvents such as chloroform and toluene.The crystallization ability of s-PPGE is lower than that of i-PPGE. The thermal induced crystallization of s-PPGE is very slow.However in the presence of an appropriate solvent such as acetone,it may crystallize quickly.
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发布时间：2021-03-19 - 摘要：A highly active supported metallocene catalyst for propylene isospecific polymerization was prepared by immobilization of SiO2 with precontacted compounds of rac Me2Si(Ind)2ZrCl2 and methylaluminoxane (MAO).The influence of [Al]/[Zr] ratio and polymerization temperature on the activity,molecular weight (Mw) and polymerization kinetics was investigated.The behavior of this catalyst was also compared with its corresponding homogeneous catalytic system.It was demonstrated that the active site of heterogeneous systems was more stable,and the Mw of catalysts was determined by 13C-NMR spectra.It was found that the isotacticity of iPP obtained by heterogeneous systems was higher,ist pentad sequence [mmmm] increased to 86.3% from 82.0% for homogeneous systems. Moreover,the regioselectivity of polmers produced by heterogeneous systems was also improved,the 2,1-insertion and 1,3-insertion decreased to 3.7%。and 0.5%。 from the values of 4.4%。and 1.9%。,respectively for those produced by homogeneous systems.
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发布时间：2021-03-19 - 摘要：The rheological properties of concentrated aqueous solutions of water-soluble polyesters prepared by copolycondesation of dimethyl terephthalate,iso-phthalic acid,dimethyl 5-sodiosulfoisophthalate with ethylene glycol,have been investigated.The concentrated aqueous solutions (30%) of water-soluble polyesters show a weak shear-thickening feature with flow index from 1.04 to 1.20.Their lgηa-τcurves show a linear feature,and the zero shear viscosity varies with molecular structure,molecular weight and temperature.Specially,the content of bis(2-hydroxyethyl)5-sodiosulfoisophthalate in molecular chains has a large effect on the viscosity of solutions.Ther viscosity-flow activation energy varies with molecular structure of the polymer and the shear rate in a range of 12.0-23.9kJ/mol.
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发布时间：2021-03-19 - 摘要：poly(εcaprolactone) (PCL) and silica (SiO2) organic-inorganic hybrid materials have been synthesized by sol-gel approach and the crystalline behavior of PCL in the silica networks has been investigated by differential scanning calorimetry (DSC) and wide angle X-ray diffraction (WAXD).The degree of PCL crystallinity in the PCL/SiO2 hybrid networks reduces with the increase of SiO2 content.PCL is in an amorphous state when the concentration of PCL is lower than 40wt% in the hybrid materials.The melting points of PCL in the neworke are lower than that of pure PCL,but they almost have a same value.WAXD results show that when the PCL weight percentage is higher than 40wt% in the hybrid samples,part of PCL can crysatllize and the PCL crystallites are almost in a same size.That means the crystalline movement of PCL molecular chains is strictly confined by the porous gel.The crystalline PCL in the hybrid samples is relatively free from the composition of the materials,because the crystallization temperature and melting point of PCL of the samples are almost equal,and the crystalline PCL of different samples has the same crystalline structure and the same crystallite sizes L110 and L200,that means the crystalline part of PCL in the hybrid samples is unperturbed and the porous silica gel gives enough space for PCL to crystallize into the same crystalline structure and the same size crystallites.
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发布时间：2021-03-19 - 摘要：A novel polymide hybrid composite material for gas separation membrane was prepared by thermal imidisaton of the blend of poly(amic acid) and transitional metal organic complex.The poly(amic acid) was synthesized by condensation polymerization of hydroquiuone diphthalic anhydride or bistolueneketone dianhydride with methylene dianiline.The performance of obtained metal organic complex-polyimide hybrid materials was investigated.The results showed that all the obtained hybrid materials kept the traditional advantages of polyimides in mechanical properties,thermal resistance and chemical resistance.The structure of obtained polymide materials was characterized by WAXD and liquid balance.The experimental results indicated that the addition of transitional metal organic complex can increase the d-spacing of polymide molecular chains.As a result,compared with the corresponding polyimide,the permeability coefficients of the obtained polyimide hybrid materials can increase about 40% and the permeation selectivity varied slightly.
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发布时间：2021-03-19 - 摘要：The cyclization of cis 1,4 polybutadiene in various solvents (mesitylene,xylene,toluene,benzene and cyclohexane) with the catalyst composed of CH2 CHCH2Cl-AlEt2Cl was studied.The infrared spectra of the cyclized products were investigated.It was shown that the products produced in cyclohexane and mesitylene have infrared spectra identical with those of the original cis-1,4 polybutadiene and the products obtained in other aromatics have infrared spectra different from each other and distinguishing with those of the pqrent cis-1,4 polybutadiene.The analyses of cis-1,4 polybutadiene at the given condition.Apossible reaction scheme involving and electrophilic substitution of carbonium ions for Ar—H of aromatic solvents was proposed.Some experimental facts wereexplained with great satisfaction on the basis of the above mechanism.
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发布时间：2021-03-19 - 摘要：Poly (propylene glycol-g-styrene) was synthesized by CuCl-catalyzed atom transfer radical polymerization (ATRP) of styrene(St) with chloromethylated phenoxy poly(propylene glycol) (CMPOPPG) as the macroinitiator. CMPOPPG was prepared by ring-opening polymerization of propylene oxide and glycidyl phenyl ether (GPE) following by chloromethylation. The grafting polymerization exhibited characteristics of controlled polymerization. Graft copolymers were confirmed by size exclusion chromatography (SEC), 1H-NMR and microcoulometry. The molecular weight of the grafts can be controlled.The graft ratio was as high as 8.6.
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发布时间：2021-03-19 - 摘要：The influence of a transition metal acetylacetone catalyst on the behavior, mechanism and product structure of the co-curing of epoxy and cyanate was studied by DSC and FT-IR. The results reveal that the catalyst can accelerate the curing of the resins decreasing the curing temperature and time. The reactions involved in the co-curing are: cyclodimerization and cyclotrimerization of cyanates, polyetherfication of epoxy groups and cyclotrimerization of cyclic dimers, as well as the formation of oxazolidinone rings. In the lack of cyanate functional groups,the main structures of cured compounds are oxazolidinone and polyether structure in the cured resin, and the triazine ring structure is of minor importance. In the excess of cyanate functional groups,the main structures are triazine ring and oxazolidinone structures in the cured resin,and the polyether structure is of minor importance.
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发布时间：2021-03-19 - 摘要：In order to explore structural specialty on reactivity of peroxides,the oxygen-oxygen bond dissociation energy,the oxygen net charges and the calibration charges of free radicals have been caculated via molecular mechanics and AM1 method for decades of organic peroxides.Multiple linear regression was performed for the calculated data with 10h-HLT,which is a kinetic parameter in literature.Results show that the oxygen-oxygen bond dissociation energies of the examined peroxides are not correlated with their 10h-HLT parameters.Since the thermal homolytical cleavage of the peroxide is a reversal process,is includes the decomposition of the parent peroxide and the recombination of the oxygen-centered free radicals.The interaction of the free radicals in the recombination was considered significant.Obtained results indicate that the electronic structure and the spatial topology of radicals mostly influence reactivity of the peroxides.The more the absolute of oxygen charge densities in the free radicals,the easier the dissociation of the parent peroxide.Is was found that the oxygen net charge and the calibration charge of radicals play the key roles in characterization of the reactivity of the peroxides.In the same solvent the four factor linear regression is mostly obeyed between the 10h-HLTs of the parent peroxides and the two oxygen net charges and the two calibration charges for two free radicals.The 10h-HLT valus have thus been predicted by using a correlation with the four factors.
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发布时间：2021-03-19
Research Article
- 摘要：Metallic organic compounds of iron, stannum and manganese were introduced into lowdensity polyethylene as catalysts of degradation at low temperatures. The mechanical properties, viscosity-average molecular weight of polyethylene and the hydroperoxide concentration in the matrix were measured. It was shown that at 70℃ the adopted additives can catalyze the degradation of polyethylene efficiently. After 60 day's aging, most of the samples became very fragile, and their molecular weight decreased in large scales. The relationship between moecular weght and hydroperoxide concentration,as well as the mode of the degrading behavior of the prepared matrixes,was also discussed.
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发布时间：2021-03-19 - 摘要：The dynamics of living polymerization of styrene was studied with alkyllithium/potassium alkoxide as bimetallic initiator and cyclohexane as solvent. It was found that the apparent propagation rate constants (kap )increased greatly with little increasing of K/Li ratios and in linear relationships with the concentrations of potassium alkoxide ([POK])when K/Li ratios were lower that 0.1. And the slopes of kap-[ROK] lines increased with the decreasing of alkyllithium concentrations. This dynamics feature can not be explained quantitatively by the ordinary association dynamics model which ignored the cross-association between the propagation species with different metallic ion. In this paper, a new dynamics model on cross-association concept was established and the dynamics feature of living polymerization of styrene can be interpreted satisfactorily.The propagation rate constant of potassium species(kk) and the constant group,(K1/2)0.5/K3,of dissociation constants of cross-association species (K3) and lithium species (K1) were derived by curve fitting and led to values of 7.1×103(mol/L)-1min-1and 67(mol/L)-0.5respectively at a polymerization temperature of 50℃.
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发布时间：2021-03-19 - 摘要：A novel poly(1-butene) was synthesized with η5-pentamethylcyclopentadienyl-tribenzyloxytitanium(Cp*Ti(OBz)3) and modified methylaluminoxane(MAO). The influence of various conditions (e.g., catalyst composition, temperature, Al/Ti, pressure of monomer, and catalyst concentration) on the catalytic activity, molecular weight of the products were investigated in detail. It was found that the catalyst exhibited highest activity of 91.3kgPB/molTi·h at T=30℃, and Al/Ti(mol/mol)=200. The catalytic activity and molecular weight were sensitive to the TMA content in MAO and external TIBA.Cataltiac activity and molecular weight were decreased with increasing the content of TMA in MAO.External addition of TIBA can deactivated the catalyst.Molecular weight of the products was increased with decreasing temperature and Ti conentration.The catalyst had the highest activity at a Ti concentration of 1.0×10-3mol/L.The molecular weight of poly(1-butene) is high,over one million by GPC method.The results showed that with this catalyst system,a high molecular weight poly(1-butene)can be synthesized.
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发布时间：2021-03-19 - 摘要：Several methods were chosen to try to synthesis polyaniline(PAn)-graphite oxide (GO) composites in this paper. It was experimentally shown aniline could be easily inserted into GO layers, however, lower oxidative potential could not oxidatively polymerize the intercalated aniline to form polyaniline intercalated graphite oxide nanocomposite(Comp.Ⅱ). And also, when aliline intercalated GO was externally oxidized by aqueous FeCl3 or (NH4)2S2O8/HCl, a polyaniline encapsulated GO composite (Comp.I) could be only obtained. But when an exfoliation/absoprtion process was used,where polyaniline was in situ polymerized in exfoliated GO suspension,Comp.Ⅱcould be obtained.Otherwise,XRD,FT-IR andDSC were used to characterize these composites.XRD measurements indicated the Ic value of comp.Ⅱ increased from 7.62nm of GO to 1.78nm,which suggests that there exists a single layer or /and bilayer of PAn chain in the GO layer.Data of FT-IR measurement indicated the co-existence of GO and Emeraldine Salt in the polymer intercalated GO,very likely accompanied by an existence of Emeraldine Base.Thermal analysis also showed that the thermal behaviors of Comp.Ⅱwere different from those of Comp.I. And contrast to pristine GO,these two composites had a higher electrical conductivity σ, but Comp.Ⅱhad a much higherσ value than Comp.I. due to the synergies of polyaniline and graphite oxide in Comp.Ⅱ,especially the chemically reduced Comp. Ⅱand the reduced Comp.Ⅱwas 1.45×10-3S/cm and 3.73×10-2S/cm,respectively.
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发布时间：2021-03-19 - 摘要：The crystallization of the α-and β-form crystals of syndiotactic polystyrene (sPS) is determined by the crystallization temperature. Being crystallized at various temperatures from the melt, sPS forms the β form crystal at high temperatures above about 230℃, α form crystal at low temperatures below about 170℃ and a mixture of the α and β form at intermediate temperatures. The effect of different cooling rates is considered in more details. Since the β form crystallizes at high ttemperature from the melt.It will first crystallize during cooling.At low cooling rates,the crystalline phase of the βform has almost reached the maximum crystallinity of the sample by cooling to 230℃.Soeven the temperature for the a form formation is reached,there is no more crystallizable sPS portion remaining for the a form formation.That is the reason why the βform is always obtained by cooling at a slow or moderate rate.If cooling reate is high enough that the βform has almost no time to crystallize at high temperature,only the a form can crystallize at low temperature.That is the reason why only the a form crystal is obtained under quenching conditions.It clearly indicates that the crystallization temperature is the intrinsic factor controlling the formation the a- and β-form crystals.
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发布时间：2021-03-19 - 摘要：Poly(ether ketone ether ketone ketone) containing meta-phenylene linkage (PEKEKK(T/I)) was synthesized by electrophilic Friedel-Crafts acylation condensation of 1,4-diphenoxybenzophenone with terephthaloyl chloride (T) and isophthaloyl chloride (I) with a T/I ratio of 1 and characterized by IR、DSC、TGA and WAXD. PEKEKK(T/I) has two different crystal structures: a conventional Form I structure, the same as that observed in PEEK and PEK, wich is usually developed from melt crystallization, and a new Form Ⅱ structure which can bedeveloped from cold crystallization or solvent induced crystallization (by exposing the glassy sample to methylene chloride).
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发布时间：2021-03-19 - 摘要：Miscibility of the fibroin, which was soluble in CaCl2-H2O-C2H5OH aqueous solution, mixed with chitosan was investigated, and its microspheres were prepared. The chitosan (CS)/fibroin (FB) microsphere inclusion fenoprofen calcium (CS-FB-FC) was prepared, and its structure was analyzed by FTIR, X-ray and SEM. The results indicated that blend of chitosan, fibroin and fenoprofen calcium in aqueous solution is miscible, and strong interaction caused by intermolecular hydrogen bonding exits in CS-FB-FC. It was indicated that approximately the initial 6h,and with increasing the glutaraldehyde concentration,the release of fenoprofen decreased.
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发布时间：2021-03-19 - 摘要：The polymerzation of tetrahydrofuran (THF) initiated by heteropolyacid—H3PW12O40 in low concentration could be promoted by oxetane (OX), but the polymerization stopped at lower conversion than that promoted by oxiranes. The chain structure analysis by NMR spectra showed that OX was more reactive toward polymerization than oxiranes and more than 80% of OX were consumed through copolymerization, but not initiation. By stepwise addition of OX the conversion of THF polymerization could be increased higher than 50%.The percentage of the hydroxyl group attached to OX moieties at the polymer chain-ends was higher than 50% of the total hydroxyl end-groups,inferring that polymerization proceeded quite similar to that promoted by ethylene oxide and each chain wasstarted with the OX moiety.
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发布时间：2021-03-19 - 摘要：A group of polyethylene-carbon black (PE-CB) composites was prepared with different CB volume fraction and the dependence of conductivity on the CB volume fraction was measured. The conductive percolation phenomenon of those composites was studied by Monte Carlo method. It was supposed that the conduction of those composites was not only dependent on the contact pathway formation but also on the quantum mechanical tunnel formation. The put in particle number dependence of “the conductive conjunction” number and “the average particle number”in the partial conducting pathway was showed in three figures,respectively.The typical CB particle conjunct states obtained by Monte Carlo method were illustrated with “the conductive conjunction”,“the partial conducting pathway”in different marks.Thus it vividly demonstrates the internal reason for the conductive percolation of the PE-CB composites.It is worh notice that only more than 50% CB particles are connected together to form the conducting pathway when the conductive percolation takes place,and that in the system there still exist some partial conducting pathways.The later does not make contribution for the conductivity of the PE-CB composites.
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发布时间：2021-03-19 - 摘要：Phase inversion emulsification technique is an effective physical method to prepare waterborne dispersions of polymeric resins In this study,a multi-hollow epoxy resin sphere was obtained by incompletephase inversion emulsification．The dynamic morphological evolution of water droplets dispersed in bisphenoL A epoxy resin／emulsifier (a multi-block copolymer)during phase inversion process was investigated with scanning electron microscopy．It is shown that small discrete water droplets are dispersed in the epoxy resin continuous phase at low water content. In this case．the dynamic coalescence among the small water droplets is ignored．With increasing water content,the dynamic coalescence becomesremarkable and larger water drops are formed by the coalescence among the small water droplets The larger water drops are randomly distributed within the continuous phase．Meanwhile,some necklace like structures with varied length co-exist with the small water droplets and larger water drops Incomplete phase inversion is achieved through the coalescence among the larger water drops,and some small water droplets are entrapped therein．In this caSe,a kind of multi-hoHow sphere is obtained．While．in some local regions,all the nearest small water droplets coalesce simultaneously to be continuous phase to achieve complete phase inversion,and small discrete waterborne particles are obtained The dynamic coalescence among the small water droplets dispersed in epoxy resin continuous phase could be analyzed in terms of theimproved Smoluchowski equation．
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发布时间：2021-03-19 - 摘要：The measured reduced viscosity-concentration (ηsp/c-c) curves of miscible PPO/PS、 immiscible PMMA/PS mixtures with different composition in toluene all deviate from linear and reveal downward turn in extremely dilute concentration region. Moreover, in the extremely dilute concentration region, the ηsp/c-c curve of immiscible PVC/PS mixture solution shows upward turn in THF, while shows downward turn in DCE. These experimental facts indicate that such viscosity anomaly is not dependent of miscibility,but resulted from wall effects.Regarding the polymer mixture as a single solute,the interference of wall effects on viscosity measurement could be eliminated quantitativle with a proposed theoretical formula. After corrected,the true viscosity data of mixture shows normal linear ηsp/c-c curve in the dilute and extremely dilute concentration region.
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发布时间：2021-03-19
Research Bulletin
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