最新刊期
卷 ， 期 1 ， 2001
- 摘要：A novel family of polymeric surfactants based on carboxymethyl cellulose (CMC) was synthesized through ultrasonic irradiation.The experimental results show that the polymeric surfactants produced are block copolymers having low surface and interfacial tension,comparable to those of low molecular weight surfactants.The high molecular weight of the polymeric surfactants has only limited infulence on surface and interfacial activity.The excellent properties displayed by the polymeric surfactants result from the special blocky structure obtained during ultrasonic irradiation.CMC blocks contribute to the high viscosity and the surface active macromonomer blocks contribute to the high surface activity.
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发布时间：2021-03-19 - 摘要：The morphological structure and properties of gels prepared from partially hydrolyzed polyacrylamide (HPAM) and aluminum citrate (AlCA) were studied through optical microscopy,scanning electron microsopy and rheological measurement.Experimental results show that the gels prepared from solutions containing HPAM and AlCA appear in three typical states with the increase of HPAM concentration:the dispersed gel,the gel containing both dispersed and continuous network phase and the gel with continuous network structure.The dispersed gel contains particles composed of crosslinked HPAM macromolecules and its increase in viscosity is not evident.For the gel with continuous network structure ist complex viscosity and complex modulus are markedly raised and the crosslinked HPAM particles are connected with each other in a network.
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发布时间：2021-03-19 - 摘要：A novel technique to optimize the morphology and thus to enhance the mechanical properties of polypropylene(PP)／polyamide 6(PA6) system was reported in this paper．Through pan-milling at ambient temperature．PP／PA6 pellets of particle size 2～5mm can be effectively pulverized down to well mixed micro-meter or even to nano-meter scale powders By press molding the obtained ultra-fine PP／PA6 powder at a terllperature between the meh points of PA6 and PP(say,200℃),a ultra-fine PA6 particle filled PP blend can be obtained,in which PP is the matrix,and PA6 powders maintain at solid state and are dispersedin PP matrix at micrometer scale Morphological analysis shows that the domain size of PA6 in the system is much smaller than that of PP／PA6 blend and is similar to that of PP／PA6 blend compatibilized by PP-g-MAH The mechanical properties of the system is much better than those of the PP／PA6 blend．The tensilestrength of the ultra-fine PA6 particle filled PP／PA6(70／30) blend is 29．3MPa,which is 6．1MPa higher than that of the PP／PA6 blend．lzod notched impact strength of the ultra-fine PA6 particle filled PP／PA6 (70／30) blend is 6.34kJ／m2,which is 1.72kJ／m2 higher than that of the PP／PA6 blend These properties are comparable with those of the PP-g-MAH compatihihzed PP／PA6 blend,i.e.,pan-milling has the similar compatibilizing effect on PP／PA6 systems as that of incorporating a compatibilizer．
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发布时间：2021-03-19 - 摘要：The conformational variation of a polymer chain terminally attached to a surface at different temperatures was studied by using Monte Carlo and simulated annealing methods．The model polymer chain was a self-avoiding walk with non-bonded nearest-neighbor interactions on a simple cubic lattice It was shown in results of computer simulations that in dilute solutions the tail chain,like the free chain,undergoes the phase transition from a loose coll to a compact globule when the temperature decreases．The mean square end-to-end distances and their components,as well as the mean square radius of gyration and their distributions were calculated at different temperatures Due to the existence of the surface,the curves expressing the chain size versus temperature for the tail chain were slightly lower than those for the free chain．It was also found that the effect of the surface on the shape of the polymer chain was obvious at high temperature,and the perpendicular component of mean square end-to-end distance was significantly larger than the parallel component However,below the θ temperature,especially after the full collapse of the polymer chain,the effect of the surface on the chain shape becomes very small．
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发布时间：2021-03-19 - 摘要：Diphenylacetylene was polymerized by di(cyclpentadienyl) titanium dichloride with irradiation of light over 423K.The structure and properties of poly (DPA) were studied by using IR,MS,thermal analysis,X-ray crystalline diffraction and electrical conductivity measurements.The poly (DPA)-A was rigid, cis -cisoidal,pseudohexagonal packing of rodlike molecules and crystallized over 95%.The first crystalline diffraction peak was at 2θ=7.1°.The lateral spacing 1.26nm,calculated from the diffraction pattern,can be interpreted as the (10 10) diffraction of the pseudohexagonal lattice.The nearest chain-to-chain distance or the diameter of the molecule was 1.46nm.The IR absorption at 1179,1156cm-1was due to the cis-cisoidal characteristic vibration.The activation energy of the polymerization was 2.6×105J/mol.The crystalline poly(DPA) was stable up to temperatures varying between 493K and 573K.Only one endothermic peak that occurred at 713K was observed witha a weight loss of polymer up to 10% This endothermic peak is explained in terms of the melting of the polymer,hydrogen migration and scission of the main chain The poly (DPA)was not obtained in the presence of diphenyl ketone or DMSO at 443K.The pathway of the polymerization was discussed.
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发布时间：2021-03-19 - 摘要：A series of monomers (methacryle,acrylate and styrene)were polymerized by controlled／living radical polymerization in bulk using Reversible Addition-Fragmentation chain transfer (RAFT process)．A detail purification process of chain transfer agent (CTA) dithioesters (2-phenylprop-2-yl dithiobenzoate and 1-phenylethyl dithiobenzoate) was described．Results of styrene (St),methyl methacrylate(MMA),ethyl methacrylate(EMA),butyl methacrylate (BMA),octyl methaerylate (OMA),methyl acrylate (MA),ethyl acrylate (EA) polymerization using the AIBN／CTA(mole ratio 1：4) initiating system at 70～100℃ confirmed the living polymerization characteristics Diblock copolymers(PMMA-PEMA,PEMA—PMMA．PBMA-PMA,PBMA PEA,PSt-PBA) with well defined structures as well as controlled and narrow molar mass distribution were obtained from the lower．mass macroinitiator．The living character of the RAFT processisindicated bythe narrow polydispersity product(1．1～1．3),alinearmolecularweight-conversion profile,the predictability of the molecular weight from the ratio of monomer consumed to transfer agent and the ability to produce block copolymer by further monomer addition．In each reaction step．the effects of conversion and reaction time on the molar mass characteristics of the prepared block copolymers were investigated．The SEC curves shift toward lower elution volumes as the reaction time increases While the polydispersity remained low and there was no detectable amount of unreacted starting maeroinitiator block as analyzed by GPC．When highmolecularweight startingmacroinitiator (Mn>30000) was used,therewas a substantiallow molecular weight shoulder observed．
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发布时间：2021-03-19 - 摘要：The present article delt with empolying o,o′ diallyl bisphenol A ether (DBAE) grafted polyethylene (DBAE-g-PE) as a compatibilizer to improve the compatibility of the polycarbonate/polyethylene alloy.An amazing toughening phenomenon was observed in the alloy containing 15phr PC and 5phr DBAE g PE through testing the impact strength and the critical strain energy release rate(G1C ).The results from the fracture surfaces of the polycarbonate/polyethylene alloy observed by a scanning electron microscope (SEM) indicate that the neat alloy without compatibilizer displayed a brittle fracture morphology,while for the alloy compatiblized with DBAE-g-PE,both matrix and dispersed phase had high surfacial contact,and the dispersed polycarbonate particles were plastically deformed into fibres,which was brought out beacause of the impact compressure exerted by the PE matrix in the process of impacting and the exellent compatible effect between PC and PE caused by the dompatibilizer,DBAE-g-PE.A fibre formation based toughening mechanism was preaented,combined with a structural diagram,to analysize the amazing toughening phenomenon in the compatibilized polycarbonate/polyethylene alloy.
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发布时间：2021-03-19 - 摘要：The kinetics of nonisothermal crystallization has been studied for sulfonated syndiotactic polystyrene (SsPS) containing 1.60mol%,3.05mol% and 4.41mol% sulfo groups,and pure syndiotactic polystyrene (sPS) by means of differential scanning calorimetry (DSC) at various cooling rates.The theory of Mandelkern and the method of Mo Zhishen for nonisothermal crystallization are used to analyze the DSC data.The results show that the crystallization behavior of SsPS exhibits considerable differences in comparison to the neat sample.The degree of crystallinity and the rate of crystallization are significantly lowered by the presence of sulfo groups.The noninteger Avrami exponents,between 2 and 3,for sPS and SsPS samples during nonisothermal crystallization procedure indicate that a mixture of mucleation and growth mechanisms are occurring.On the other hand,the quite comparable Avrami exponents for the sPS and SsPS samples suggests that sulfonation does not significantly alter the observed crystallization mechanism of sPS.In addition,the crystallization activation energies for nonisothermal crystallization are evaluated to be 240.50kJ/mol for sPS,and 251.70kJ/mol,272.33kJ/mol and 290.79kJ/mol for SsPS containing 1.60mol%,3.05mol% and 4.41mol% sulfo groups,respectively.
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发布时间：2021-03-19 - 摘要：Electrically conducting nylon 6/graphite nanocomposites were elaborated via intercalation polymerization.Room temperature electrical conductivity measurement reveals a threshold of ∮*= 0.75 vol% which is much lower than that of conventional conducting polymer composites.The electrical conductivity of the nanocomposite reaches 10-4 S/cm at 2.0 vol% graphite content.The TEM microphotographs verified that the low percolation threshold and improvement of conductivity could be attributed to the large diameter to thickness ratio,the high expansion ratio in c axis of the graphite sheets and the homogeneously dispersion of graphite particles with nanoscale thickness in the nylon 6matrix. Because of the high expansion ratio (generally 200～300) of expanded graphite in c axis there are many pores of different sizes ranging from 10nm to 10μm in the internal space of graphite.Thus suitable monomer molecules and/or catalysts can be easily intercalated into the gallery spaces of graphite through physical adsorption.This is the main reason that in-situ polymerization can be initiated in the galleries of expanded graphite.
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发布时间：2021-03-19 - 摘要：A stereo block poly(1-butene) was synthesized with η5-pentamethylcyclopentadienyltribenzyl-oxidetitanium(Cp*Ti(OBz)3) and modified methylaluminoxane(MAO) as catalyst.The original polymer was extracted successively by boiling ether and heptane, and each fraction was characterized by 13C-NMR, WAXD and DSC. It was found that ether soluble fraction was atactic poly(1 butene), heptane solube fraction was stereo block poly(1-butene), and heptane insoluble fraction was isotactic one. The isotacticity,glass transition temperature and crystallinity of the polymers soluble in boiling heptane were increased with decreasing polymerization temperature.At lower polymerization temperature (30℃ and 0℃),the polymers with the degree of crystallinity over 30% had two melting peake which were 43℃/55℃ and 85℃/88℃,respectively.But at higher temperature (40℃) noncrystalline polymer obtained from heptane-solube fraction was characterized by WAXD and DSC.The relationship between the propagation mechanism and the microstructure of the prepared products was studied by 13C-NMR. It was indicated that the 1,2-insertion was easier than 2,1-insertion.
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发布时间：2021-03-19 - 摘要：A series of well-defined graft vinyl ester resins(graft VER),i．e．butanol(BO),poly(oxy-propylene) with different molecular weights (200 or 390),which were simply called as 130-g-VER,200-g-VER and 390-g-VER respectively,consisting of different kinds and lengths of the side chains were synthesized and characterized．The simultaneous interpenetrating networks(SINs) of graft VER and polyurethane．urea (PUU) formed with toluene diisocyanate have been prepared．The effect of graft VER structure on the morphology and mechanical properties of PUU／graft VER SIN was studied through DSC and SEM observation etc．For PUU／BO-g-VER SIN,the BO-g-VER network is mainly interpenetrated and miscible with the hard segments of PUU network．For PUU／200-g-VER SIN,there have some interpenetration and miscibility between the 200-g-VER network and the hard segments as well as soft segments existing in the PUU network Thus,the strong reinforcement effect of these two graft networks on the PUU network was observed,and the mechanical properties of SINs were enhanced appreciably．There exhibited obvious phase separated morphology between the two networks in PUU／390-g-VER SIN,because of existing microphase separated morphology of 390-g-VER network in itself．In this case,theenhancement effect of such a graft VER network on the PUU network is limited
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发布时间：2021-03-19 - 摘要：In order to develop and apply the silk sericin protein in functional polymeric materials, the co-ordination reaction of sericin with copper(Ⅱ) ion in aqueous solution is studied by measurements of pH titration and optical spectra, and the coordination structure of the formed complex at high pH as well as its higher order structure are investigated by electron spin resonance(ESR) spectra and X-ray diffraction. When the pH value is over 9.1 or so, each Cu2+ consumes about four OH- ions, and the optical absorption band lies at 540nm,which indicate that the type of Cu2+-protein biuret complex is formed.And the ESR spectrum shows that the unpaired electron of copper(Ⅱ) in the complex localizes in the ground state of dx2-y2 orbit.So it is put forward such coordination structre as Cu(N)4(OH-)2,whose special structure is of stretchy octashedron.The X-ray diffraction pattern shows that the copper(Ⅱ)-silk sericin complex has an amophous structure of random coil.
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发布时间：2021-03-19 - 摘要：Poly(ethylene oxide)macromonomer was prepared by the reaction of poly(ethylene glycol)and vinyl benzyl chloride with the help of NaH.Through dispersion copolymerization of poly(ethylene oxide)macromonomer and styrene carried out in the media of ethanol/water, amphiphilic microspheres ranging from 0.5～1.5μm were prepared. The resulted amphiphilic microspheres were characterized by scanning electron microscope, IR etc, and the formation of copolymer was confirmed by IR spectra of amphiphilic microspheres and solubility of amphiphilic microspheres in the media of benzene.The factors which affected the diameter and diameter distribution of microspheres,including concentration of monomer,concentration of dispersant and composition of the media of reaction,were systematically investigated.
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发布时间：2021-03-19 - 摘要：The hydroxyl terminated polyethers, though industrially widely available,have not been used as tougheners for amine cured epoxy resins. The Bu2SnO-Bu3PO4 condensate Sn P6700 was used to catalyze the addition of hydroxyl group to epoxy group. In the presence of this catalyst hydroxyl terminated poly(tetramethylene glycols)(PTMG) were used directly as the toughener for the epoxy resin with 4,4′-diamino diphenyl sulfone as the curing agent. PTMG was first reacted with the epoxy resin to form block copolymers.Micro-phase separation took place upon curing.The particle size of the dispersed phase was in the range of 0.4 to 1.4μm when the molecular weight was in the range of 700 to 2000,which was favorable to the toughening.When ca. 5 phr of PTMG was used as modifier,the toughness of the cured resin was improved greatly with a slight lowering of Tg and modulus.
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发布时间：2021-03-19 - 摘要：The compatibility of components, melting and crystallization behavior as well as degradations of blends for maleated LLDPE(MPE)/poly(ε-caprolactone)-poly(oxyethylene) copolymer(PCE)have been investigated by vibrating reed, DSC and FTIR. The degradations are characterized by the retention of tensile properties.The results show that the maleation reaction occurs at the methyl end group of the short-chain branching of LLDPE, resulting hydrogen interaction between maleic anhydride and hydroxyl group of PCE.This type of the interaction causes a partial compatibility between the blend components,as indicated by an inward shifting of the glass transition of PCE and βtransition of MPE.Introduction of ethyl-acrylic acid copolymer(EAA)in the blends further depresses the melting point,reduces the melting enthalpy and enhances the compatibility of components.The photo- and hydrolytic degradations of MPE/EAA/PCE blends increase with PCE content.The rate of a combination of the photo-hydrolytic degradation is more rapid than that of the individual degradations of photo- or hydrolytic nature.
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发布时间：2021-03-19 - 摘要：In literatures montmorillonite’s organic modification usually use one-step intercalation method, we developed a two-step intercalation method by using two different organic salts continuously．After eomparing the effects of one-step method and two-step method,we found that the effect of two-step intercalation method was much better than that of one-step method．The nanocomposites were prepared bysuspension polymerization of methyl methacrylate(MMA)containing intercalated montmorillonite,and the resuIts of their FT-IR,XRD and SEM studies proved that the montmorillonite was effectively swollen or exfoliated Adding montmorillonite could affect the process of suspension polymerization．We found that the conversion of monomer was lowered,the shape of polymer granules was changed to be irregular,and granules’diameter was enlarged．DSC,solvency experiment and strain experiment showed that adding montmorillonite may improve the properties of PMMA because of polymer’s cross-linking by montmorillonite．The best weight content of montmorillonite was about 3％．
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发布时间：2021-03-19 - 摘要：The structure changes of the industrial yarn of poly(ethylene terephthalate)(PET)of 1455dTex／ 110f under the tension of 0.3N and at the temperature range of 375～494K were characterized by WAXD, density gradient method,sonic velocity measurements,and DSC The shrinkage could be divided into two different processes characterized by different relaxation times and final shrinkage amounts The molecular mechanism for the first process,the fast and dominant one,mainly was the disorientation of the extended segments in the amorphous region,which can be proved by the change of orientation function of the amorphous region(fam)with shrinkage time at different temperatures．More meaningful thing is that the shape and change tendencies of fam and relative length(lt)with shrinkage time are very similar The second slow one was resulted from the restructuring of the crystalline region,which included the rapid growth of the erystallites,the formation of new imperfect crystals and the reorganization of existed crystals during the whole shriknage process．The changes of crystalline regions became fast with the temperature rising and consequently their effect of restriction of the disorientation of the amorphous region became more obvious．However,the orientation function of crystalline regions keeps unchanged almost during the thermal shrinkage process It should be indicated that the structure changes of amorphous and crystalline regions are not independently．Each process proceeds and competes each other during the thermal shriknage The contribution of both processes to the shrinkage mainly depends on the temperature and time The study of structure change of PET yarn during thermal shrinkage provides an important idea of developing more perfect crystalline regions to limit the thermal shrinkage due to the disorientation in amorphous regions PET yarns with strength of 7cN／dTex,modulus of 4．4cN／dTex at 5％elongation and thermal shrinkage of 3.5％have been successfully obtained.
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发布时间：2021-03-19 - 摘要：HDPE and PET are known to be imcompatible polymers．To improve the properties of HDPE／PET blends,ethylene vinyl acetate copolymer(EVA) was used as a compatibilizer in this system Owing to chemical structure similarities,EVA displays some miscibility with HDPE．On the other hand,ester groups of EVA can react with the polyester macromolecules and fotin PET-EVA copolymers as compatibilizers in situ during reactive processing through twin screw extruder by transesterification reactions in the presence of catalyst-organometallic compound．The results of 1H-NMR show that grafted or co-crosslinked eopolymers PET-EVA was generated at the interface of blends by transesterification during processing operation with organometallic compound,which enhanced the compatibilization of HDPE／PET blends Transesterification reaction between PET and EVA led to a grafted copolymer mainly．
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发布时间：2021-03-19 - 摘要：The orientational order of a liquid crystalline(LC)system is in favor of the alignment of nonlinear optical(NLO)units．If a NLO unit is also a LC unit,the resulted liquid crystalline NLO polymer may possess a higher orientational order and therefore promote the nonlinear optical sensibility A polymalonate side chain liquid crystalline(LC) polymer with a nonlinear optical nitro azobenzene type mesogenic unit has been synthesized by melt polycondensation,which was characterized by FTIR and 1H-NMR．The thermal transition temperatures and LC properties of the polymer were determined by DSC,polarized optical microscope(POM) and WAXD．A typical smectic focal conic texture was observed under POM and two small sharp WAXD peaks corresponrling to Bragg’s spacings 2.74nm and 1.35nm appeared in the smecticphase．Moreover,spin-coating films of the polymer through corona poling possessed an orientational order parameter ∮=0.33 calculated from UV measurements．But light scattering resulted from the crystallization of the polymer reduced the transparency of the polymer film and some small sharp peaks appeared in the UV spectra.
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发布时间：2021-03-19 - 摘要：The thermal-oxidative degrading regulation of blends containing starch,polyethylene and additives which is made up of combination of Fe3+ -oleic acid at simulating composting emperature(70℃) was stdied．Sample films were made by conventional extrusion blowing．The additives and starch were introduced into the LDPE matrix in the form of masterbatchs in the amount of 10％(W／W) and 60％(W／W),respectively．Samples were put into two different degrading environments,a certain number of filmswere taken out after an interval of ten days for testing．The mechanical properties,viscosity-average molecular weight and hydroperoxide concentration of the samples in the matrix were measured Moreover,the superficial conformation and crystal capability of the aged samples were also characterized by SEM and XRD．It was showed that the adopted additives could catalyze the degradation of PE efficiently．Besides,it was found that though the concentration of O2 affected very much the degrading behavior of PE,the catalyzing efficiency of some additives,such as F5,with high content of Fe3+ was almost unaffected under low O2 concentrations So it was more suitable for initiating degradation of PE at real composting environment The degrading mechanism of PE matrix was deduced according to the experimental results The kinetics of hydroperoxide formation corresponded to an exponential law as claimed in the 1iterature．The Curve of hydroperoxide accumulation well conformed to a quadratic law in the early stage,when the progress deviated from the induction period,passed the maximum rate,and reached the limit concentration [POOH]∞ at deceleration
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发布时间：2021-03-19 - 摘要：Dynamic viscoelasticity of curvielan,a novel gel-forming exopolysaccharide produced by soil bacterium Alcaligenes sp.Q9415 was studied.Over the angular frequency (ω) range 0.01～100rad·s-1,the storage modulus ( G′) of 1.4% (W/W) curvielan gels was much higher than its loss modulus (G″) and less dependent on frequency which showed that curvielan had fine elasticity.0.5% was close to the threshold concentration needed for gelation.Curvielan was dispersible in cold water to form weak gel which could become much strong viscoelastic gel at about 90℃ for 10min.Continuous heating at high temperature and freezing-thawing treatment damaged the network of curvielan gel.Similar results were observed for curvielan gels prepared under pH3 and 10.Addition of 1%～18% NaCl,6% KCl,CaCl2,MgCl2,Zncl2and 20% sucrose decreased the G' of 1% curvielan gel at low frequency and increased G″ over the frequency range 0.01～100rad·s-1 which indicated that the formation of elastic network was hindered.However,addition of 6% AlCl3 of FeCl3 made total loss of viscoelasticity of the 1% urvielan system.
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发布时间：2021-03-19 - 摘要：Two stilbene-containing polyethers(PSEG,PSV) were synthesized and their thermotropic liquid crystalline behavior was investigated. The respective backbone polymers,poly(glycidyl 2-chloroethyl ether),P(GCE),and poly(glycidyl 2-chloroethyl ether)-co-4-hydroxybutyl vinyl ether),P(GCE-co-HBVE),were prepared by cationic polymerization and photo copolymerization respectively.Liquid crystal polyether PSEG,PSV were synthesized through the macromolecular reaction of P(GCE) and P(GCE-co-HBVE) with 4-nitro-4′-hydroxy stilbene (NHS) respectively.The chemical structures and chromophore contents of these polyethers were characterized by means of FTIR,1H-NMR and EA. The phase transition temperature,texture structure,thermal stability and phase behavior were investigated by POM,DSC,TGA and WAXD.The results showed that these polyethers were nematic bitropic liquid crystals with low and wide phase transition temperatures,as well as good thermal stability.
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发布时间：2021-03-19
Research Article
- 摘要：The influence of irradiation parameters,such as the irradiation time,temperature and the acrylate functionality of monomers on the infrared laser induced photopolymerization were investigated in this paper A novel cationic cyanine dye-borate complex,1,3,3,1′,3′,3′-hexamethyl-ll-chloro-10,12-propylene-tricarbocyanine triphenylbutylborate,was employed as the photoinitiator It had maximum absorption wavelength λmax at 780 nm in 2-butanone with the maximum molar extinction coefficient εmax of 1.4×105 L·mol-1 cm-1 which matched well with the emitting wavelength,796 nm,of the adopted infrared laser diode With poly(vinyl alcohol)(PVA)as oxygen barrier layer,photopolymerization system containing trihydroxymethylpropanetriacrylate(TMPTA),binder and photoinitiator was cured by 2 min of infrared laser irradiation Modest improvement of the double-bond conversion could be achieved by increasing the irradiation time or temperature．Furthermore．it was found that the monomer with diacrylate functionality had higher double bond conversion than that with triacrylate functionality under the same irradiation conditions．Double-bond conversion of 52％could be achieved for diacrylate monomer phthalic diglycol diacrylate(PDDA)compared with 25% for triacrylate monomer TMPTA．
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发布时间：2021-03-19 - 摘要：The effects of esterification with stearic acid on the crystallizing behavior,thermal stability and resistance to water of polyvinyl alcohol(PVA) were studied by using IR, WAXD, DSC, TG and water resistance test.The results show that the esterification of PVA with stearic acid could take place in the presence of dibutyltin dilaurate at 128℃.—OOC(CH2)16CH3 groups are introduced into PVA molecular chains during esterification.With increasing the reaction time, the thermal stability and water resistance of PVA are improved.However,the crystallinity and melting temperature of PVA are decreased.As reaction time exceeds 16h,the crystalline structure of PVA disappears according to WAXD and DSC curves.The initial decomposition temperature after esterification is over 200℃,much higher than that of PVA.These results suggest a method for improving the thermal stability and water resistance of PVA.
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发布时间：2021-03-19 - 摘要：Polyphenylene sulfide (PPS)/polyamide 6 (PA6) blends were prepared by different methods including melting-,powder- and powder-solution-blendings.Effect of interface interaction on the crystallization behavior of PPS and PA6 componens in these blends were investigated by components differential scanning calorimetry under nonisothermal conditions.The results indicate that the crystallization temperatures for PPS are shifted to a greater extent than those for PA6 in the blends.The PPS and PA6 both crystallize at higher temperatures as a result of blending.The crystallization temperatures of PPS in its blends are always higher than that of pure PPS and are independent of the method of preparation.The order of increase in the crystallization temperatures of PPS is melt-blends>powder-solution-blends>powder-blends.The PPS crystallization peak becomes narrower and the crystallization temperature shifts to a higher temperature,suggesting a faster rate of crystallization as a result of blending with PA6. This enhancement in nucleation of PPS could be attributed to the possible effect of interfacial ineraction between the component polymers in inducing heterogeneous nucleation.
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发布时间：2021-03-19 - 摘要：The intercalate and exfoliate actions of BHET or PEG for montmorillonite are discussed.BHET(ethylene glycol terephthalate) can be absorbed and intercalated between layers of montmorillonite, not only at high temperature, but also normal temperture.Especially at temperatures,30～40℃ over the melt temperature,more BHET are absorbed by montmorillonite.When the content of montmorillonite is less than 10% in its mixture with BHET the stack layers of montmorillonite can be exfoliated into single layers.But when the content of montmorillonite is more than 10% a few exfoliated layers combined into more layers.Montmorillonites can also absorb PEG,but in this case only the layer distances are increased,no layer exfoliation is observed.Between the layers one to three layers of PEG molecules can be adsorbed.So that,there are respectively three peake d=4.4,3.4 and 1.8nm in WAXD curves.When the content of nontmorillonite is more than 10% there is only one layer distance d=1.8nm.
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发布时间：2021-03-19 - 摘要：Pyrene was used as a fluoresecent probe to investigate the polarity and stability of the micelle of anionic aqueous polyurethane dispersion (AAPUD).Results indicated that the micelle is non-polar or weak polar,and the polarity is greatly dependent on the hydrophilicity of the main chain of polyurethane and the pH value of the medium.The polarized value of the polarized fluorescent of pyrene in the AAPUD was measured,and the results show that the stability of the micelle could be characterized by the polarized value.
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发布时间：2021-03-19 - 摘要：The resistivity of the conductive composite varies as a function of the volume fraction of the conductive material．Considerable experimental and theoretical work has been done to examine how the volume fractions and the morphology of the components affect the electrical behavior of the composite materials The generalized effective medium(GEM) equation gives the complete information on how the volume fraction of components may affect the medium conductivity by taking into an account the intrinsic conductivities and geometries of both components and also their arrangement and orientation in the applied electric fields．In this paper the electrical percolation phenomenon in CB／HDPE composite influenced by eros,slinking under different irradiation doses and different ambient temperatures has been investigated．The experimental data regarding the dependence of conductivity on the volume fraction of CB were fitted into the GEM equation．The parameters in the GEM equation,corresponding to the dispersion characters of CB in HDPE matrix,were determined through the computer fitting．The CB particles aggregated constructing a three-dimensional conducting network along the electrical current direction．The polymer matrix,however,is statistically vertical to electrical current direction,hindering conductive particles from contacting each other The higher the irradiation dose or the ambient temperature,the more serious the hindrance．The electrical conductivity of FIDPE composites filled with high-structure CB particles is dominated by percolation mechanism based on a particle-touching model,while crosslinking or ambient temperature increasing causes a larger gap between the conductive particles and makes the conductivity more affectd by tunneling mechanism.
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发布时间：2021-03-19 - 摘要：The DR-PPA polyelectrolyte complex was formed via the interaction of diazoresin(DR) and polyphosphoric acid(PPA) in aqueous solution The DR-PPA complex does not dissolve in water but dissolves considerably in sodium dodecyl sulfate(SDS)aqueous solution．The solubility of DR-PPA in 0.05．0.10,0.15 mol／L SDS aqueous solution(100 mL) was determined at 20℃ to be 0.25,1.10 and 1.80 grespectively The DR-PPA／SDS film on a substrate(modified PET film or anodized AI plate) is photosensitive and can produce an image under the exposure of UV light through a photographic film．The Dhotodecomposition of DR-PPA in 0.15 mol／L SDS aqueous solution or in its solid film was carried OUt and confirmed to be．both in solution and in film,in accordance with the first order reaction in kinetics An ultra-thin multilayer film from DR and PPA has been prepared by self-assembly technique．It was verified that the self-assembly process progresses smoothly with an absorbance increasing of ～0.02 per DR-PPA layer at 370 am．The multilayer film is also photosensitive and its decomposition is also in agreement well with first order reaction．Under UV irradiation the ionic bond both in the coating and in self-assembly films converts to covalent bond．As a result the dissolution behavior of the DR-PPA film changes dramatically i.e. from soluble in SDS aqueous solution to insoluble because the crosslinking nature of the film changes from ionicbefore irradiation to covalent after irradiation．
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发布时间：2021-03-19
Research Bulletin
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