最新刊期
卷 ， 期 5 ， 1999
- 摘要：The non isothermal behaviors for maleic anhydride graft polypropylene and its Na+, Mn2+, Ca2+ ionomers under different cooling rates have been studied by DSC. Theanalysis of exothermic peaks has been done in terms of peak temperature ( Tmax) ,startingcrystallization temperature( To) ,initialslope (Si) and width of half height (Δw) . Avramiequation and a combination of Avrami-Ozawa method were used to analyzee the non isothermalcrystallization kinetics. Allionomers had higher rate of nucleation, characterized by the higher values of Si,overall rate of crystallization, characterized by the higher values of (Tmax-To),and narrower crystallite size distribution,characterized by the lower values of Δw,than those of pure PP and PP-gg-MAH.The plots of Si versus.temperature (To or Tmax) are more accurate and valudble than the plots vs. cooling rate at evaluating the crystallization characteristic of samples. The fact that all samples had Avrami exponents in arange of 2.5～2.8 implied the mode of PP crystallization was not changed by varied cooling rates by the solid graft modification.
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发布时间：2021-03-19 - 摘要：Anew kind of monomersincluding aromaticspirodilactone———5 ,5′-carboxy-7 ,7′-dioxo-2 ,2′-spirobi(benzo-[c]tetrahydrofuran) is synthesized from m-xylene and paraformaldehyde. It is converted to a series of polyamides and polyesters by means of low temperature solution polycondensation and interfacial polycondensation . NMR and I Rspectra ,solubility , mechanicaland thermal properties of allthese polymers areinvestigated . The polymers have high glass transition temperatures and good thermal oxidative properties. All polyamides have high viscosity and good solubility in strong polar organic solvent, flexible and tough films possessing good tensile properties.
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发布时间：2021-03-19 - 摘要：In a previous study ,the melt grafting of glycidal methacrylate( GMA) and styrene(St) onto polypropylene(PP) was carried out. The multi monomers melt grafted PP, PP-g-(GMA-co-St) was used as a compatibilizer of PA6/ PP blendsin this study . The addition of PP-g-(GMA-co-St) markedly improved the mechanical properties of the incompatibilized PA6/PP(PA6 content 70% ) ,particularly in the tensile strength of the blends . There arealso significant changes in glass transition temperature (Tg) for the blends characterized by DSC analysis, implying excellent compatibility between PA6 and PP with the addition of the PP-g-(GMA-co-St). Different blend morphologies were observed by SEM and TEM accordi9ng to the content of PP-g-(GMA-co-St) used.A special novel microphase separated structure in the PA6/PP-g-(GMA-co-St) blends were observed. It should be bud to the formation of PP-PA6 copolymer by chemical reactions occurred between GMA in PP-g-(GMA-co-St) and the terminal amino or carboxylic groups of PA6 during the melt mixing. The formation of PP-PA6 copolymer is also characterized by FTIR.
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发布时间：2021-03-19 - 摘要：The emulsifier free emulsion copolymerization of styrene (St) and methylmethacrylate (MMA) in the presence of functional monomer acrylic acid (AA) was carriedout in batch process. Effects of concentration of functional monomer AA, initiatorconcentration [APS] and polymerization temperature T on the kinetics of thecopolymerizatuion were investigated . Model function of cumulative conversion vs .reactiontime———Integrated Gam ma Function was built up ,and was empolyed to fitthe samples of cumulative conversion versus reaction time. The maximum polymerization rate (MV),average polymerization rate (AV)in the steady stage,average nucleation rate (NV) and the corresponding cumulative conversions at moment of nucleation stage ceasing and at the steady stage completing were estimated by calculating extremums and inflexions of it's fitted Gamma Function. Whereafter, the polmerization rate versus each single polymerization parameter was analyzed with non-linear fitting and the related equation was obtained. The results show that the fitting error is very small and both the nucleation rate and polymerization rate increase with increasing [AA],[APS] and polymerization temperature T.Among these reaction parameters,[APS] plays a predominant role in the polymerization. The cumulative conversion is within 15% when the nucleation stage ceases.
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发布时间：2021-03-19 - 摘要：A fume silica supported poly-4-oxa-6,7-epithioheptylsiloxane palladium (0 )complex was synthesized from γ-(2 ,3-epithiopropoxy) propyltrimethoxysilane and fumesilica via hydrolysis,followed by treatment with palladium chloride in acetone and then thereduction with hydrazine hydrate in ethanol. It was found that the title complex is anefficient catalystfor Heck arylation ofstyrene and acrylic acid . When aryliodides were usedas arylating reagents, the corresponding trans coupling products were obtained in high yields. This polymeric palladium (O) catalyst is stable to air and can be reused without noticeabil loss of activity. Hence this paper presents a simple and practical stereo-selective synthetic method for unsymmetrical trans-stilbenes and substituted trans-cinnamic acids.
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发布时间：2021-03-19 - 摘要：The miscibility and complexation behavior of poly(styrene-co-4-vinylphenol)(STVPh) and poly(styrene-co-4-vinylpyridine)(STVPy) in bulk have been investigated bydifferential scanning calorimetry (DSC) combined with physical aging as well as non radiative energy transfer (NRET) fluorospectroscopy . It has been found that when thehydroxylcontent in STVPh reaches 3 ,6 ,9 mol% ,the miscibility of STVPh with STVPycan be achieved which contains 25 ,50 ,75 mol% vinylpyridine unit (VPy) respectively. It is noticeable that when the hydroxyl content is further increased,complex formation between the components occurs. An apparent casting solvent effect on both moscibility and complenxation has been also discussed.
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发布时间：2021-03-19 - 摘要：Synthesis and characterization of high conductivity polyaniline/clay hybridnanocomposite with extended chain conformation are presented in this paper. The conductiveemevaldine saltform of polyanilineisinserted into the galleries of montmorilloniteto producethe hybrid with high conductivity . The properties of the hybrid are characterized by X Raydiffraction ( XRD), FT-IR,conductivity measurement,qualitative and quantitative analysis ofelectron and opticalspectra ,theresultsshow that what we obtained is really a nanocomposite and over 90% polyaniline chain is inserted between the layers. In the nanocomposite polyaniline exists in single chains with extended-chain conformation owing ot the confined environment in the nanometer size gallery. Monitoring the polymerization process by electron and optical spectra it was found that the polymerization is a diffusion-limited process.
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发布时间：2021-03-19 - 摘要：The crystalliztation , dynamic mechanical properties, tensile properties andmorphology features of polyamidel 1010( PA1010) blends with the high impact polystyrere( HIPS) and maleic anhydride (MA) grafted HIPS(HIPS-g-MA) were examined at a widecomposition range . By comparison the PA1010/ HIPS-g-MA and PA1010/HIPS binaryblends ,it wasfoundthatthe size ofthe domains of HIPS-g-M Awas much smallerthan thatof HIPS at the same compositions. It was found that the mechanical properties of PA1010/HIPS-g-MA blends were obviously higher than those of PA1010/HIPS blends. When the content of PA1010 is more than 50wt% in the blends, the crystallization temperatures, Tcs, of PA1010 increase with increasing the content of HIPS-g-MA. On the other hand, when the content of PA1010 in the blends is less than 35wt% the fraction crystallization is observed. The same result is not obtained for the blends of PA1010/HIPS. These behaviors could be attributed to the chemical interactions between the two components and good dispersion in PA1010/HIPS-g-MA blends.
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发布时间：2021-03-19 - 摘要：Diglycidyl dicyclopentadienedicarboxylic acid ester(DGDCA) was used as acrosslinking monomer and was copolymerized with epoxide monomers, such asepichlorohydrin(ECH) ,by ring opening polymerization catalyzed by alkylaluminum system . The effects of polymerization procedure,feed ratio and reaction conditions on the monomerconversion and structure of the copolymer were studied in detail. It has been found that thecatalytic activity of AlBu3H3-PO4-NEt3 system was higher than Ali Bu3-acac-EtOEt-H2O catalyst both in homopolymerization of ECH and in copolymerization of DGDCA/ECH, the properties of reaction media have influence both on molecular weight of polymer and on the conversion of coplymerized monomer, such as in homopolymerization of ECH,the [η] of the polymer have reached 4.9(dL/g).And the conversion was lower down to 76.3%. In addition the feeding order of monomer and catalyst were almost haven't influence on conversion and composition of copolymer, when the weight ration of comonomer DGDCA/ECH was controlled in 31～40,the conversion of most feeding order were higher than 90% in cyclohexane as diluent and when EO or PO was used instead of ECH in copolymerization with DGDCA similar results and rules as above has been obtained. The structure and thermally reversible covalent crosslinking properties of the obtained copolymers were confirmed by IR analysis and the tests of reacting solubility,DSC and pyrofluxibility.
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发布时间：2021-03-19 - 摘要：Photopolymerization of styrene ( St ) with benzyl N, N-diethyldithio carbamylacetate( BzDCA) was studied.It was found that the number-average molecularweight(Mn)of polystyrene and the conversion increase with the increasing ofreaction time ,respectively. The conversion also increased with the concentration of BzDCA,while Mndecreased with the increasing of BzDCAconcentration . When [ St]/[BzDCA] = 874 ,the Mn of PS had alinear relationship with the conversion ,and agreed well with that calculated from the initial St and BzDCA concentrations and the conversions. The mechanism of the polymerization was proposed and the polymerization proceeded via a "living" radical polymerization mechanism. Under Uv irradiation, BzDCA dissociates into two kinds of radicals:carbon-Centered radical and sulfur-centered radical.The primary carbon-centered radical can initiate monomer polymerization and the sulfur-centered radical can reversibly terminate with propagating radical and form a diethyldithiocarbamate(DC) end group.
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发布时间：2021-03-19 - 摘要：Methanesulfonic acid method was used to prepare five acylated chitins. Exceptheptanoyl chitin , four of them ,i.e.acetyl chitin ,propionyl chitin ,butyryl chitin andhexanoyl chitin ,had high degree of substitution(from 1.5 to 2.0)and exhibited lyotropicliquid crystalline behavior and cholesteric phase . Asthelength oftheside chain increased thecritical concentration (W/ W)somewhat increased from 0.21 to 0.26 because the chainrigidity dropped . The criticalconcentration valuesofallthefour derivatives were much higher than that of chitin (0.12) due to the decrease of intramolecular hydrogen bonds. The four acylated chitin can form typical banded texture after being sheared. There minimum concentrations to form banded texture of them were evidently different,varied from 0.25 (for acetyl chitin)to 0.37 (for hexanoyl chitin).These results further indicated that liquid crystallinity decreased while the length of flexible side substituents increased.
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发布时间：2021-03-19 - 摘要：The behavior of multiple block copolymer chains with two kinds of chemicalcomponentsin dilute solutions has been studied by Monte Carlo method . Addressed here isan exploration that various block sequencelengths affectthe nature ofthecopolymers. In thissimulation ,the chains are generated in the way of self avoiding walking . The solubility ,theshape of chain topology and the topological distribution of chemically different blocks of thecopolymers were respectively examined . Obtained results show that in the same solvent the length of the block sequence influences remarkably the solubility of the copolymers. The solubility does not change monotonously with the block length. The shape of chain topolgy exhibited the same behavior. The difference of the interaction between the two different blocks results in the dependence of the solubility and the chain shape on the block sequencelength.
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发布时间：2021-03-19 - 摘要：A new kind of amphiphilic random copolymers has been synthesized by radicalcopolymerization of quaternary alkyl salts of dimethylaminoethyl methacrylate(QASDMAEMA) with styrene (St) in solution ,in which the salts are butyl bromide salt(MABB) and ethyl bromidesalt (MAEB) ,respectively. Variousexperimental parametersofthe copolymerization andthe solubility ofcopolymers were studiedin detail. The structure ofcopolymers was determined by the spectra of IR,1H-NMR and 13C-NMR, which are perfectly consistent with the expected macro-molecular structure of the random copolymer with both hydrophobic and hydrophilic chain units.Finally,monomer reactivity ratios of MAABB/St and MAEB/St were obtained, rMABB=0.44,rSt=0.15;rMAEB=0.66,rSt=0.36,using YBR method.
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发布时间：2021-03-19 - 摘要：The living carbocationic polymerization of isobutylene(IB) has been investigatedby the 2-chloro-2 ,4-,4-trimethylpentane (TMPCl)/TiCl4 initiating system in the presence of N, N-dimethylaniline (DMAB) and Et3Nas electron pair donors (EDs) by use ofthe mixedsolvent dichloromethane hexane (40/60 V/ V)/ at -80℃under conventional laboratoryconditions. It is demonstrated that living polymerization can be achieved when theconcentration of electron pair donors such as DMAB or Et3N is higher than that of trace water in the polymerization system,and that polymers with narrow moleculat weightdistribution can be obtained. The rate of polymerization is also reduced because of adding EDs which indicates that stabler active centers are formed.
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发布时间：2021-03-19 - 摘要：1,4-Bis[4-(2-amino-4-phenyl)thiazoleyl] benzene wasfirstsynthesized from 1 ,4-bis(benzeneacetyl) benzene. The synthetic routes are shown in thefollowing equations : The structure of 1,4-bis[4-(2-amino-4-phenyl)thiazoleyl]benzene was confirmed by IR,1H-NMR,13C-NMR and elementalanalysis. The novelpolyimide(TIB) and copolyimide(TIBO)containing thiazole ring were prepared by reacting 1 ,4-bis[4-(2-amino-5-phenyl)thiazoleyl]benzene or/and 4 ,4′-diaminodiphenyl ether with 3 ,3′,4 ,4′-benzophenone tetracarboxylic dianhdride. Their films exhibited good thermal oxidative stability. The decomposition temperatures in air and in nitrogen were 499, 488℃ (for polyimide) and 510,498℃copolyimide, respectively. The copolyimide (TIBO) film was converted into electrical conductor by pyrolysis at 1200℃ was as high as 64S/m and is was very stable in air.
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发布时间：2021-03-19 - 摘要：The colloidal dispersion gels (CDG) were prepared by low concentration partiallyhydrolyzed polyacrylamide with different molecular weights and aluminum citrate. Theproperties of CDG were investigated by the Oswald capillary viscometer,ultrafine sizeanalyzer and theflow experiment. The resultsshowedthatthe viscosity of CDG islowerthanthat of hydrolyzed polyacrylamide (HPAM) and the viscosity of CDG decreases withincreasing the reaction time. The particle diameter of CDG with HPAM molecular weights of 4×106and 1.4×107 was determined to be 460 and 510 nm, respectively. The flow resistance of CDG, which generally increased with increasing HPAM molecular weights and concentration, is much larger than that of HPAM solutions in the core. The flow resistance of the CDG in lower-permeability core was increased more quick than that of the CDG in higher-permeability core. The flow resistance of CDG in the core was associated with the moleculare weight and concentration of HPAM and the permeability of the core. CDG is able to increase the flow resistance in the core effectively.
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发布时间：2021-03-19
Research Article
- 摘要：The quantitative relation between notched impact strength and fractured surfaceroughness of polymer materials at different testing temperature was investigated withdifferent polymer. The resultsshow thatthe notched impactstrength σi of polymer materialsincreasedlinearly with theincrease offractured surface roughness parameter Rs in the case ofbrittle fracture atlowertesting temperature . Butthe variation ofimpact strength depends onboth Rs and the plastic deformation area in the case of ductile fracture at higher testing temperature.The relation between σi and Rs at higher testing temperature could be divided into three models according to different polymer materials and ther fracture mechanism.
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发布时间：2021-03-19 - 摘要：The structure and properties of peroxide crosslinked LDPE and silane crosslinked LDPE were comparaed in gel content,equilibrium swelling ratio and high temperaturemodulus. The crosslinking densities of LDPE vulcanizates were measured by the method ofhigh temperature modulus. When the two kinds of crosslinking LDPE’s gel contents aresimilar,the crosslinked densities of peroxide crosslinking LDPE are obviously smaller thanthose of silane crosslinked LDPE. Using equilibrium swelling ratio or crosslinked density to characterize the crosslinking degree of LDPE vulcanizates is more appropriate than usng gel content. The Huggins parameter of LDPE/boiling benzene system was also determined as 0.30.
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发布时间：2021-03-19 - 摘要：Spheric polycaprolactone (PCL) microparticles were prepared by PCL polymerwith an emulsification-solvent evaporation technique . Effects of various stabilizers,such asgelatin ,hydrophobically modified polyacrylamide derivative (PAM) and poly(vinyl alcohol)(PVA) on the morphology and particle size distribution of the PCL microparticles werestudied. The degradation behaviors of the PCL microparticles were compared with andwithoutlipase under pH7.4 at 37±1℃. Theresultsshowed thatin the case of using gelatin as a stabilizer the degradation rate of the PCL microparticles was accelerated in the presence of enzyme—lipase was evidenced by SEM and GPC measurements. On the other hand,according to SEM,interference contrast microscopy and X-ray diffraction techniques,is was evidenced that the degradation of the PCL microparticles started in the amorphous area of the PCL microparticles.
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发布时间：2021-03-19 - 摘要：Five samples of perfluoroheptyl end capped polyacrylic acid (FPAA) having ahigh surface activity were prepared by free radicalpolymerization ofacrylicacid . Theinitiatorwas perfluorooctanoyl peroxide which produced the free radicalof heptyl at 45℃. The yieldsof FPAA were in the range of 10% to 25% . The weight average molecular weights were 2.62×104 to 7.99×104 and the polydispersity indexes were 1.97 to 5.64 ,depending on theconcentration of the initiator in the monomer. The surface tension was about 15mN/m at 30℃ for the aqueous solution of FPAA with the weight-average molecular weight 2.62×104 in the concentration of about 0.01g/mL.The molecular areas of FPAA at the air-water interface under the condition of critical micelle concentration were 3.2 to4.6nm2,which are obviously larger than the area per molecule of perfluorooctanoic acid (2.14nm2) and much smaller than that of ordinary polyacrylic acid (83.4nm2).It means that the polymer molecules in the surface adsorbed layer form the brush structure because of the special effect of the perfluoroalkyl groups at the chain ends.
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发布时间：2021-03-19 - 摘要：The biodegradation behavior in vitro and in vivo of polycaprolactone poly (ethylene oxide) block copolymers (PCE) has been reported in detail. Photodegradation testof PCE was performed by exposure to UV light. The mechanical properties and the inherentviscosity of PCE samples which are subjected to photodegradation were determined . Thephotodegradation rate of PCE was much more faster than its hydrolysis rate and wasincreased with increasing poly (ethylene oxide) content. The experimental results also indicated that the pure poly (ethylene oxide)(PEO) can not be photodegraded alone. Amechanism for the photodegradation of PCE copolymers was proposed:the carbonyl groups in PCL segments catalyze the breakage of the PEO chains by a series of UV initiated free radical reactions. When the free radicals induce the degradation of PEO segments in PCE, the photodegradation of PCE mainly occurs in PEO segments.
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发布时间：2021-03-19 - 摘要：Afume silica supported poly-γ-(-β-cyanoethylsulfenyl) propylsiloxane palladium(0) complex was synthesized from poly-γ-(-β-cyanoethylsulfenyl) propylsiloxane andpalladium chloridein acetone,followed by reduction with hydrazine hydrate in ethanol. Thestructure ofthis complex wascharacterized by elementalanalysis and XPS. It wasfound thatthe title complex is an efficient catalyst for Heck arylation of acrylamide and butylacrylate . This polymeric palladium(0) catalystis stable to air and can be reused without noticeable loss of activity.Hence this paper presents a simple and practical stereo-selective synthetic method for substituted trans-cinnamamides and trans-butyl cinnamates.
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发布时间：2021-03-19 - 摘要：In order to prepare a polymer solution for making carbon fibre precusor by wetspinning,solution polymerization of acrylonitrile (AN) with itaconic acid (IA) was carriedoutin DMSO using azobisisobutyronitrile (AIBN) asinitiator. The effects of (AN+IA) and AIBN concentration , AN to IA ratio,temperature on conversion rate and molecular weightwere investigated . The polymerization ratein DMSO was 2.6 time as fast at thatin DMF. The copolymers were characterized by IR and NMR analysis.
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发布时间：2021-03-19 - 摘要：The polymerization of tetrahydrofuran (THF) initiated by heteropolyacid H3PW12O40(PW12) in low concentration could be effectively promoted by propylene oxide(PO) . The polymerization conversion reached 50%～60% after a reaction time around 5 h . Wateror butylene glycol was used to controlthe molecular weightofthe productin the rangeof 1000～3000 . The polymerization started upon addition of PO and stopped with completeconsumption of PO,but it would start again when a new portion of PO was added. The average hydroxyl end-group functionality of polyether glycol is close to 2. The ratio of primary and secondary hydroxyl end groups is close to one,and the percentage of the hydroxyl group attached to PO moieties at the polymer chain-ends is higher than 50% of the total hydroxyl end-groups. All the obtained results inferred that THF polymerization promoted by PO proceeded quite similar to that promoted by ethylene oxide,i.e., PO was necessary in the initiation of THF polymerization to start the propagation of chains,and with the complete consumption of PO the propagating chains transformed into dormant species,which can be re-initiated by thd addition of a supplementary portion of PO.
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发布时间：2021-03-19
Research Bulletin
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