最新刊期
卷 ， 期 1 ， 2004
- 摘要：PLA-b-PEO-b-PLA triblcek copolymers with different compositions were prepared by ring-open polymerization using OH-capped PEO as macminitiatom．The“crew-cut”aggregates of PLA-b-PEO-b-PLA triblock copolymers in aqueous media were fabricated by dropping water into block copulymer solutions in common solvents．The surface morphology and micro-viscoelasticity of aggregates cast on mica sheets from colloids were investigated by scanning probe microscopy(SPM)．It was observed that the micelles with a diameter of about 45 nm were formed and oranized into relatively single layer on mica surface．Interstedly,inhomogeneity of surface modulus appeared as the water of colloids evaporated．The top of aggregates had relatively higher modulus than that of the peripheral parts of aggregates．The changes of environments of aggregates from polar water to unpolar air on mica sheets were suggested to be responsible for the surface modulus inhomogeneity．In addition,the experimental data showed that the sizes of aggregates measured from dynamic light scattering were greatly larger than those from SPM observations．At the sanle time,increasing the initial concentration of copolymers in common solvents resulted in the increase ofaggregate sizes and higher polydispersities.
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发布时间：2021-03-19 - 摘要：Poly (2,2,6,6-tetramethylpiperidinyloxymethaerylate)(PTMA) was synthesized from 4-hydroxy-2,2,6,6-tetramethylpiporidine and methyl methacrylate by the reaction of esterifieation,polymerization and oxidation,and its structure was determined by infrared,ultraviolet-visible,and ESR spectroscopy．Cyclic vohammograms (scan rate：5 mV·s-1) of PTMA showed that the oxidation peak current was equal to the corresponding reduction peak current and the oxidation charge passed during the anodic cycle was almost equal to the reduction charge released during the following cathodic cycle．These results suggest that PTMA possesses exceHent reversibility,and the difference of the anodic(Ea.p=3．66 V versus Li/Li*) and athodic(Ec.p=3.58 V) peak potentials is estimated as 80 mV,whichis extremely smaller than that of the other electroactive organic materials in lithium secondary batteries such as disulfide compounds,which leads to the fast electrode reaction rate of PTMA in the charging and discharging processes of the battery．The maximum discharge specific capacity of PTMA is 78.4 mAh·g-1 at a constant discharge current of 0.3 mA(0.2C),the coulombie efficiency is about 95％．In the charging/discharging curves,there are obvious voltage plateaus at 3.65 V and 3.56 V,respectively．The charging/discharging specific capacity of the batteries was almost unchanged after 100 cycles．the decay ratio is about 2％ of the maximum specific capacity of PTMA．PTMA/Li button batteries exhibited an excellent stability in the charging-discharging processes．These results show that PTMA is a promising polyradical cathode materials for lithium secondary batteries．
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发布时间：2021-03-19 - 摘要：The Interactions of benzene,1,2-diehloroethane,acetone,ethanol and ethyl acetate with hydroxyl terminated poly(butadiene/acrylonitrile) based polyurethane (HTBN-PU) and their transports in HTBN-PU were studied by quartz spring method．DSC and FTIR measurements．The non-fickian behavior was found for diffusion of all five solvents in HTBN-PU．Higher solvent vapor pressure led to more obvious non-fickian diffusion．In addition．higher degree of non-fickian diffusion was found for diffusion of 1,2-diehioroethane and ethyl acetate in HTBN-PU,which could be mainly attributed to their polar tems and hydrogen-bending terms of solubility parameters being closer to those of the soft matrix．The benzene and 1,2-dichloroethane had higher solubilities in HTBN-PU than the other three solvents,which could be mainly related to their dispersive terms of solubility parameters being closer to that of the soft matrix．The Florv-Huggins type sorption was found for all the five solvents in HTBN-PU.FTIR results showed that the degree of hydrogen bonding between the urethane groups decreased after slovent uptaking The strength of HTBN-PU after solvent uptaking was mainly determined by the interaction of solvent molecules with the urethane groups．Acetone,ethanol and ethyl acetate could form hydrogen bonds with the urethane groups and therefore msnlts in serious structure destruction and lower strength of HTBN-PU．while the non-polar benzene only slightly influenced its strength．
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发布时间：2021-03-19 - 摘要：A precursor polymer PI-OH was prepared by polycondensation of a diamine monomer with hydroxyl groups(HAB) and a dianhydride monomer(6FDA) in solution．Then cinnamoyl chloride was reacted with the hydroxyl-containing precursor to prepare the photosensitive polymer PI-CI．The photosensitivity of PI-CI was studied by using UV-Vis and FTIR．After being processed by linear polarized polymerization(LPP),the spin-coated films of PJ-CI were used as photo-alignment layers to assemble sandwich-type liquid crystal cells via a capillary action using a nematic liquid crystal 5CB．The observation of polarizing microscopy showed that the PI-CI photo alignment layers had the ability to align LC molecules．The alignment was meliorated with a longer irradiation time．The photosensitive polymer PI-CI synthesized in this work is promising for the application as photo-alignment layers for liquid crystal displays．
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发布时间：2021-03-19 - 摘要：Poly(pentamethylene terephthalate)(PPT) was synthesized by direct esterification polycondensation．The molecular structure of the product polymer was confirmed by 1H-NMR and IR measurements．The intrinsic viscositv of the PPT sample was 0.878 dL/g in a mixture solvent of phenol/tetrachloroethane (1：1 by wt) at 25℃ The crystallization of PPT was analyzed with DSC．Compared with poly(trimethylene terephthlate)(PPT),PPT has lower glass transition temperature (14℃) and melting point(129℃) and higher cold crystallization temperature(85℃)．The kinetic analysis of isothermal crystallization processes showed that the crystallization rate of PPT is lower than that of PET．The crystallization of PPT was heterogeneously nucleated and exhibited threee dimensional growth of sphertdites．Thermogravimetry analysis showed that the decomposition temperature of PPT is 383℃．sanle as that of PPT.
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发布时间：2021-03-19 - 摘要：A novel series of Schiff base type liquid crystalline polymers with crown ether cycle was synthesized for the first time by solution polyeondensation from 4,4'-(alkylene dioyloxy) dibenzaldyhyde(M1),cis-diamino-dibenzo-14-crown-4 (M2) and trans-cis-diamino—dibenzo-14-crown-4 (M3) as the monomers．Monomer M1 has been synthesized by esterifieation reaction of aliphatdiyl chloride and 4-hydroxybenzaldehyde．Monomers M2 and M3 have been synthesized by reduction reaction of cis-dinitrodibenzo-14-crown-4 and trans-dinitrodibenzo-14-crown-4 in the presence of 10％ Pd/C catalyst and hydrazine hydrate．The stereo structures of cis-(trans)-dinitredibenzo-14-crown-4 have been investigated by 1H-NMR,13C-NMR and molecular mechanics theory．It was found that the stereo structures of cis-trans-and dinitrodibenzo-14-crown-4 can be differentiated by 1H-NMR spectrum,approximately belonging to groups C8 and C2,respectively．The molecular weights of the polymers ale not high,and the Mn of the polymers ranges from 13000 to 24000．The monomer structures were identified by using elementary analysis,IR,1H-NMR and MS etc．The properties of polymem were investigated by using GPC,DSC,TG,WAXD and POM．It was found that all the polymers went into liquid-crystal phase when they were heated over their melting temperature (Tm)．The threaded texture and sehlieren texture Van be observed．The glass transition temperature(Tg),melting temperature and isotropization temperature (Ti) change with varlng of the flexible spacer unit in the polymem．All the polymers have hish clearing points and wide mesophase range．The WAXD study illustrated that the polymers of PIb,Pld,PIIb and PIId are liquid crystalline with a nematie phase．A dispersive peak at 2θ near 20°appeared in their WAXD pettems,which is a typical character for quenched nematic liquid crystal polymem．
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发布时间：2021-03-19 - 摘要：The strain and breaking life of polycarbonate under loading of trapezoidal wave shape were investigated for analysing the behavior of polymers under the co-action of cyclic and constant loadings It was found that the fatigue/creep curves under trapezoidal loading are similar to the pure creep curves under constant loading．A strain platform was observed before the break of the samples With increasing the time length of maximum load in each cycle the platform strain value increases,and the break life decreases Under trapezoidal loading the break life of polycarbonate was not simply determined by the contributions of pure creep and pure fatigue,and a term reflecting the co-action of the two demage types should be considered The co-action term is more evident at low temperature A decrease of breaking life of the samples was observed with raising temperature and was explained as the result of increase of individual effects of pure creep or pure fatigue.
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发布时间：2021-03-19 - 摘要：Expanded bed adsorption (EBA) is a novel bioseparation technique,which integrates solid-liquid separation,clarification,and initial purification into a single unit．One of the key points in EBA processes is the choice of a suitable matrix．In this paper,a new type of spherical cellulose-TiO2 composite matrix for EBA was prepared throush the method of water-in-oil suspension thermal regeneration．After activated by epichlorohydrin and attached with diethylamine,the matrix was derivated to function as an anion exchanger for EBA．The effects of the contents of TiO2 and cellulose in matrix on its properties were investigated in details．It was found that TiO2 not only acted as a densifier to impart an increased density to the matrix,but also benefited the activation reaction by epichlorohydrin,giving the activated matrix an epoxy group content of 220 μmol/mL adsorbent．The prepared adsorbent showed a favorable expanded bed performance and could be used with higher linear velocity than that of the commercial Streamline DEAE．The similar protein adsorption behavior both in expanded bed and in packed bed was found with the maximum dynamic adsorption capacity of 48.9 mg bovine serum albumin (BSA)/mL adsorbent．The results indicate the custom-made adsorbent can be applied to the expanded bed adsorption of proteins．
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发布时间：2021-03-19 - 摘要：Four kinds of ancillary ligands-O-C6 H4-X[X(P)=F,Cl,Br,I] were introduced in the design of novel monotitanocene catalysts,Cp*Ti(O-C6H4-X)3．All of the new catalysts show high activity for styrene syndiotactic polymerization．The catalytic activity of the four monotitanocene increased in the order：Cp*Ti(O-C6H4-I)3*-Ti-(O-C6H4-Br)3*Ti(O-C6H4-Cl)3*Ti(O-C6H4-F)3.The addition of triisobutylaluminium(TIBA)to the catalyst system caused a dramatic increase of s-PS yield．At 90℃,MAO/TIBA/Ti=400/200/1(molar ratio),the catalytic efficiency of Cp*Ti(O-C6H4-F)3 is up to 3.46×106g polymer/mol·Ti·10min The polymerization activity of Cp*Ti(O-C6H4-X)3 at MAO/TIBA/Ti=400/200/1(molar ratio) is about 10 times higher than that at MAO/Ti=600(in the absence of TIBA)．The catalytic efficiency of the catalyst and the molecular weight were affected by catalyst composition,monomer concentration and polymerization temperature．The kinetics of styrene syndiotactic polymerization in toluene was also studied．
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发布时间：2021-03-19 - 摘要：Syndiotactic polystyrene(sPS)/montmorillonite nanocomposites were prepared via in site intercalative coordination with Cp*Ti(O-C6H4-F)3/MAO/TiBA catalytic system The montmorillonite modified with 12-aminododecanoic acid can increase catalytic activity on some degree．The nanostructure features were revealded by X-ray diffraction and transmission electmn miemgraphs．It was found that montmoritlonite could be dispersed in the sPS as sheets of 40 nm thich by in-situ syndiotactic polymerization．However．the interaction between the organic material and silicate layer of clay is not thermally stable enoust,to resist the high melt processing temporature of sPS．so nanocomposite could not be achieved by melt mixing directly．The thermal properties of pure sPS and sPS/MTN were investigated．The crystallization temperature and relative crystallinity of the fabricated nanocomposite (3.57％ MTN wt in sPS) increased obviously,it also had good thermal stability,the thermal decomposition temperature was about 50℃ higher than that of the pure syndiotactic polystyrene．
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发布时间：2021-03-19 - 摘要：Orientation of azobenzene units in self-assembled muhilayer films of two side-chain azo polyelectrolytes was investigated by using polarized UV-Vis absorption spectroscopy．Several factors,such as the pH value of dipping solution．the length of flexible spacers and the functional degree of azo chromophores,on the orientation of chromophores in films were investigated．The results showed that the azo chromophores are prior to an in-plane orientation．The factors influencing polyelectrolyte conformation in the self-assembly solutions have significant influences on the orientation degree of azobenzene groups．Increasing the pH value or the length of flexible spacem and decreasing the degree of funetionalization can cause an increase of the ofientation degree of azobenzene chmmophores in the multilayers．Among the three factors,the results showed that the pH value of dipping solution has the most important infltlenee on the orientation of azo chmmophores in self-assembled films because it can directly affect the constellation of azo polyelectrolytes in solution．By adjusting the pH value．the orientation degree of azo chmmophores in self-assembled films can be controlled in a large scale range.
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发布时间：2021-03-19 - 摘要：The adsorption of pyidine and N,N-dimethylaniline by a phenolic resin adsorbent JDW-2 in nonaqueous systems was investigated under static conditions．Experimentol results indicated that the dominating mechanism of adsorption of pyridine and N,N-dimethylaniline by the adsorbent in hexane is a hydrogen bonding sorption process．The equilibrium sorption date for adsorbent JDW-2/pyfidine(or JDW-2/N,N-dimethylaniline) systems in hexane showed good agreement with the Imngmuir isotherm equation The correlation coefficients are larger than 0.99．It implies that the sorption of pyfidine and N,N-dimethylaniline onto the adsorbent in hexane systems is a monomolecular sorption．The influence of ethanol and ethyl acetate concentrations in hexane solutions on the adsorption of pyidine and N,N-dimethylaniline was also studied．
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发布时间：2021-03-19 - 摘要：The adsorption of VB12 was studied by usingthree phenolic resin adsorbents：JDW-1,JDW-2,preparedin the laboratory and a commercial product Duolite S-761 under static and dymanic conditions．The experimental results show that JDW-1 is superior to Duolite S-761 in adsorption of VB12(the saturation adsorption capacity of JDW-1 for VB12 is 84 mg/g dried resin)．A semi-empirical rate equation adequately fits the sorption rate data of VB12 in the initial period．till about 43％～69％ of the equilibrium adsorption．The equilibrium adsorption date for phenolic resin adsorbents/VB12 systems showed good agreement with the Langmuir isotherm equation．The correlation coefficients are larger than 0.99 The adsorption of VB12 therefore is monomolecular adsorption．Experiments of stripping VB12 from JDW-2 resin with 80％ aqueous methoanol showed that 92.20％and 95.93％ of the adsorbed VB12 were removed at 4.2 and 6.4 bed volumes,respectively,(the desorption rate was 1.1 BV/h)．It implies that phenolic resin adsorbents own excellent desorption performance,and it is good to use 80％ aqueous methanol as desorption solvent for stripping VBl2 from JDW-2
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发布时间：2021-03-19 - 摘要：The structure and performance of the blends and blended fibers of PP/GPET、PP/GPET/EVA、PP,GPET/ EVA/PS were studied with SEM,WAXD and dying methods etc．The results indicated that the PP/GPET blends have typical incompatible sea-island biphase structure．The compatibility of PP/GPET blends were impmred with the addition of EVA．The addition of PS led to the increase of the grain size of the polymer blends The dyeing property of blended PP fibers is much higher than that of the pure PP fiber．The blended PP fiber was easilv dyed into dark blue by Kayacelon blue E-EX．
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发布时间：2021-03-19 - 摘要：The effects of polypropylene-g-maleic anhydride(PP-g-MAH) on the structure and performance of PP/polyamide (PA6) blends were studied by using DSC,SEM,and melt-spinning,etc．The results indicated that PP/PA6 blends have typical incompatible sea-island bi-phase structure：the compatibility of PP,PA6 blends was improved with the addition of the grafted copolymer PP-g-MAH．PP and PA6 crystallized separately in the bulk blends．instead of forming co-crystallization or new crystalline forms．Both the crystal growth rate and nucleation rate of the blends were decreased,due to the in-situ reaction-compatibilization of PP-g-MAH with PA6．The spinnability of the PP/PA6 blends was obviously improved due to the addition of eompatibilizer．
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发布时间：2021-03-19 - 摘要：An unambiguous assignment of the main 1H and 13C-NMR resonances of nylon 11 in trifluoroacetic acid solutions has been carried out by using a combination of 1D and 2D NMR beteronuclear techniques(HMQC)．The spin-spin relaxation time measurements at different temperatures and different eoncentmtions provide information about the detailed structure and the relative arrangement of the nylon chains In solution．The results show that the temperature dependence of the relaxation behavior of nylon 11 solution is obviously different from that of ordinary polymer solutions With increasing temperature,the solvation is strengthened,i. e．the interaction between nylon 11 chain segments and solvent molecules is gradually strengthened．This leads to the dissociation of the hydrogen bonding among the nylon 11 chain segments,and the interaction among main chain of nylon 11 is then weakened．As a result the phenomenon of cohesional entanglement of the main chains due to hydrogen bending among them gradually disappeared．In these cases the solvent molecules come to bind the dissociated free CO and NH groups of nylon 11 molecules．The main chains are coiled and aggregated with a shape of random clew with a part of the solvent molecules included,making the motions restricted along with the α methylene protons of the CO groups staying in the interior of this random clew structure．The dependence of the relaxation process of nylon 11 solution on concentrations shows biexponential behavior,which suggests the existence of two states of the polymer．The fast relaxation component rapidly increases with increasing concentration,it corresponds to the increase of the cohesional entanglement of the main chain due to hydrogen bonding among the nylon 11 chains．This behaviour is related to the increase of the eohesional entanglement points in a unit volume．With the increase of the concentration,the nylon 11 solution gradually becomes soft．solid-like.
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发布时间：2021-03-19 - 摘要：Abstract A novel cation exchanger fiber w“prepared by irradiating grafting of acrylic acid at the surface of FE fibers The novel cation exchanger fiber not only has the advantages as a commercial cation exchanger fiber,but also has good corrosion resistance．It was found that the pH titration curve of the grafted mE fibet showed a sudden jump from pH=6 to 10,which was different from the behavior of a typical commercial weakly acid exchanger．This hovel g fted PTFE fibet was used to remove Cu“at different pH conditions．11le best pH value for the Cu“adsorption ale at 3～5．The highest adsorption capacity for Cu“is 107．48 mg／g．when the pH value is 5．The Cu“ ions eai'l be desorbed completely by dilute HCl solutions
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发布时间：2021-03-19 - 摘要：Organic rectorite clay (OREC)/polypmpylene(PP) nanocomposites were prepared by melt processing． OREC was obtained from natural rectorite through ion exchange with a quatemary ammonium salt The morphological features of the composites were investigated by using the X-ray diffraction and TEM techniques．It was found that the spacing of 001 crystalline planes for OREC slighfly increased,when it was blended with PP．The introduction of OREC showed evident positive effect on the mechanical and thermal properties of the composites．The tensile strength．elongation at break and impact strength for composites of 2％ OREC are 62.3％．285.9％ and 14.0％ higher than those of pure PP．respectively The thermogravimetrie temperature of 10％ weight lose of the composite sample is 50K higher than that of pure PP．
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发布时间：2021-03-19 - 摘要：The cell nucleation and cell growth of microcellular foaming in supercritical CO2 pressure quench process was investigated by means of dual depressurization and cooling Cyclic Olefin Copolymer (COC) was saturated under supercritical CO2 circumstance,and then the system was depmssurized to an intermediate pressure．After that,four methods of re-depressurization and cooling were adopted．Several novel cell structures were prepared in this way,such as cells with transitional layers and bimodal-size-distribution cens．It was found that most of the nuclei disappear or coalesce during cell growth process with only a small fraction growing to stable cells, and the final cell structure strongly depends on the cell growth process．Dual nucleation occurs only in a certain depressurization range．Final cell structures obtained in dual depressurization are closely correlative to the solubility variation of CO2 under corresponding pressures．
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发布时间：2021-03-19 - 摘要：In a previous paper,the rate of propylene oxide (PO) polymerization catalyzed by double metal cyanide complexes (DMC) had been determined to be proportional to the catalyst amount e and the square of monomer concentration M. The same reaction in the presence of substances contMning active hydrogens which were applied to regulate the molecular weights of the produced polyethers was inrestigated in this paper．All the reactions were carried out in 0.1 L autoclaves equipped with manometers and the induction period to and polymerization rate Rp were determined by means of pressure measurements．It was found that regulators with higher OH functionality showed greater influence on to,which was prolonged with addition of regulators except cyclohexanol．It was also found that the polymerization rate depended on the type of regulators and was inversely proportional to a linear function of the regulator concentration Tr．Moreover,a limited amount of water behaved as a strong bifunctional regulator which intensively influenced to and Rp；the presence of excess water deactivated the catalyst and hindered the polymerization．It Was revealed that the DMC catalyst and the monomer beth were necessary for the initiation of the polymerization．Based on this understanding,a possible mechanism was propesed for the polymerization and a kinetic equation as following was deduced,which was in well accordance with experimental results． Rp=KM2c/(1+kTr)
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发布时间：2021-03-19 - 摘要：Silk has high performance and super properties such as good luster,hangle and moderate moisture absorption,meanwhile it is prone to crease and yellowing and has low color fastness．So scientific researchers have been exploring new silk materials since 1980s．At present,the methods to modify silk focus on chemical ways of grafting,crosslinking and sericin fixation．In this work physical treatment of silk was investigated for improving its dyeing behavior and wear performance by using steam explosion at different pressure in a self-made maehine．The molecular configuration and morphology of the treated silk specimens were studied by means of electron micmscopy, infrared spectroscopy,x-ray diffraction and thermal analysis．It was found that the β-configuration of moleeules remained unchanged after steam explosion of the silk specimens,while the surface morphology and degree of crystallization of silks changed a lot．The binding force of micmfibrils became weaker．the specific surface area was enlarged and crystallinity decreased Experimental results also indicated that the solubilitv of silk in aqueous solutions of calcium chloride and ethanol was enhanced,and the reactive ability of the silks was improved．It was concluded that the steam explosion technique,as a physical method without pollution,can be used in pretreatment of silks.
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发布时间：2021-03-19 - 摘要：Surface contact disinfecting technique is a newly developed method for water sterilization．An experimental protocol to elucidate the anti-bacterial process and mechanism was proposed and applied to a novel surface contact disinfectant made of cellulose fiber grafted with DMAE-BC,using E.Coli,as a model bacterium．The minimum inhibition concentration (MIC) of the monomer,defined as a concentration at whichthe growth of E.coli.in water is completely inhibited,was determined by the plate counting method．MIC was then used as an index to characterize disinfection capability of the monomers．The disinfection mechanism of the monomer was further investigated by measuring the activity of β-galactosidase and observing the cell morphology with a scanning electron microscope (SEM)．To elucidate the disinfection process and mechanism of the grafted fiber,the steady state and dynamic adsorption of E．Coli．on the fiber as examined,respectively．The TIC-dehydrogenase activity and respiration activity of E.Coli. adsorbed on the fiber surface were also determined．The results showed that the sterilization process bythe graftedfiber was composed of two steps,in whichthe adsorption of E．Coli．bacteria on the fiber surface driven by electrostatic interaction was a fast process and cell-lysis was a relatively slow process．
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发布时间：2021-03-19 - 摘要：Higher cationic transference number is preferred for electrolytes of lithium ion batteries,and employing maeromolecular lithium salt is effective to improve the cationic transference number of the electrolytes．Therefore,a novel macromolecular lithium salt was synthesized through sulfation and neutralization of hyperbranehed pofyglyeidul．which was obtained by cationic ring-opening polymerization．13C-NMR analysis indicates the degree of branching of polyglycidol is about 0.5．and element analysis confirms the degree of substitution of hydroxyls can excess 0.6 after sulfation．FTIR and thermal analysis were used to characterize the hyperbranched polyglycidol and the macromolecular lithium salt derived from it For the application of this nmeromolecular lithium salt in lithium ion batteries．viscosity and conductivity of its solution in the mixed solvent of EC/PC/DMF were studied．The results show that the viscosity of its dilute solution is so low that it can be compared with that of small molecular lithium salts However．when the concentration of the solution is increased above 10％．the viscosity of the solution increases quickly and reaches a very high level at the concentration of about 30％．There exists a maximal conductivity of the solution while the concentration of the solution increases．and the maximum is reached at a concentration of about 10％．This can be explained by the concentration and mobility of free lithium ions in the solution．Besides．the maximal conductivity of the solution is about 1.7 mS/cm at 25℃．which can be compared with that of small molecular lithium salts．Considering the low viscosity and the high conductivity of its dilute solution,this macromolecular lithium salt has great potential application in inlithium ion batteries．
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发布时间：2021-03-19 - 摘要：Oil-soluble initiators are usually used in suspension polymefizationreaction,the polymerization reaction is taken place in the monomer droplets．In many cases,the kinetics of suspension polymerization is the same as that of bulk polymerization It is suitable for monomers which can not dissolve in water．but there are some deviations in the kinetics of polymerization when the monomer has partiall water solubility,such as methyl methacrylate (MMA),vinyl acetate (VAc) and aerylonitrile (AN)．The aqueous suspension homopolymerization of MMA at large water-to-monomer ratios is now investigated．Comparing with the bulk polymerization of MMA,there are large differences between the kinetic curves of suspension and bulk polymerization,and the water-to-monomer ratio will affect the kinetic curves of MMA suspension polymerization．In order to study the affecting reasons of monomer’s water solubility on the kinetics of its suspension polymerization in detail,a modified kinetic model for MMA suspension polymerization is presented on the basis of its bulk polymerization kinetic model and three assumptions．The three assumptions are：the amount of monomers dissolved in the aqueous phase should be deducted,the propagation and termination rate constants should be decreased,and a small amount of oil-soluble initiators may stay in the aqueous phase．Using the modified kinetic model,the effects of water-to-monomer ratio．polymerization temperature and initiator concentration are predicted．The simulated kinetic curves are in agreement with the experimental data．
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发布时间：2021-03-19
Research Article
- 摘要：Linear low density polyethylene from ethylene as an only monomer was prepared by the combination catalyst system of Et (Ind)2ZrCl2 and {2-[2-Me-4-Br-C6H3N=C(Me)]2C5H3N}FeCl2 activated with methylaluminoxane (MAO) The two catalysts were well matched in a single reactor and it was observed that the “comonomer effect”appeared in the in-situ eopolymefization of ethylene The comonomer effect was some strongly influenced by the molar ratio of Al to (Fe+Zr) and the polymerization temperatures At 60℃ and n(Al)/n(Fe+Zr)=2000,the maximum activity of the catalytic system(8.5×106g/mol·h) was 4.25 times higher than that of homopelymerizationof ethylene(2.0×106g/mol·h),andthe value of n(Fe)/n(Zr) was 0.5．At n(Al)/n(Fe+Zr)=1000,the maximum activity diminished．When polymerization temperatures increased,the maximum activity of the in-situ copolymerization decreased and the corresponding ratio of Fe to Zr also decayed．The eopolymers made from this catalytic system had the characteristics of low melting point (from 132.34℃ to 70.97℃),low density (from 0.9467g/cm3 to 0.9283 g/cm3) and narrow molecular weight distribution(from 2.29 to 1.86)．However,it’s no obvious influence of the comonomer effect on the physical properties of the copolymers．
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发布时间：2021-03-19 - 摘要：Nanocomposites based on ethylene-vinyl acetate (EVA) and montmorillonite (MMT) were prepared using melt mixing of the two components and an intercalation agent hexadecyl trlmethyl amrnonium bromide(CTAB)．The structure and pmporties of EVA/clay nanocomposites were characterized by XRD．TGA．Molau and mechanical properties tests．The results showed that EVA could be intereatated into the galleries of layered silicates in these samples．and the distance between layers of MMT in the EVA matrix Was 4.09 nm．Interface adhesion between the components in the EVA/MMT(95/5) nanocomposites was improved because the contact area between MMT layers and EVA matrix increased and there was a great deal of active sites on the surface of MMT layers．which could bind tighfly with the EVA matrix．Compared with those of EVA/MMT(95/5) composites without CTAB,the tensile strength,the Young’modulus and the tear strength of EVA/MMT(95/5) nanocomposites prepared in this work increased by about 20.2％．43.3％ and 17.1％．respectively．The thermal behavior of the composites was examined on a thermobalance in nitrogen．For the EVA/MMT(95/5) nanocomposites,the acceleration of EVA deacylation and the deceleration of thermal degradation were observed.
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发布时间：2021-03-19 - 摘要：Two cyclic olefin copolymers with the same comonomers and difierent monomer molar ratios were blended,and then the blends were saturated in supercritical CO2 at 20 MPa and various temperatures to prepare microcellular cyclic olefin copolymer blends by means of pressure quench．The cell density and cell diameter of microcellular polymers were calculated to investigate the effects of temperature and blending ratio on cell structures．The higher temperature results in larger cell sizes and smaller cell densities．The cell density increases remarkably and cell diameter decreases with increase in the content of the ingredient with hisher Tg．It is found that the stiffness of the matrix is the only possible material property that accounts for the differences in cell structure of micorocellular cyclic olefin eopolymer blends with difierent blending ratio．
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发布时间：2021-03-19 - 摘要：A novel non-metallocene supported catalyst,CpTi(dbm)Cl2/MgCl2 was synthesized in situ via reaction between CpTi(dbm)Cl2 and BuMgCl in heptane．The surface area,pore volume and crystal stmcture of the supported catalyst and MgCl2(in situ) which was obtmned by reaction of Mg and BuCl were characterized by BET and XRD methods,respectively．The surface area and pore volume of MgOl2(in situ) are higher than those of normal MsCl2,and the surface area and pore volume of the supporled catalyst are also high,The crystal structure of the supported catalyst is amorphous,which is similar to that of MgCl2(in situ)．Ethylene polymerization with MAO or AIR3 was investigated,which indicates that the activity does not decrease while AIR3 was used aS co-catalyst instead of MAO,so MAO can be absent in both the catalyst preparation and ethylene polymerization processes．The catalytic activity eaR be as high as 3.06×106gPE/molTi·h with tfiisobutyl aluminium(Ti-BA) as co-catalyst when polymerization temperature is 80℃．and Al/Ti molar ratio is 200．
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发布时间：2021-03-19 - 摘要：2-Phenyhhiophene(P2PT) has been electrochemically polymerized in pure boron trifluofide diethyl ether (BFEE) solutions or in a composite electrolyte of BFEE and trifluoroacetic acid (TFA)．The addition of a certain amounl of TFA into BFEE lowered the oxidation potential of the monomer,accelerated the polymerization and also increased the current efficiency of the electrosyntbesis．The morphology and electrochemical behavior of as-grown P2PT films were studied by scanning electron microscopy and cyclic vohammetry．Poly (2-phenyhhiophene) in dedopod state is soluble in usual organic solvents such as tetrahydmfuran and chloroform,etc．Its structure has been examined by infrared,Raman and UV-visible spectroscopies．The molecular weight of the polymer was measured to be about 800 Da．Fluorescent spectral studies indicate the polymer is a blue-green light emitter．
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发布时间：2021-03-19 - 摘要：Phase transitions of polymer liquid crystals may be induced not only by changes of temperature or polymer concentration．but also by external electric,magnetic or other orientational fields．In this paper the phase behavior of polypeptide liquid crystal solutions,such as PBLG/TCE and PBLG/CHCl3/TFA solutions, was studied in the presence of an external electric field．It was found that the liquid crystal phase was stabilized when the extemal electrical field was applied and the area of liquid crystal phase was broadened．Qualitatively,the experimental results are in good agreement with the theoretical results calculated by a lattice model previously．The information obtained may be used to develop new routes for processing rigid-flexible block copolymers with better mechanical pmpeflies and to construct molecular devices for processing and storing infommtion．
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发布时间：2021-03-19 - 摘要：Nanocomposites wele prepared by a simple technique of emulsion polymerization using VC monomer and Na+ -montmofillonite．The nano-structure of the composites was studied with the aid of X-ray diffraction and transmission electron microscopy．and the mechanical and thermal properties of the composites were also tested．The results showed that the silicate layers were delaminated or partially exfoliated in the PVC matrix．The impact strength of the material with 2.1％ MMT was almost two times as high as that of pure PVC．while the tensile strength decreased little．However,the mechanical strength of the composites began to decrease with further increasing the amount of MMT．The TGA results showed that the temperature,at which a 50％ weight loss of the composites occurred．was highel-than that of pure PVC The vicat softening temperatures of composites were enhanced with increasing MMT content．
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发布时间：2021-03-19
Research Bulletin
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