最新刊期
卷 ， 期 6 ， 2000
- 摘要：A series of hydrogels in the form of rod were prepared from Kappa-carrageenan(KC), N-vinyl pyrrolidone) (N-VP) and polyethylene glycol dimethacrylate(14G) by gamma radiation with 60Co γ source at room temperature.The properties of the prepared hydrogels,such as the gel strength,the gel fraction and the swelling behavior were investigated. N-VP blending with KC could get excellent KC/PVP hydrogels at certain radiation conditions.The addition of 14G into KC/ N-VP system reduced the gelation dose.The gel strength of KC/PVP blend hydrogels containing 14G was higher than that of hydrogels without 14G,but their equilibrium degree of swelling (EDS) was edcreased becuse of higher crosslinking.With the increasing of KC content in the prepared hydrogels,both the gel strength and the EDS were improved together.In addition,the dose and dose rate influenced greatly the preparation and properties of the hydrogels.The gel strength of KC/PVP hydrogels decreased with the increasing of dose-reat,but increased with the increasing of dose from 0 to 30kGy,and then decreased after 30kGy.The change of swelling behavior of KC/PVP hydrogels with the dose/dose-rate is just contrary to the change of the gel strength.The experimental analyses also showed that the polymerizing and crosslinking reaction of N-VP was quicker than the degradation of KC at low dose (less than 30kGy),and the degradation of KC was inhibited in N-VP/KC mixture systems.So an interpenetrating polymer network hydrogel composed of PVP (a chemical crosslinking network) and KC (a physical crosslinking network) was proposed here.
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发布时间：2021-03-19 - 摘要：The interface behavior between essence and ethylene-vinyl acetate copolymer pallets was studied so that necessary data were obtained to guide the preparation of fragrant masterbatch．The adsorption typeand wettability between essence and the copolymer pallets were analysed by measurements of fouriertransform infrared spectrum,surface tension,contact angle and specific surface area．The technical factorsaffecting absorptivity such as the charge ratio,temperature,pressure and stirring speed were studied by series of adsorption experiments The results showed that the adsorption of essence on the surface of ethylene-vinyl acetate copolymer pallets is physical in nature Essence couldn’t moisten the surface of ethylene-vinyl acetate copolymer pallets absolutely,but it could be soaked into the surface of the pallets partly．Adsorptivity could be increased by enhancing the temperature,pressure and stirring speed,but the extension of adsorption time had little influence on adsorptivity．
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发布时间：2021-03-19 -
CONFIGURATION-DEPENDENT PROPERTIES OF POLY(OXYETHYLENE) IN THE THIRD-ORDER INTERACTION APPROXIMATION
摘要：On the basis of rotational isomeric state (RIS) theory,the first-order,second-order,and third-order conformational energies were calculated for poly(oxyethylene)\[(CH2—CH2—O)x] (POE)chain using semiempirical potential function.Configuration-dependent properties of POE chains,such as the characteristic ratio r2>/nl2 ,the dipole moment ratio μ2>/nm2 and their temperature coefficients dln r2>/dT and dln μ2>/dT ,were calculated using the statistical weight matrix method,where r2> in the meam-square end-to-end distance,μ2> is the meansquare dipole moment,n means the length of chain,l and m are the bond length and bond dipole moment,respectively.Results showed that,for long POE chainsr2>/nl2=4.9,dlnr2>/dT=-1.5×10-3K-1,μ2>/nm2/nm2=0.49,and dlnμ2>dT=2.8×10-3K-1.All these values are better than tose obtained from the second-order interaction approximation,and the characteristic ratio and the dipole moment ratio are in good agreement with early experimental findings.- 2
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发布时间：2021-03-19 - 摘要：A novel bischloride monomer containing cyclohexene moieties [1-methyl-4,5-bis(chlorobenzoyl)cyclohexene] was successfully prepared.The compound is white plane crystally,b.p.126～127℃,it was studied by FT IR, 1H NMR and MSD.Consequently a novel poly(aryl ether ketone)containing the of cyclohexene and phthalazinone moieties polymer was prepared by the nucelophilic displacement reaction of 1-methyl-4,5-bis(4-chlorobenzoyl)cyclohexene and-4-(3,5-dimethyl-4-hydroxyphenyl)-2,3-phthalazin-1-one.The polymer was studied by FT-IR,1H-NMR,DSC,X-ray diffraction.It has been proved that it was a amorphous polastics with high glass temperature (Tg=216.1℃).It was soluble in some solvents at room temperature.It was also intermediate product of cross-linked copolymer and grafted copolymer.
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发布时间：2021-03-19 - 摘要：New kinds of solid-solid phase change materials(PCMs) with netted structure have been prepared.In these materials,a flexible polymer PEG (polyethylene glycol) has been taken as functional branches,with which the energy storage and energy release can be proceeded by phase transition between its crystal state and amorphous state.And a rigid polymer CDA (cellulose diacetate) has been taken as skeleton,which ensures the solid-nature of PCMs during the phase transition.IR,X-ray,TG,DSC,TEM,polarizing microscopy and so on were used to study the structure and properties of PCMs.The former studies showed that these new PCMs have typical colid-solid phase transformation property,quite good energy storage effect and have better thermal stability.In this paper,the effects of molecular weight and weight percentage of PEG in composition on energy storage properties were discussed in detail.The results showed that PEG in composition on energy storage properties were discussed in detail.The results showed that PCMs with different latent heat,different phase transition temperature and different mechanical strength can be obtained by means of modifying the molecular weight and weight percentage of PEG.
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发布时间：2021-03-19 - 摘要：The coordination of a fully deacetylated chitosan with zinc ion was studied in the homogeneous reaction condition．The composition and structure of chitosan-Zn (Ⅱ) complex were investigated by elemental analysis．infrared and UV-visible spectrometry solid state 13C—NMR,thermogrativimetric analysis and X-ray diffraction The results of elemental analysis show that the ratio of glucosamine repeat unit to Zn(Ⅱ) was 2：1 with the complex formation in a pH=7 solution．The absorption at 3420cm-1 due to O—H and N—H stretching shifted to 3391cm-1; the absorptions at 1597cm-1 due to N—H stretching and at 1093cm-1 due to secondary alcohol—OH stretching shifted to 1620cm-1 and 1062cm-1, respectively．But the absorption at 1038cm-1 due to primary alcohol—OH did not shift supporting that both the amino and secondary hyrdroxyl groups of chitosan molecules are coordinated to Zn (Ⅱ)．Comparing the 13C-NMR spectra of chitosan and chitosan-Zn(Ⅱ) complex,the shifts of the key bands showed that Zn (Ⅱ) is coordinated to the—NH,and secondary alcohol—OH of chitosan molecules．Marked difference of the characteristic peaks of both chitosan and chitosan—Zn(Ⅱ) complex was not observed in the x-ray diffraction pattern．indicating that the extended 2-fold helical conformation of the chitosan molecule is retained even after the complexation．Final decomposed product of the complex is sulfate zinc,and the residue percentage is 28．8％and is correspond to the calculated value of 29．0％,accordign to the composition of elemental analvsis of chitosan-Zn(Ⅱ) complex．The structure of the complex seems to correspond to Zn(chitosan)2SO4·4H2O at pH=7．Thecomplexisinsolubleinwater,acetone and ethanol,partly solublein dilute fclrmic acid solution,DMF and DMSO,completely soluble in dilute hydrochloric acid solution.
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发布时间：2021-03-19 - 摘要：The PP alloy was synthesized directly in the reactor with a 4th generation Ziegler-Natta catalyst.It is very different from mechanically blended PP alloys,its properties,especially its impact strength,are superior to those of the latter.However,so far the studies on the stucture of this kind of PP alloys have not been reported.The microstructure of a PP alloy was characterized by IR,DSC,and 13C-NMR.The sample was first fractionated and 8 fractions were obtained.The IR analysis showed that the ethylene content of each fraction is different.Except for the first fraction,which is an elastomer,the others are all hard powders at room temperature.Therefore,the fractions above 50℃ perhaps are all composed of ethylene-propylene block copolymers.DSC analysis showed that the melting curve of the PP alloy became broadened compared with that of i-PP,and a small peak appeared at 120℃.The extracts of PP alloy in boiling heptane and every fractions of PP alloy are composed of ethylene-propylene blocks,whose sequence length are very different.The 13C-NMR spectrum of fraction at 90℃,similar to other fractions at 50～100℃,also indicated that there are long ethylene sequences in macromolecualr chains of PP alloy.According to the above analysis,a conclusion was reached that the E-P copolymer in PP alloy is composed of EPR and E-P blocks,with different ethylene sequence length.This polydispersity structure in PP alloy made it possess very high impact property.
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发布时间：2021-03-19 - 摘要：Based on the thermally reversible Diels-Alder reaction between the cyclopentadiene and dicyclopentadiene,the dicyclopentadienyl dicarboxiate derivatives were synthesized by usual organic reaction,and it was taken into PVC molecular chain as a covalent crosslinking agent.The effects of crosslinking agent,catalyst and activator on the crosslinking rate,mechanical properties and the flow feacture of crosslinekd PVC were also investigated in detail.It has been found that when PVC was reacted with crosslinking agent in the melt directly,the crosslinking rate was low(crosslinking reaction taking place at 190℃ for 36min,the gel content of the system was only 26.3%),when the ammonium salt as catalyst and polyglycol as activator were added into the reactio system at a optimum ratio,the crosslinking rate can raise 7～9 times.The crosslinked PVC not only has good thermally conversion behavior through the analysis of reaction solubility,DSC and flow curves,but also exhibits flow behavior similar to uncrosslinked PVC.Based on the recipe of soft PVC,thermally teversible covalent crosslinked PVC with better mechanical properties in comparison with the original one was prepased.
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发布时间：2021-03-19 - 摘要：The micellization of amphiphilic graft copolymer PMMA-g-PEO in selective solvents has been examined by means of NMR,TEM,DLS and viscometry.It has been found that the amphiphilic graft copolymer has a strong surfactant activity;in chloroform,the copolymer is dissolved in a stretched polymer conformation;however, the graft copolymer forms a reversed-micelle in selective solvent toluene and a micelle in water.Micelle formation of PMMA-g-PEO in selective solvents is strongly dependent on concentration,temperature,polymer structure etc..Moreover,is has been found that the reversed-micelles are of a spherical structure in shape,the diameter of the reversed-micelles is increased with increasing the concentration of amphiphilic graft copolymer PMMA-g-PEO in selective solvent toluene,the hydrophilic graft chains PEO can form a dense coil through hydrophilic interactions,with the hydrophobic backbone facing outwards forming a hydrophobic shell.
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发布时间：2021-03-19 - 摘要：The crystallization kinetics of polyethylene blends (metallocene based HDPE and commercial LDPE) were investigated for studying liquid-liquid phase separation in these blends．All the quenched blend samples were first melt at 180℃ for 5min．Isothermal crystallization was taken at appropriate temperature(atemperature low enough for the HDPE to crystallize but high enough that the LDPE would remain molten)using differential scanning calorimetry(DSC).In contrast,when the melt was held for 5min or 15min at 150℃ (in the region of liquid-liquid phase segregation),the kinetics of the isothermal crystallization of the annealed samples had a distinctly faster tendency than the samples without annealing and there were no difference when extending the annealing time Based on Hoffman theory and further experimental data,the possibility of nucleation and co-crystallization at being kept at 150℃ for 5min or 15rain was eliminated So it is strongly indicative of the existence of liquid-liquid phase segregation in the melt of polyethlene blends.If the annealed samples did not undergo phase separation between two components,their crystallization kinetics should be the same as those observed for the unannealed samples Now in the present case,phaseseparation occurs,then the crystallization kinetics becomes faster in order to approach that of the pure HDPE This conclusion is based on a widely accepted assumption It says that when both components are miscible and one of them is crystallizable,the crystallization rate of their blend is slower,compared to that of its pure components due to the rejection of the noncrystallizable component from the pristine fraction in the crystallization process Annealing blends of HDPE and LDPE at 150℃ induced phase separation in the the melt．HDPE enriched in these blends brought about an accelerated kinetics for the annealed samples
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发布时间：2021-03-19 - 摘要：A new kind of cis-dicarbonyl rhodium complex,which contained S and O atoms as uncoordinated donors,has been synthesized.After studying its intramolecular substitution reaction through IR and XPS data,the result indicated that the weak S→Rh and the weaker O→Rh coordination bonds can replace the strong Rh-Cπ back donation bond to form tetradentated complex with the elevation of temperature and without the protection of CO.So the rhodium complex will not decompose for the drop of the terminal carbonyls and its stability is enhanced.The intramoleculat substitution reaction is reversible.In the atmosphere of CO,the tetradentated complex will recover to bidentate complex with cis-dicarbonyl.
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发布时间：2021-03-19 - 摘要：As-spun PEN fibers prepared by melt spinning ranged from 0.5 to 10km/min were treated under different conditions like cold drawing.constrained annealing and hot drawing.Structure changes during the treatment were studied through WAXS and DSC testing.The result shows that during the cold drawing process below Tg,stretching induced crystallization can occur and thus α-form crystal formed in the cold drawn samples whose precursor was spun at low speed.However,when the same precursor was subjected to constrained annealing,its amorphous characterstics remain unchanged even the annealing temperature was 200℃ These results may indicate that the stretching stress is more important than elevated temperature in forming a crystals.The crystalline structure of the hot drawn samples depends significantly on the morphology of the precursor fibers.When the as-spun fiber was prepared at low speed and the fiber structure is predominantly amorphus,hot drawing process will induce a-form crystals.It is observed that the predominant β-form crystals in the as-spun fibers wound at higher speeds were partly transformed into a-form crystals during the hot drawing.And the level of this transition depends on the perfection of the β-form crystal in the precursors.The higher the spinning speed,the more perfect the β-form crystals in the as-spun fibers,and the lower the level of this transition,and accordingly,the more the remainder of the β-form crystals in the hot drawn samples.
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发布时间：2021-03-19 - 摘要：Isothermal and non-isothermal crystallization kinetics of three metallocene-catalysed short-chain-branched polyethylene (SCBPE) fractions with different degree of branching were investigated by using differential scanning calorimetry (DSC).Narrow molecular weight fractions (Mw=20,000 and Mw/Mn3 per 1000C) are 1.6, 10.4, 40 respectively.The regime Ⅰ-Ⅱ transition temperature are 119.8℃, 115.9℃, 113.3℃ with the decreasing of degree of branching.Increasing the branch content decreases the rate of secondary nucleation,i,relative to the rate of surface spreading and so increases the range of supercooling over which regime I exists.The rate of bulk crystallization for both isothermal and non-isothermal crystallization decreases with the increasing of degree of branching.Both Ozawa Equation and Kissinger Equation are invalid for non-isothermal crystallization kinetics of SCBPE fractions,tha means the effects of the branched chain on crystallization process are more complex than expected.
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发布时间：2021-03-19 - 摘要：Based upon the DSC,DMA,TEM and SEM observation,a study was made on the structure and property of ethylene-propylene diene monomer(EPDM)／ternary-nylon-copolymer(nylon6／66／1010=20／10／70)(PA) blending systems with excellent properties．The results show that there are three kinds of structure such as lollows：After EPDM,PA and chlorinated polyethylene (CPE) being melt blended in 160℃,disperse particles,composed of PA and CPE would be formed．Because of chemical reaction,CPE anchored or inserted into PA The junior structure refers to dispersed particle itself It reduces the polarity of PA and improves the compatibility of PA and EPDM．On the other hand,it makes modulus and crystallinity of PA closer to those of EPDM．Some special treatment changes the shape of dispersed particles into a micro-fiber(intemadiate structure) that could reinforce the EPDM matrix with smaller amount of PA Also,it could improve magnificently the tear strength,especially hot tear strength of EPDM．EPDM／PA blend,named as micro-fiber rubber compound,has much better elongation at break than short-fiber rubber com Dound and the reason has been given Only under the effect of external force,the senior structure,which is composed of aggregation bodies,comes into being．Each aggregation body,which could be proved by analysis of SEM observation of surfaces of fractured specimen,includes certain amount of micro-fibers It is these sophisticated structures that make the blending system embrace merits of both EPDM and PA and gain excellent comprehensive properties．Compared with main properties of rubber compound cited in hterature．EPDM elastormer reinforead by nylon has satisfactory mechanical properties and excellent heat and oxygen．resistance properties．
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发布时间：2021-03-19 - 摘要：The effects of molecular weight,degree of substitution and side chain length on the liquid crystalline behaviors of chitin derivatives have been studied.It is known that the molecular weight affects the liquid crystalline behaviors evidently.To study the effect of degree of deacetylation (D.D.),the samples with different D.D. but with same molecular weight must be prepared.These samples were prepared by acetylating chitosan with different amount of acetic anhydride and different reaction time.The method took the advantage of less degradation of molecular chains and no acetylation on —OH of C3 and C6.The chitosans with different D.D.all exhibited typical liquid crystalline texture.The chitosan sample with about 50% D.D. was found to be water soluble and have the maximum critical concentration of lyotropic liquid crystal in both dichloroacetic acid and water.The critical concentration values in water were much lower than those with the same degree of deacetylation in dichloroacetic acid.The poorer liquid crystallinity of chitosan with about 50% D.D.can be explained by the random distribution of acetylamino-D-glucose units and amino-D-glucose units.
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发布时间：2021-03-19 - 摘要：In VDC-AN suspension copolymerization,the effect of water solubility of AN on composition of both the monomers and the copolymer was studied.The results showed that the composition of the copolymers was significantly different from the bulk model prediction,because AN was partially water soluble and it decreased the AN content in organic phase.In this work for exact calculation of the composition of VDC-AN copolymer,it was supposed that transfers of the dissolved AN to the organic phase were much faster than polymerization,and AN phase partition in VDC/water system was nearly balanceable.The Marker formula describing AN phase partition between VDC and water was used in the correction of AN content in organic phase,and then the composition of VDC-AN copolymers was calculated with the Mayo-Lewis formula using the reactivity ratio values from the bulk polymerization literature.It was found that the calculated data agree with the experimental results.
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发布时间：2021-03-19 - 摘要：Aliphatic poly(cyclohexene carbonate),which has a Tg of 120℃,was sythesized by coordinate-catalytical copolymerization of carbon dioxide and cyclo-hexene oxide(CHO) with polymer-supported bimetallic catalyst (PBM) and was characterized by IR,NMR and DSC measurements.The thermal degradation of copolymers was studied by TG measurement,and found that 5% and 50% weight loss temperature (t5%, t50%) were 177℃,273℃,respectively.The copolymerization of CO2,cyclohexene oxide (CHO) and propylene oxide (PO) was also studied to evaluate the influence of mole percentage of cyclohexene oxide (CHO) on Tg."End capping"can raise t5% to 210℃.The copolymerization of CO2,cyclohexene oxide (CHO) and phenyl isocyanate (PI) can increase the intrinsic viscosity ([η])but decrease the Tg.
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发布时间：2021-03-19 - 摘要：A novel grafting copolymer was synthesized by reacting DL-lactide with corn starch in N,N-dimethylacetamide(Me2NAC) in the presence of triethylamine(NEt3) and anhydrous lithium chloride．The effect of reaction time and the molar ratio of DL-lactide to structural unit of starch on monomer conversion (C％),grafting(G％)and grafting efficiency(GE％)has been studied The C％,G％and GE％couldapproach 37.3％．179.7％and 68.0％。respectively when the molar ratio of DL-lactide to structural unit of starch is 10：1．the grafting copolymerization was carried out at 80～85℃ for 4h in a nitrogen atmosphere．Several techniques such as Fourier transform infrared(FTIR) spectroscopy,differential scanning calorimetry(DSC) and X-ray diffraction (XRD) were used to characterize the grafting copolymer．FTIR spectrumshows an absorption band at 1740cm-1 confirming the formation of ester bond,indicating the starch／DL-lactide grafting copolymer was produced．The DSC characteristic result showed the melting temperature of the grafting copolymer elevated slightly as the molar ratio of DL-lactide to glucose structural units of starchincreased and the X-ray diffraction pattern showed the synthesized grafting copolymer was an amorphouscopolymer．The degradability of grafting copolymer was tested with the aid of acid,alkali and microbe The weight loss of the grafting copolymer was 100％ after 70h in0.5mol／L hydrochloric acid solution at 30℃． but the weight loss of the grafting copolymer approaching to 100％after 35h in 0．2mol／L sodium hydroxide solution at 30℃．the weight loss of the glucose structural unit of starch and DL-polylactide chain in the grafting copolymer was 41.8％ and 24.0％ after 20 days and 30 days of incubation with bacillus subtilis and staphylococcus aureus at 37℃ respectively The grafting copolymer produced can be used as a component in hot-melt adhesives and as an impermeable coating for paper and cardboard．
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发布时间：2021-03-19 - 摘要：Polyhydroxyalkanoate(PHA) is a family of carbon and energy storage materials synthesized by many bacteria,its hydroxyalkanoate monomers have diversified structures.A broad screening process using the FT-IR technique developed by us previously was carried out.Samples were collected from various geological locations around the country.It was found that PHA compositions depend very much on the geological locations.In some locations,bacteria mainly synthesized short-chain-length PHA(scl PHA) consisting of monomers with four to five carbon atoms,in other locations,medium-chain-length PHA(mcl PHA) consisting of monomers with six to sixteen carbon atoms were accumulated by inhabiting bacteria.Additionally,the synthesis of blend polymers consisting of PHB,scl PHA and mcl PHA is a common phenomenon among the bacteria studied.40% of the 371 strains cultivated on six substrates is able to synthesize PHA,with many of them making blends of PHB and mcl PHA.This result will help polymer researchers to identify sources of PHA synthesis.
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发布时间：2021-03-19 - 摘要：Sol-gel technology,because of the use of homogeneous liquid solutions and the ability to form gels at room temperature,provides an attractive route to the preparation of a three-dimensional inorganic network,especiallyfilms．Athree-dimensional network of organic／inorganic hybrid nonlinearoptical(NLO)materials can be prepared by doping optically active organics into sol-gel liquid solution or bonding organic chromophores with inorganics at the temperature below decomposition temperature(Td)of organic chromophores without risking the degradation of organic components．The properties of hybrid NLO materials Call be tailored by changing the starting chromophores The three-dimensional networks can restrict the dipole alignment relaxation of NLO chromphores,so the resulting NLO materials have high NLO susceptibility,low optical loss,high glass transition temperatures and good high-temperature stability．In this report,a new kind of bonded organic／inorganic hybrid NLO materials(DO3ASD)containing 4-Nitro-4’-amino azobenzene was synthesized through sol-gel process by using γ-glycidoxypropyl trimethoxysilane(KH560) as intermediates The preparation process and quality of DO3ASD were studied and characterized by FTIR,1H-NMR,UV-VIS,TGA,DSC,SEM and SHG measurements The results show that this bonded polymer film has a high NLO coefficient(d>33)of 5.79×10-7 esu,and exhibit good SHG stability,the d33 values cad maintain about 93.5％ of its initial value at room temperature for 90 days,and can maintain aboUt 60％ at 100℃ for 300min These facts demonstrated that the chemical bonding of the chromophores to the SiO2 networks can effectively reduce the dipole alignment relaxation of chromophores,thus lead to a better orientational stability．
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发布时间：2021-03-19 - 摘要：A group of Poly(N-iso-propylacrylamide-co-acrylamide) with different component ratio have been prepared in this work.The change of the fluorescence spectrum of probes dissolved in the copolymer solution in water was studied with increase of temperature.The results indicated that the lower critical solution temperature (LCST) depends on the component ratio of the copolymers. The higher contents of AM in copolymers,the higher LCST was observed.By comparison of the two methods of using fluorescent probes—labeled on copolymer backbones and dissolved in aqueous solutions,it was found that the labeled probe method exhibits higher sensitivity and is more suitable for the study of the phase transition of polymer solutions.
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发布时间：2021-03-19 - 摘要：The effects of mixing conditions including mixing temperatures and mixing time on the intercalation and exfoliation behaviors of epoxy/n-hexadecyllammonium-montmorillonite clay mixtures and their nanocomposites after curing with curing agent (MeTHPA) and catalyst (DMBA) have been investigated by XRD and TEM.The physical-mechanical properties of the nanocomposites have been measured by tensile testing machine,charpy impact test and heat distortion test instruments.The X-ray diffraction patterns revealed that organoclay was easily intercalated by the epoxy resin during mixing process.Either an intercalation or an exfoliation nanocomposite might be obtained after the mixtures were cured by the curing agent system.There is a mixing temperature-time-intercalation exfoliation transition diagram(3-T diagram).Only under certain mixing conditions,the exfoliation nanocomposite materials could be formed.The mechanical properties of exfoliation nanocomposite materials were better than those of the intercalation ones.
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发布时间：2021-03-19 - 摘要：A novel half-titanocene compound,(η5-pentamethylcyclopentadienyl) titanium triallyloxide (Cp*Ti(OCH2CH=CH2)3), and modified methylalumiloxane (mMAO) were synthesized and employed in the study on ethylene\|propylene copolymerization.The influences of the amount of residual TMA in MAO,ethylene-propylene feeding molar ratio,polymerization temperature and the concentrations of catalyst and mMAO on activity of ethylene-propylene copolymerization,molecular weight of copolymer have been discussed in detail.It was found that the catalytic activity increased with the decreasing of the amount of residual TMA in MAO,such as from 22.3% to 14.8% TMA content in MAO,resulting in the Ti(Ⅳ)species content from 40.8% up to 88.8%,which indicated that the Ti(Ⅳ) species is favorable for the ethylene-propylene copolymerization.The activity also increased with the decreasing of ethylene molar ratio in feeding comonomer,it perhaps related to the chain structure and physical state of copolymer.The catalytic activity was affected obviously by the polymeric temperature,but it was not as sensitive in higher ethylene-propylene feeding molar ratio(E/P=70:30) as that in lower E/P feeding ratio(E/P=10:90),this performance suggested that higher temperature was more suitable for ethylene polymerization than for propylene polymerization.The varying ranges of Al/Ti=140～230mol/mol and [Ti]=1.0×10-3～1.2×10-3mol/L weght random ethylene-propylene copolymer elastomers,most of those can be soluble ni hexane,were obtained by the catalyst.
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发布时间：2021-03-19 - 摘要：Stereo-structure and monomer sequence distribution of the ethylene-propylene copolymers obtained from half-titanocene catalytic system,(η5-pentamethylcyclopentadienyl) titanium triallyloxide (Cp*Ti(OCH2CH=CH2)3) combined with methylalumiloxane (MAO),have been investigated by 13C-NMR spectra.The monomer reactivity ratios of the copolymerization with this catalyst were calculated from the monomer sequence distribution in 13C-NMR spectra, r1=7.91±0.06 for ethylene,r2=0.135±0.03 for propylene,and the products r1r2 for all runs in various feeding monomer ratio are almost equal to one (r1r2≈1).The monomer reactivity ratios were also determined according to Fineman-Ross method,the values of r1=7.74,r2=0.134 and r1r2=1.04 are very close to those of calculating dbove by 13C-NMR analysis.These results indicated that the copolymers produced are random ones.The ethylene-propylene copolymers could be fractionated by successive solvent extraction and gave two fractions of ether-soluble and hexane-soluble.These two fractions showed slight differences in their monomer sequence distribution and monomer reactivity ratio.The ether-soluble fraction contained more propylene units,while more ethylene segments existed in the hexane-soluble fraction.
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发布时间：2021-03-19 - 摘要：The ethylene-propylene copolymers obtained from half-titanocene catalyst,( η5-pentamethy-lcyclopentadienyl) titanium triallyloxide (Cp*Ti(OCH2CH=CH2)3) combined with methylalumiloxane (MAO),have been characterized by several methods including solvent extraction,FT-IR,GPC,X-ray,DSC,TG and DMA mesurements.The ethylene-propylene copolymers could be fractionated by successive solvent extraction.Most of them gave mainly two fractions of ether-soluble and hexane-soluble characteristics,some others contained partly hexane-insoluble fraction.These two ether-soluble and hexane-soluble fractions have a similar chemical composition and structure in FT-IR spectra.They show no melting point in DSC mesurements and a wide dispersion peak of non-crystalline phase in X-ray diffraction analysis,indicating that the copolymers are random ones.Copolymers containing more ethylene segments have shown some sharp peaks indicating they are crystal line.The glass transition temperature(Tg) of copolymers increased with the increasing of propylene molar ratio in feeding comonomer from DMA mesurement.Ethylene/propylene copolymers have shown high molecular weight and narrow molecular weight distribution in GPC measurements.
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发布时间：2021-03-19
Research Article
- 摘要：Ferrocenediyldimethylsilane monomer has been synthesized.A series of poly(ferrocenyl dimethylsilanes) with different molecular weights have been prepared by thermal ring\|opening polymerization of 1,1′-Ferrocenediyldimethylsilane at different polymerization time. It was found that with increasing polymerization time from 5min to 60min the molecular weights of resultant poly(ferrocenyl dimethylsilanes) increase from Mn=1.7×104 to Mn=1.7×105. The reactions of ferrocene with tetracyanoethylene (TCNE) and the reactions of poly(ferrocenyl dimethylsilanes) with tetracyanoethylene (TCNE) were investigated by ESR. A signal with g≈2 was detected from resultant poly (ferrocenyl dimethylsilane)/TCNE system,which indicates the formation of poly (ferrocenyl dimethylsiliane)/TCNE charge transfer complex.
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发布时间：2021-03-19 - 摘要：Polyimide (Kapton) was implanted with He+ ions at energies of 1MeV,1 5MeV,2MeV,respectively, and its surface hardness and wear resistance were characterized.Results of tests indicated that hardness values of all implanted specimens increased over those of the unirradiated material, particularly for specimens implanted at 2MeV.The hardness improved from 0.55GPa for unimplanted Kapton to 6.7GPa,corresponding to a factor of improvement of about 12.Reciprocating sliding wear tests using a steel ball counterface yielded significant improvements for the 1MeV energy implantation. A similar wear improvement was not obtained for the other two energy implantation.It showed that optimum wear properties did not exist at the highest implantation energy but rather at an intermediate energy.These improvements in properties are apparently related to the effectiveness of cross-linking.The results of X-ray photoemission spectroscopy (XPS) proved that after irradiation,the contents of O,N atoms decreased in the surface and a new three-dimensional covalent bonded structure,mainly constructed by phenyl,was formed.
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发布时间：2021-03-19 - 摘要：The expression of the rule of mixtures for the tensile strength of binary polymer blends was modified.The two factors which reflect the interfacial behavior between the two phases and the structural affection respectively, F and M ,were maintained in the modified expression.The modified expression was applied to the systems of NR/EPDM,LDPE/PS,PVC/PMMA and PVC/PS blends. F and M according to the model were calculated by the method mentioned in the paper. The obtained F values were in accordance with the solubility parameters of these polymers.The calculated values according to the modiied expression also indicate that co-curing increases structural affection and compatibilizer mainly progresses interfacial situation.The results showed that modified expression and structural affection of polymer binary blends.
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发布时间：2021-03-19 - 摘要：A series of ethylene-vinyl alcohol copolymers (EVOH) with different comonomer contents were studied by both solution state and solid-state high-resolution 13C-NMR spectroscopy. A new assignment of 13C-CP/MAS spectrum of EVOH was given. It was demonstrated that the triple splitting of the signal of methine carbon of the vinyl alcohol unit in 13C-CP/MAS spectrum is caused by sequence distribution,tacticity and intra and inter molecular hydrogen-bonding interactions.
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发布时间：2021-03-19 - 摘要：The plateaumodulus of polyphenylquinoxaline (PPQ-E) films has been obtained byfromtheir dynmic mechanical properties curves．Using these data,the entanglement density of PPQ-E films,2.37×1026m-30．39mmol／cm3,has been estimated．The deformation mechanism of polyphenylquinoxaline (crazing mechanism．or shear yielding mechanksm,or both),can be predicted according to entang-lement density values. The changes in morphdogy of PPQ-E films during tensile ddormation have been observed by Pohrized Light Microscope．The resultshows that crazing first appears in the tensile process,then shear yidding appears．It neois to point out the craze is terminated by micro-shear band andthe diection of araze in shear band is also changed,which prevents the crazegrowth into crack and avoid the failure of material This result is inaceordance with the theprediction on the basis of the entangleneat density data The morphology and structure of crazes in PPQ-E thin film have been determined by TEM．The craze morphology of PPQ-E is mainly fibril craze consisting of micro-fibrils and micro-voids,the interface between bulk and craze is distinct．Multiply crazes,blunting of craze tip and shear deformation zone are also observed. This result reflects the accordance of entanglement density and the morphology and structure of crazes.
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发布时间：2021-03-19 - 摘要：Photodynamic polymers,possessing interesting properties such as surface relief gratings among others,have attracted considerable attention in recent years and are promising for information industries such as data storage.However,the relationship between the degree of functionalization and properties of photodynamic polymers has not been thoroughly investigated yet.Two kinds of azo photodynamic polymers with different degree of functionalization were synthesized by post azo coupling reactions. Tgs of photodynamic polymers increase as the degree of functionalization increasing.The polymers synthesized exhibit significant photodynamic behavior.
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发布时间：2021-03-19
Research Bulletin
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