最新刊期
卷 ， 期 3 ， 1997
- 摘要：Water free electrorheological (ER) fluid was prepared using silica supported γ (aminopropyl) triethoxysilane [NH2(CH2)3Si(OEt)3] as the dispersed particle.The effects of factors such as electric field strength ( E ),shear rate (γ· ), particle content,type of dispersion medium and small polar molecule on the rheological properties of this ER fluid were investigated.It was found that the fluid using silicone oil as the dispersion medium and contains 15%(g/ml) particle,without any activator,and at the shear rate of 8.066s-1,when E increases from 0to 1.666 kv/mm,the apparent viscosity(ηn)of the fluid increased from 0.396 Pa.sto 16.669Pa.s.The higher the γthe smaller the ηa.The ηa increases with increasing of the particle content.The ER effect of the fluid using silicone oil as the dispersion medium is better than taht of using mineral oil or paraffin oil.The ER effect can be enchanced by the addition of small polar molecule aniline.But the leakage current density of the fluid will also be increased with increasing of the aniline content.
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发布时间：2021-03-19 - 摘要：A new biocompatible copolymer,poly(dimethyl siloxane) graft poly(ethylene oxide) heparin(PDMS g PEO Hep) was prepared by the condensation between the hydroxyls of poly(dimethyl siloxane) graft ω hydroxyl poly(ethylene oxide) and heparin using dicyclohexylcarbodiimide(DCCI) as a dehydrating agent The IR spectrum of the product showed a weak peak at 1735 cm-1 ascrided to the ester groups The surface heparin content and activity were investigated by Toluidine Blue Heparin Assay(TBHA) and Thrombin Time Test (TTT). The polymer exhibited high surface heparin content and activity,Finally,the in vitro antithrombogenictity of glass surfaces coated with PDMS-g-PEOHep was assessed initially using Recalcification Time Test (RTT) and Prothrombin Time (PTT).The results indicated that PDMS-g-PEO-Hep showed expected blood compatibility and could be used as coating antithrombogenic materials.
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发布时间：2021-03-19 - 摘要：α,ω bis(γ aminopropyl)polydimethyldiphenyl siloxane prepolymer (APMPS)was synthesized by ring opening copolymerization of octamethylcyclotetrasiloxane,hexaphenylcyclotrisiloxane and 1,3 bis(γ aminopropyl)tetramethyldisiloxane with potasium silanolate as catalyst.The chemical structure and some properties of the APMPS were also investigated via UV、IR、 1H-NMR and GPC methods.
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发布时间：2021-03-19 - 摘要：Electrorheological (ER) fluids with high ER activity were based on polyaniline (PAn) composite particles,which were prepared by surface modification of partially dedoped PAn particles using blending with poly (vinyl alcohol) (PVA),poly (methyl methacrylate) (PMMA),or polystyrene (PSt),or graft copolymerization with acrylamide The effects of structure of PAn composite particles on properties of the PAn based ER fluid were studied.The results showed that the PAn based ER fluid might be improved significantly when PAn particles were coated by PVA or grafted by polyacrylamide at a certain value,while PMMA or PSt coating of PAn composite particles would cause both static yield stress and leak current density for the ER fluids to decrease.It was suggested that composite particles may improve ER performance when the composite particles with strong interaction between PAn and insulative coating were appropriately designed,for example,insulative coating forms hydrogen-bonding or chemical bonding with particles.
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发布时间：2021-03-19 - 摘要：The present work studies the effect of interfacial adhesion on the brittle ductile transition (BDT) in PVC/NBR by strengthening the interfacial adhesion through an increase of the acrylonitrile (AN) content in NBR The rubbers,NBR18 and NBR26,consist of 18 and 26 wt % of AN,respectively There are two BDT master curves for PVC/NBR blends,when impact strength ( S I ) is plotted against matrix ligament thickness ( T=T(d,σ,φ ),where d is the NBR particle diameter, σ the dispersity of particle diameter,and φthe volume fraction of dispersed phase,respectively.)Below the critical value Tcof T,the blend becpmes extremely tought.At any given T the SI of PVC/NBR26 is lower than that of PVC/NBR18,and the transition in PVC/NBR26 occurs at a lower T value,indicating that strong interfacial adhesion is not favorable for achieving high toughness.The stress whitening zone and SEM photograph of fracture of the samples shows that,as interfacial adhesion is too strong,interfacial debonding and hence cavitation is hindered,thereby delaying the occurrence of shear yield deformations.
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发布时间：2021-03-19 - 摘要：A series of main chain liquid crystal line aromatic copolyesters with T shaped and rod shaped mesogenic units were synthesized via solution condensation polymerizations from 4,4′ ( α,ω decanedioyloxy) dibenzoyl dichlorides with 2 (4′ ethoxy phenyl) hydroquinone and diphenol.All of the copolyesters showed thermotropic liquid crystalline behaviors as detected by using DSC,polarized microscopy and X ray diffraction.Their melting points (T m ) and isotropization temperatures ( T i ) change regularly with varying the diphenol unit content in the copolymer.
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发布时间：2021-03-19 - 摘要：New biodegradable Poly(terephthalyl tyrosine ester amide)carbonates were synthesized from tyrosine derived diphenols and phosgene in dichloromethane using pyridine as acid acceptor.Their chemical structures were confirmed by 1H-NMR,FT IR and elemental analysis.The physical properties of the polycarbonates could be modulated by the use of different tyrosine esters.The in vitro degradation and drug release profile of 5 fluorouracil and bovine serum albumin were also studied.
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发布时间：2021-03-19 - 摘要：Waterborne emulsions of lightly sulfonated polystyrene ionomer(SPS) were prepared by neutralizatioin with ammonia liquor and addition of water.The principle of emulsification was explained.The aggregated structure of SPS chains in organic solvents was discussed.SPS molecule chains can form a type of microionic lattice.The variations of the conductivity and viscosity of SPS ionomer solution during the emulsification process were studied.The emulsification process and phase inversion were characterized by using the variation of conductivity and viscosity.The emulsification process included the dissociation of the microionic lattices and aggregation of the hydrophobic segments.The aggregated structure of SPS ionomer chains in solvents varied with the variation of polar of solvents were studied and affected the emulsification process.The mechanism of the phase inversion was discussed.The effects of solvent polarity and ionic contents on the emulsification process were studied. The stability of emulsion were much affected by the ionic contents.The particle size increased with the decrease in ionic contents.
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发布时间：2021-03-19 - 摘要：Two new monomers,4 methylene 2 styryl 1,3 dioxolane and 4 methylene 2 styryl 2 methyl 1,3 dioxolane were synthesized.Their free radical and cationic polymerizations were investigated.The structures of the obtained polymers were characterized based on their IR, 1H and 13 C NMR data.The polymerization mechanisms were proposed upon the structures of the polymers obtained.The effects of 2 substituted groups in the 1,3 dioxolane ring on the polymerization and mechanism were discussed...
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发布时间：2021-03-19 - 摘要：Light transmission spectra of THF solutions of poly(C60 co methyl methacrylate)s and poly (C60 co styrene)s continuously red shift with increasing concentration.Formation of fullerene nanoclusters may be responsible for the unusual spectral shift with concentration.It has long been scientists′ dream to “tune” material′s properties by simple means,and the C60 containing polymers represent such a group of novel materials whose optical properties are predictably and reversibly tunable by a simple change in concentration.
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发布时间：2021-03-19 - 摘要：Ring opening copolymerizations of 1,4 dioxanone (DON) and polyethyleneglycol (PEG) were carried out with stannous octoate (Sn(Oct)2) as a catalyst to prepare block copolymer (PDON-b-PEG-b-PDON).The results of 1H-NMR spectrochemical analysis showed the composition of block copolymers could be adjusted by varying the feeding ratio of PEG and DON.The Tm and crystallinity of PEG block in the block copolymers decreased greatly with the increase of PDON content.The water absorption percentage of block copolymer was also improved compared with that of PDON.
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发布时间：2021-03-19 - 摘要：Narrowly distributed spherical microgel particles of poly(N isopropylacrylamide) (PNIPAM) were prepared by emulsion polymerization in water.The volume phase transition of the microgel particles was studied by static and dynamic laser light scattering.The results were compared with the coil to globule transition of individual long linear PNIPAM chains.The microgel particles have a higher transition temperature,but a less sharp phase transition in comparison with that of long linear chains.This difference has been attributed to both the short length and the broad length distribution of the subchains inside the microgels.A combination of static and dynamic laser light scattering results revealed that even in a highly collapsed state the microgel particles retained～70%of water and the density of the microgel networks increased from 0.021g/ml to ～0.3g/ml during the phase transition.The phase transition of the microgel particles is continuous,in cintrast to the discontinuous volume phase transition in bulk PNIPAM gels.The microgel particles are thermodynamically stable even at their collapsing limit.The behavior of microgel particles in comoared with that of individual PNIPAM chains.
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发布时间：2021-03-19 - 摘要：Two new methods have been developed for investigating the Young′s modulus and thermal conductivity of ultra oriented gel polyethylene films with draw ratios between 1 and 200.The laser generated ultrasonic pulse method gives the Young′s modulus in the draw and transverse direction,while the pulsed photothermal radiometry method gives the thermal conductivity in the draw,transverse and thickness direction of the film.The axial Young′s modulus is found to increase sharply with increasing draw ratio while the transverse modulus shows only a slight decrease.The thermal conductivity exhibits a similar behavior.At λ=200,the axial Young's modulus is about 80%of that of steel while the axial thermal conductivity is about twice that of steel. The great increases in the axial modulus and thermal conductivity arise form the presence of needlelike extended chain crystals (crystalline bridges). We propose a structural model which treats the crystalline bridges as the fiber phase of a short-fiber composite.This model provides a good description of the behavior of the axial Young's modulus and thermal conductivity.
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发布时间：2021-03-19 - 摘要：The isotropy or anisotropy in some physical properties of the amorphous poly(ethylene terephthalate) films uniaxially drawn at temperatures above its T g and then quenched to room temperature have been studied.Experimental results here presented show that this amorphous state of high global chain orientation but nearly random segmental orientation,the GOLR state,is nearly isotropic in refractive indices and Young′s modulus for small deformation,while it is very probably anisotropic in thermal conduction and microwave dielectric properties.
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发布时间：2021-03-19 - 摘要：A new catalytic system composed of anhydrous rare earth chloride and 50% fuming sulfuric acid has been developed for the homopolymerization of tetrahydrofuan (THF) and the copolymerization of THF with chloromethyl thiirane (CMT).The polymerization characteristics of THF were examined.White solid PTHF with high conversion of 65% and high viscosity molecular weight of 10,000～15,000 can be obtained at 0 to -15℃ in about 5 hour.The molecular chain of PTHF has average two hydroxyl groups.The effects of copolymerization parameters such as temperature,duration and comonomer ratio on the copolymerization of THF with CMT were studied.
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发布时间：2021-03-19 - 摘要：The reactive processing process of a novel crosslinkable epoxy thermoplastics (CET),Epoxy terminated Poly(phenylene ether ketone) was studied.Five process models were established.The cure cycles of continuous carbon and glass fiber reinforced E PEK were optimized based on the above process models.It has been proved that the approach introduced here has demonstrated the potential of practicality and reliability in cure cycle design and of improved prediction and control of the properties of the finished products.
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发布时间：2021-03-19 - 摘要：The structure and properties of poly(acrylamide acrylic acid)[P(AM-AA)]/poly (acrylamide dimethyldiallyammonium chloride)[P(AM-DMDAAC)] complex solution formed through Coulomb force were studied by means of dynamic light scattering,viscosity and transmittance measurements.The results show that conformation and hydrodynamic radius of the complex in solution are mainly affected by such factors as composition of the complex solution,polymer concentration,and NaCl content.Proper interaction between P(AM-AA)and P(AM-DMDAAC)results in a complexed homogeneous solution where,compared to the constituents,the paired polyelectrolyte molecules have more expanding conformation and larger hydrodynamic radius and,therefore,the comolex solution has higher viscosity.While too strong interaction between P(AM-AA) and P(AM-DMDAAC)or screening effect of NaCl on complexation of P(AM-AA)with P(AM-DMDAAC) result in a more compact or a more coiled complex structure,leading to a reduction in hydrodynamic radius of the complex and hence a decrease in solution viscosity.
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发布时间：2021-03-19
Research Article
- 摘要：A polymer containing electron accepting chromophore,i.e.poly (N4-cyanophenyl acrylamide) was synthesized.When C60 was added to the solution of P(CPAA),the fluorescence intensity of the latter was decreased regularly.An upward curvature was found in the Stern Volmer plot,which indicated not only the formation of exciplex but also the formation of charge transfer complex in the ground state (CTC).Both mechanisms of charge transfer were verified by the measurement of fluorescence life time and UV absorption spectra,respectively.The eletron-accepting ability of C60 was tested to be almost as strong as that of DMT,which was compatible with their ionization potentials.
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发布时间：2021-03-19 - 摘要：Bulk copolymerization of styrene (St, M 1)with β hydroxy ethyl acrylate (HEA, M 2)were carried out at 60,80.100,120 and 140℃ at two sensitive feed compositions.Compostions of copolymers were analyzed by elemental analysis (EA).The relative reactivity ratios were calculated by Error in Variable method (EVM) to be (r1=0.313, r2=0.224),(0.349,0.225),(0.409,0.291),(0.525,0.327) and (0.565,0.347) at different temperatures.The differences of activation energies,entropies,and ethalpies between homopropagation and cross-propagation,were calcutated too.
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发布时间：2021-03-19 - 摘要：Based on factors favoring the fibrillation of thermotropic LCP(TLCP) in resin melts,the spinnability of TLCP and the viscosity ratio of TLCP to matrix resins,a hybrid polyethersulfone composite has been injection molded.This composite is reinforced by CF with diameters of microns and TLCP fibrils with diameters of 50～300 nanometer and aspect ratios up to 30.All the decreased apparent viscosity of melts,the increased CF aspect ratios in the matrix and the enhanced tensile properties of molded samples show that the processability,the reinforcing effect and the performances of this composite have been improved by the added TLCP.These results indicate that a combination of the concept of insitu composite and the principle of hybrid reinforcing with reinforcements of different diameters is effective for the processing and application of advanced engineering plasites.
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发布时间：2021-03-19 - 摘要：Highly active syndiotactic specific catalyst for the polymerization of styrene are obtained by mixing Cp*TiMe3 with +[B(C6F5)4] - in the mole ratio 1∶1,producing 97.5% syndiotactic PS at an activity of 1.15×106gPS/molTi·h.Treatment of [Cp*TiMe3] with +[B(C6F5)4] - results in the formation of [Cp*TiMe2] +[B(C6F5)4] - complex,which is a good source in solution of the cationic species [Cp*TiMe2] +.Both activity and syndiospecificity of the “cationic” catalyst are no less than the CpTi(OBu)3/MAO and CpTi(OPH)3/MAO catalysts,but are much more active than Cp*TiMe3/MAO as well as Cp*TiCl3 /MAO.The cationic catalyst is a very effective catalyst precursor for the Ziegler-Natta polymerization of styrene to syndiotactic polystyrene at temperatures≥-10℃,while the "cationic"contributes to promoting the polymerization of styrene to atactic polystyrene at temperatures≤-20℃.The molecular weight (Mw of sPS increases with the decrease of the temperature,suggesting that lower temperature contributes to reducing the chain transfer and increasing the life of the active species for chain propagation.The Tm of the sPS polymerized at -10～70℃ is almost constant.The styrene polymerization behaviors were essentially insensitive to the dielectric constant of the polymerization medium.
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发布时间：2021-03-19
Research Bulletin
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