最新刊期
卷 ， 期 3 ， 2012
- 摘要：Acrylonitrile(AN) homopolymerization and the copolymerization were examined under various conditions in the presence of anhydrous magnesium chloride (MgCl2).The polymers were obtained with high isotacticity.The effect of solvents,reaction temperature,the molar ratio of MgCl2 and AN on AN homopolymerization and the copolymerization and the tacticity of the polymers were investigated.The optimum reactive conditions to obtain the polymers with high isotacticity are as follows:hexane as the solvent,2,2'-azobisisobutyronitrile (AIBN) as the initiator,the temperature of 60℃ and the molar ratio (MgCl2/AN) of 2 ∶1.The effects of monomer concentration and initiator concentration on the AN homopolymerization,AN/IA(itaconic acid) copolymerization,AN/IA/MA(methylacrylate) copolymerization were investigated.The homopolymers and copolymers with highly triad isotactic content (30.2%～55.9%) have been obtained.The polymers were characterized by 13C-NMR and Fourier transform infrared (FTIR) spectra.At the same time,the thermal properties of the polymers were characterized by differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA).The DSC results show that the exothermic peak temperature of the copolymers increases with the degree of isotacticity,as well as the exothermic peaks of copolymers become wider.The TGA results reveal the copolymer with high isotacticity shows rapid weight loss when the temperature is higher than approximately 300℃,the char-yields and thermal stability of the copolymers are decreased with the increasing of the degree of isotacticity.关键词：Anhydrous magnesium chloride;Polyacrylonitrile;Isotacticity;Thermal analysis
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发布时间：2021-03-19 - 摘要：The macromolecular brushes,PI-g-P(TFEMA-co-HEMA-tms) was synthesized via atom transfer radical polymerization(ATRP),using polyimide with bromide side-group (PI-Br) as the macroinitiator and 2,2-bipyridine/CuCl as catalytic system,trifluoroethyl methacrylate (TFEMA) and 2-(trimethylsilyloxy)ethyl methacrylate (HEMA-tms) as the comonomers.PI-g-P(TFEMA-co-HEMA) with hydroxyl group in its side chains was generated by removing of trimethylsilyl groups under mild acidic condition.Finally,PI-g-P(TFEMA-co-HEMA-P) with phosphite groups (P) in its side chains was further synthesized by reaction between hydroxyl group of side chains,PHEMA and diethyl chlorophosphate.The structure of the resultant brushes was verified by1H-NMR,FTIR et al.Differential scanning calorimetry (DSC) and thermogravimetry analysis (TGA) were used to evaluate the thermal properties of the resultant macromolecular brush.The results show that PTFEMA chain segments decompose at around 120℃,and the PHEMA chains decompose at about 250℃,while the decomposition of PI backbone is over 425℃.The structure composition of the brush PI-g-P(TFEMA-co-HEMA) analyzed from TGA has a good agreement with the result calculated from 1H-NMR.The solubility tests indicate that the composition of the side chain has significant influence on the solubility of the brush.
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发布时间：2021-03-19 - 摘要：3-Glycidoxypropyltrimethoxysilane (GPS) was first used as a coupling agent to react with SiO2 nanoparticles to yield the modified SiO2 nanoparticles with epoxy groups on the surface of the nanoparticles (SiO2-GPS).In order to obtain the amine-riched SiO2 nanoparticles on the surface,hyperbranched poly-(ethylene imine) (HPEI) was mixed with SiO2-GPS and then a reaction occured between epoxy groups and amine groups,resulting to a poly(ethylene imine) grafted SiO2 nanoparticles (SiO2-GPS-g-HPEI).Subsequently,SiO2-GPS-g-HPEI was added into a blend of polypropylene and polyproplyene- grafted -maleic anhydride (PP/PP-g-MAH) to enhance the strength of PP.The modified SiO2 nanoparticles were characterized by Fourier transform infrared spectroscopy (FTIR),thermo gravimetric analysis (TGA) and scanning electron microscopy (SEM),respectively.The results showed that GPS and HPEI had been grafted onto the surface of SiO2 nanoparticles,which had well dispersity in matrix of PP.After blending by Haake Rheomix600 OS viscometer,the blend was molded into a sheet by compression,and testing specimens were cut from the molded sheets by a die cutter.The samples were characterized by tensile strength and notched impact strength.The results of scanning electron microscopy (SEM) revealed the tough fracture.The torque curve of ternary blending (on behalf of the viscosity) was increased,indicating that the reaction happened in blending.The notched impact strength of PP/PP-g-MAH increased by 96.3% compared to pure PP after adding 2% SiO2-GPS-g-HPEI.Moreover,tensile properties of the nanocomposites were also enhanced.关键词：Nanocomposites;Modification of SiO2;Modification of PP;Mechanical properties
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发布时间：2021-03-19 - 摘要：Micron-sized silica gel particles were chemically surface-modified with coupling agent KH-590,mercapto groups were introduce onto the surfaces of silica gel particles,and a redox initiation system of mercapto group-cerium (Ⅳ) salt was constructed.On this basis,the highly effective graft-polymerization of acrylonitrile on surfaces of silica gel particles was explored successfully,and the grafted particles SiO2-MPMS-g-PAN with a high grafting degree of 30 g/100g were obtained.The grafted particles SiO2-MPMS-g-PAN were characterized by FTIR,TGA and SEM methods.The effects of the main factors on the graft polymerization of AN were examined.The experimental results show that mercapto group-cerium (Ⅳ) salt system is similar to hydroxyl group-cerium (Ⅳ) salt system,and it can effectively initiate the vinyl monomers to be graft-polymerized on the surfaces of solid particles.As compared with the method of grafting through,the graft polymerization initiated by cerium (Ⅳ) salt has the character of high graft efficiency because the active sites lie on the surface of the support,and it is a highly effective method of surface-initiated grafting.In order to prepare the grafted particles SiO2-MPMS-g-PAN with high grafting degree in this system,the suitable H+ concentration should be 0.25 mol/L,and the appropriate cerium (Ⅳ) salt concentration should be 5.010-3 mol/L.At the same time,the graft polymerization should be allowed to carry out at 50℃.关键词：Mercapto group;Cerium (Ⅳ) salt;Redox initiation system;Surface-initiated grafting;Acrylonitrile
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发布时间：2021-03-19 - 摘要：Micro-sized silica gel particles were first surface-modified with coupling agent -aminopropyltrimethoxysilane (AMPS) for obtaining the modified particles SiO2-AMPS,on which primary amino groups were chemically attached.Subsequently,the Schiff base reaction between SiO2-AMPS particles and 4-(diethylamino)salicylaldehyde (DEAS) was allowed to carried out,resulting in the modified particles SiO2-DEAS,on which aryl tertiary amine moieties were bonded.So a redox initiation system was constituted with the aryl tertiary amine moieties on the surfaces of SiO2-DEAS particles and benzoyl peroxide (BPO) in a solution,and the surface-initiated grafting of styrene(St) was realized,and the grafted particles SiO2-DEAS-g-PSt with a high grafting degree of 27 g/100g were prepared.The grafted particles SiO2-DEAS-g-PSt were characterized by FTIR,SEM and TGA.In this work,the effects of some factors on the graft-polymerization of styrene were mainly investigated.The experimental results show that the graft-polymerization initiated by aryl tertiary amine-BPO system has the character of high grafting degree because of the lying of active sites on the surfaces of the support particles as compared with the method of grafting through,in which the polymerizable double bonds are first introduced onto the surfaces of the solid particles.For those oil-soluble monomers,this is a surface-initiated grafting method with a high efficiency.In order to prepare the grafted particles SiO2-DEAS-g-PSt with a high grafting degree,50℃should be selected as an suitable reaction temperature,a amount of BPO with 3 wt% of the monomer mass should be selected as an appropriate used amount of BPO in the solution,and the applicable monomer concentration is 10 wt% of the solution mass.关键词：Polystyrene;Redox initiation system;Aryl tertiary amine;Surface-initiated grafting;Silica gel
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发布时间：2021-03-19 - 摘要：The stress relaxations of HNBR were studied by molecular dynamics (MD) simulation.The structure of hydrogenated nitrile butadiene rubber (HNBR) was constructed and several circles of energy minimization (MM) and MD simulation were applied.The distribution function of gyration radius was calculated under different compression ratios and temperatures.The fitting functions of normal stress with time under different pressures were obtained.Compression stress relaxation experiment of different compression ratios was also conducted.Comparing with the coefficient of stress relaxation from the experiment,it was found that the theoretical stress relaxation curves were similar to the experimental data.The results indicated that the mean-square radius of gyration decreased with the enhancement of pressure and it decreased with the reduction of temperature,which corresponded to the typical viscoelasticity stress relaxation behaviors of polymers.It is confirmed that the variation of mean-square radius can be used to quantitatively describe the stress relaxation of rubber system and a good agreement between the theoretical curves with the experimental data can be obtained from MD simulation.关键词：Molecular dynamics simulation;HNBR;Mean square radius of gyration;Stress relaxation
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发布时间：2021-03-19 - 摘要：A polyimide containing phthalein groups and hydroxyl side-groups was synthesized.In the synthesis,a new diamine monomer containing phenolphthalein group was prepared by nitrification of phenolphthalein and followed with further reduction.The polyimide was obtained by polycondensation of the diamine monomer with 4,4-hexafluoroisopropylidinedi(phtalic anhydride) (6FDA) and subsequent high temperature imidization step.The chemical structure of the monomer and polyimide was characterized by 1H-NMR and FTIR.GPC test gives the molecular weight (Mn) and polydispersity of the polyimide of 15500 and 2.47,respectively.The polyimide shows no obvious Tgin the range of 100～350℃ and a Td of 388℃ with 2.5% mass loss by thermal analysis (DSC and TGA).The polymer has good solubility in some aprotic polar organic solvents such as DMF,DMAc, etc. but is insoluble in weak polar organic solvents such as toluene.The UV-Vis transmittance and absorbance spectra show that the polyimide possesses good optically transparency in the visible region.For its aromatic hydroxyl side-groups containing structure,the polyimide can be further used as a precursor of high performance functional materials.关键词：Polyimide;Phenolphthalein;Thermo stability;High transparency
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发布时间：2021-03-19 - 摘要：The flocculation performance of isodose anionic polyacrylamide (PAM) with different parent solution concentrations (c) for ferric oxide suspension was investigated.It is found that the flocculation performance of PAM could be improved and impaired with the increase of cpemp.Moreover,the concentration of 0.3 g/L is the optimal parent solution concentration (cop) of PAM.Through scaling theory analysis and rheological measurements, cop is proved to approach the critical entanglement concentration (ce).Conductivity test results of PAM parent solution and the conductivity varieties of stirring water added PAM reveal that there exits a charge shielding phenomenon when cp is above cop.The number of PAM effective charges decreases due to the charge shielding,which deteriorates PAM flocculation performance.On the other hand,the flocculation performance of dilute PAM solutions can be enhanced in case of mixing dilute PAM solutions with appropriate amount of -cyclodextrin (CD).There exists intermolecular hydrogen bond between PAM and -CD,which makes several PAM molecules bridged by one -CD molecule.The observed variations of flock sizes and flocculation performance after PAM being bridged can explain the reason of the poor performance for dilute parent solutions,that is,PAM could hardly form flock with ample size and sedimentate sufficiently because the molecules are relatively isolated when the parent solution concentration is below cop.关键词：Polyacrylamide;Flocculation performance;Parent solution concentration;Effective charge
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发布时间：2021-03-19 - 摘要：A well-ordered honeycomb structure of single component polylactide (PLLA) films was prepared via breath figure method.Their pore structure and morphology were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM).The effect of factors,such as solvent type,PLLA concentration,temperature,relative humidity and spreading volume,on the pore patterns was investigated.The results showed that high humidity and optimal PLLA concentrations were necessary for preparing the honeycomb porous PLLA films.Compared to CHCl3,CH2Cl2 with higher vapor pressure favored the formation of more regular honeycomb porous structure.The pore size of PLLA films increased from (1.750.24) m to (11.501.43) m with increasing relative humidity from 43% to 91%.Instead of the formation of three-dimensional honeycomb pore structure,a single layer pores with depth of ca.1.8 m was formed on the film surface.The optimum preparation conditions for the honeycomb structured PLLA films were:solvent CH2Cl2,relative humidity 75%,temperature 34℃,spreading volume 80 L and PLLA concentration 3 wt%.A possible mechanism was proposed.Due to the homeycomb porous structure,this special PLLA films would be in favor of cell adhesion and growth.Thus they are expected to be a very promising tissue engineering scaffold.关键词：Polylactide;Breath figure;Honeycomb structure
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发布时间：2021-03-19 - 摘要：Self-assembled poly(aniline-co-pyrrole) (PACP) hollow spheres were prepared via dilute polymerization under an unstirred condition using ammonia as a polymerization medium.The morphology of the PACP copolymers was studied by choosing several important parameters such as stirring condition,comonomer molar ratio,synthetic media and polymerization time.The morphology,structure and properties of the PACP copolymer spheres were characterized by scanning electron microscopy,transmission electron microscopy,FTIR,wide angle X-ray diffraction,thermogravimetric analysis and four-probe technique.It was found that the above-mentioned polymerization conditions had important influence on the morphology of the PACP copolymers.The polymerization parameters could be used to guide the PACP copolymer morphology from flower-like structures to hollow spheres in polymerization process.Uniform self-assembled PACP copolymer hollow spheres with outer diameter and shell thickness of 610～863 nm and 144～162 nm,respectively,formed under the optimal polymerization conditions of an unstirred condition,comonomer concentration of 0.05 mol/L in ammonia solution for 24 h.Moreover,the Ag(Ⅰ) ions adsorbability of the PACP copolymer spheres was examined.TEM and wide angle X-ray diffraction results showed that silver nanoparticles with 10～30 nm size were homogeneously dispersed in the PACP copolymer hollow spheres after adsorption,indicating that the copolymer spheres would had reactive adsorbability of Ag(Ⅰ) ions.关键词：Poly(aniline-co-pyrrole);Self-assembly;Hollow spheres;Dilute polymerization;Adsorption property
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发布时间：2021-03-19 - 摘要：Thermo-sensitive poly(N-isopropylacrylamide) (PNIPAM) hydrogels were prepared by UV-initiated photopolymerization and used as the cladding layer for thermal-sensing based on the long-period fiber grating (LPFG).In the reaction,N,N-methylenebisacrylamide was used as crosslinker,benzoin dimethyl ether as initiator.The characteristics of the hydrogels were investigated with FTIR,DSC and TG.The effect of the crosslinking agent content on the swelling ratio was also investigated.The results indicated that the crosslinking agent content had a significant influence on the swelling ratio.A LPFG sensor was designed by utilizing the PNIPAM hydrogel as a sensitive cladding coating.For the preparation,a thin-film of the PNIPAM hydrogel was deposited on the LPFG using the dip-coating technique.Changes in temperature and the relative humidity (RH) cause variation of the spectral characteristics of the LPFG in both the resonant wavelength and the minimum transmission.Following the study to establish an optimized coating,the effect of the temperature and the RH variations on the performance of the sensor was investigated.The experimental results showed that the thin film parameters (thickness and refractive index) were directly related to the sensitivity of sensors, and the LPFG coated with PNIPAM hydrogel showed sensitive response to the temperature variation.Combining the advantages of film sensors and fiber optical sensors,the hydrogel-coated LPFG sensors have application prospects in different areas.关键词：N-isopropylacrylamide;Hydrogel;Long-period fiber grating;Sensor;Thermo-sensitive
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发布时间：2021-03-19 - 摘要：This paper analyzed rheologic properties of solutions of partially hydrolyzed polyacrylamide with super high molecular weight by rotate rheometer.The distribution of hydrodynamic diameter of polyacrylamide in brine solutions of different concentrations was measured by dynamic light scattering.The approach to accurately characterize the weight average molecular weight (Mw),mean square radius of gyration (Rg) and the virial coefficient (A2) of polyacrylamide with super high molecular weight for oil recovery by multiangle light scattering (MALS) was studied.These three parameters of a commercial polyacrylamide sample (FP3630S) for oil recovery were precisely measured as Mw= (1.330.06)107,Rg=(2025) nm and A2 =(2.130.08)10-3 cm3 mol /g2,respectively.关键词：Multiangle light scattering;Molecular weight;Polyacrylamide for oil recovery;Rotate rheometer
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发布时间：2021-03-19 - 摘要：A new kind of supramolecular polymer can be obtained through hydrogen bond interactions of UPy (2-ureido-4[1H]-pyrimidone) units.So it is a new method of polymer modification.Inspired by this,a new kind of polyurethane with UPy units in the main chain was designed.A novel polyurethane chain extender containing UPy units was synthesized through five steps.UPy units were introduced into the main chain of the polyurethane through reacting OH groups with the NCO groups in the prepolymer.The structure was characterized by FTIR and 1H-NMR.The thermal testing results showed that the UPy units aggregated to form microcrystals which melted around 60℃ in the polyurethane.The polyurethane with UPy units in the main chain showed greatly improved mechanical performances compared to the non-UPy counterpart in the tensile testing.The breaking strength was up to 28.6,17.3,15.5,14.9 MPa by using PTMG650,1000,1400,2000 as the soft segment.UPy content in the PU can be adjusted through changing the molecular weight of the soft segment to get PU elastomers with proper performance.关键词：UPy;Quadruple hydrogen bond;Supramolecular chemistry;Polyurethane;Chain extender
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发布时间：2021-03-19 - 摘要：Non-oriented poly(phenylene sulfide) fibers with different crystallinity were prepared by melt spinning and heat treating.Based on the measurement of density and sonic velocity,intrinsic horizontal sonic modulus of amorphous and crystalline phases of PPS fibers was determined to be 1.99 GPa and 4.40 GPa,respectively.Based on Samules's model and measured crystallinity and X-ray azimuth scanning,the Hermans orientation factor of amorphous phase of PPS fibers made at different drawing and heat-setting conditions was determined.The relationship between tenacity and processing conditions was discussed based on the above structure parameters.The work shows that the optimum stretching and setting temperature of PPS fiber is near 90℃ and 190℃ separately.The increasing of stretching and tense setting temperature is beneficial to the improvement of the fiber's crystallinity and is helpful to the promotion of fiber's tenacity within certain range.But the over rising of the processing temperature will be disadvantageous to fiber's amorphous orientation and thus reduce the tenacity.The increasing of stretching multiples will improve the amorphous orientation of the fiber and furthermore improve the tenacity of the fiber.关键词：Poly(phenylene sulfide) (PPS);Sonic velocity;Intrinsic transverse sonic modulus;fam
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发布时间：2021-03-19 - 摘要：A novel two color white light-emitting poly(aryl ether) (P1) containing blue unit and orange unit in the side chains was synthesized by a facile,metal-free condensation polymerization,and then P2 and P3 were synthesized by introducing the light blue dopant (BCzVF) into P1's side chain.We studied solubility,thermal properties,electrochemical properties,optical properties and electroluminescent properties of the polymers.The results reveal that all the polymers have good solubility and high decomposition temperature,there are efficient energy transfer from deep blue unit to light blue unit and orange unit in solid film,and the PL spectra are almost same before and after annealing indicating their excellent spectral stability.Based on the single-layer device structure of (ITO/PEDOT:PSS/Polymers/Ca/Al),white EL with simultaneous blue and orange emission was observed and was attributed to the partial energy transfer and charge trapping from the blue host to the orange dopant.The best device performance with a luminance efficiency of 7.96 cd/A,a maximum brightness of 9950 cd/m2 and CIE coordinates of (0.33,0.44) was achieved.关键词：WPLED;Poly(aryl ether)s;Energy transfer;Electroluminescence
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发布时间：2021-03-19 - 摘要：Poly(p -phenylene sulfide) (PPS) and multiwall carbon nanotubes (MWCNTs) were melt blended into composites which were melt spun into PPS/MWCNT composite fibers.The dispersion state of MWCNTs in polymer matrix,interfacial interaction between MWCNTs and polymer matrix,crystallization behavior and mechanical properties of composite fibers were carefully investigated by scanning electron microscopy (SEM),Raman spectroscopy,differential scanning calorimetry (DSC),dynamic mechanical analysis (DMA) and tensile properties testing.And the relationship between microscopic structures and macroscopic properties was explored.The experimental results show that good dispersions as well as well-bonded interfaces between polymer matrix and MWCNTs were obtained in the composite fiber due to the - stacking interactions between PPS and MWCNTs.The well-dispersed MMCNTs showed an efficient nucleation ability for PPS matrix.The stretching during melt spinning was benefit for disaggregation of MWCNTs in PPS matrix and orientation of MWCNTs along the stretching direction.As evidenced by Raman spectra,stretching during melt spinning promoted the interfacial - stacking interaction effectively and realized the interfacial enhancement in composites.,finally resulting in a great improvements of mechanical properties of fibers.When the content of MWCNTs increased to 5 wt%,the storage modulus was greatly improved and the tensile strength of fibers was increased by 220% compared with that of pure PPS fibers.关键词：Poly(p-phenylene sulfide);Multiwalled carbon nanotube;Composite fibers;Mechanical reinforcement
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发布时间：2021-03-19
Research Article
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