最新刊期
卷 ， 期 7 ， 2009
- 摘要：Cellulose whisker (CW) was prepared by hydrolysis of natural microcrystalline cellulose(MCC) with sulfate acid.The NR/CW composite was prepared by natural rubber (NR) latex coagulated with CW suspension.The results show CW has well reinforcement effect to NR.The modulus,elongation at break,tear strength of NR composites are further improved by using CW modified by resorcinol (R) and hexamethylene tetraamine (H).The mechanical properties of hot air aging (100℃,72 h) of NR/CW composite vulcanizates are markedly superior to those of NR.The tensile strength of NR/RH-CW composites was dropped from 28.54 MPa to 21.78 MPa,the rate of change was down to 23.7%,and the elongation at break decreased from 594% to 493% and the change rate decreased to 17.0%.The tensile strength of pure NR was dropped from 22.02 MPa to 2.40 MPa,and the change rate was 89.1%;and the elongation at break was dropped from 579% to 168% and the change rate was 71.0%.SEM photo shows the interface compatibility between RH-CW and NR matrix was improved in comparion with CW and NR.TGA results show the 5% weight loss temperature of composites is decreased and the residue increases with CW adding.In addition,there is a peak of the derivative TGA curve at 520℃,and the peak becomes larger and the residue increases with RH-CW adding.
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发布时间：2021-03-19
Rapid Communications
- 摘要：The research on nickel complexes has provided the great potentials of new catalysts for ethylene reactivity (oligomerization and/or polymerization).In addition to studying the mechanism of catalytic ethylene reactivity,nickel complex catalysts provide the fundamental bases of model catalysts,which present certain catalytic performance including catalytic activity,selectivity for oligomer or polymer,polymer properties and so on.The well modified model catalysts and newly designed ones would pave the way for potential industrial processes.Moreover,nickel catalysts are found to be relatively easier to conduct β-hydrogen elimination and therefore they would make chances of getting novel branched polyethylenes with some advantage properties for further application.Fundamental research makes the future of industrial catalysts.The progress of nickel complexes as catalysts for ethylene reactivity are reviewed,and the intrinsic relationship between catalyst structure and corresponding catalytic performance is highlighted in this paper.
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发布时间：2021-03-19
Reviews
- 摘要：Poly(butadiene-styrene) rubber latexes (SBRL) modified by poly(n-butyl acrylate)(PBA) were used as seeds (SBA),then SBA/PVC composite resins were prepared through seeded emulsion copolymerization with vinyl chloride monomer.Diameter distributions,morphological structure of the latex particles and morphology of composite materials were characterized with the aid of particle diameter analyzer and transmission electron microscope (TEM).Dynamic mechanical properties of the samples and breaking surfaces’ morphology of the notched bars were determined and characterized via a dynamic mechanical analyzer (DMA) and scanning electron microscope(SEM),respectively.TEM and particle diameter analysis showed that the PVC was assuredly coated onto the SBA particles,and the SBA/PVC particles presented clearly core-shell morphology.TEM studies indicated that the composite particles of the SBR modified by the PBA were uniformly dispersed in the PVC matrix.DMA results revealed that the SBA/PVC sample showed a weak and extensive glass-transition in low-temperature range.It was suggested that there should be a transition layer of microstructure where the SBA-grafted PVC macromolecules were embedded.The mechanical properties’ research showed that the SBA/PVC composite resin had good impact strength at a low level of the PBA.SEM studies showed that the fractured surface of the composite sample exhibited better toughness than that of the SBR/PVC sample.
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发布时间：2021-03-19 - 摘要：The copolymerization of glyceryl methacrylate (GMA) and methyl methacrylate (MMA) was performed in a suspension polymerization system using ethylene glycol dimethacrylate (EGDMA) as crosslinker,resulting in the crosslinked microspheres GMA/MMA. Via ring-opening reaction,polyethylene glycol (PEG) was grafted onto the surfaces of microspheres GMA/MMA in the coupling graft manner,the immobilization of PEG was realized,and a kind of phase-transfer catalysts PEG-GMA/MMA,namely,triphase catalyst,was prepared.The effects of various factors on the grafting reaction of PEG were studied,and the reaction mechanism was investigated.The experimental results show that the immobilization of PEG on microspheres GMA/MMA can be conducted favorably,and this is a shortcut route to prepare triphase catalysts of PEG.It is found that Lewis catalysts are more effective than protonic acids for the ring-opening reaction of epoxy groups.The polarity of the solvents affects the coupling graft reaction between PEG and microspheres GMA/MMA greatly,and to use the solvents with higher polarity is advantageous to the graft reaction.In the graft reaction system,the additional crosslinking will be produced between the micromolecules on microspheres GMA/MMA if the used amount of the catalyst is excessive,and the additional crosslinking is adverse to the coupling graft of PEG.Under the suitable conditions,the PEG graft degree of the grafted microspheres PEG-GMA/MMA can get up to 0.20 g/g.
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发布时间：2021-03-19 - 摘要：The influence of thermal aging on dispersion stability and mechanical stability of styrene butadiene latex(SBL) was studied.It was found that with increasing the aging temperature,the SBL particles are easy to coagulate together and to form a solid gel within a short time period.However,the gelation ratio determined by Maron test showed that the mechanical stability remarkably increased for the thermal aged samples.To clarify the mechanism of the abnormal phenomenon,FTIR,GPC,as well as stress-strain behavior of the thermal aged SBL system were investigated.It is found that the reduction of dispersion stability is mainly due to lowering the barrier energy between the latex particles,and thermal degradation of poly(styrene-butadiene) in the colloid state is not oxidized into carbonyl group at the double-bond site,but turns into cross-linking between the macromolecules,resulting in an increase of mechanical strength of the SBL film.Correlation of the tensile modulus at 300% strain to the gelation ratio demonstrated that the improvement of the mechanical stability was originated from crosslink-induced high tensile modulus of the SBL particles.
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发布时间：2021-03-19 - 摘要：Porous poly(N-isopropylacrylamide)(PNIPAAm) hydrogels were prepared using sodium alginate(SA) as pore-making agent in aqueous NaCl solutions.The porous structure of the PNIPAAm hydrogels was confirmed by SEM and SAXS,and the results showed that the pores in the hydrogels were interconnected and their pore sizes were increased with the NaCl concentrations used in the polymerization media.Accordingly,the deswelling rates of the porous hydrogels were enhanced with the NaCl concentrations.The water retention ratio of the porous PNIPAAm hydrogel prepared in 0.6 mol/L NaCl aqueous solution was less than 15% within 1 min when the equilibrium-swollen hydrogels at room temperature was transferred into the aqueous medium at 45℃,and the deswelling equilibrium was achieved within 4 min.The porous structure of the PNIPAAm hydrogels may be caused by the micoparticles formed by coil-to-globule transition of sodium alginate chains in the NaCl solution.
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发布时间：2021-03-19 -
pH/TEMPERATURE DUAL STIMULI RESPONSIVE MICROGELS BASED ON INTERPENETRATING POLYMER NETWORK STRUCTURE
摘要：The microgels with in terpenetrating polymer network(IPN) structure based on poly(N-isopropyl acrylami de)(PNIPAM) and poly(acrylic acid)(PAA) were synthesized by seed-emulsion poly merization,using redox initiator at room temperature and the less crosslinked P NIPAM microgels as seeds.The microgels were determined to be composed of PNIPAM and PAA by Fourier transform infrared spectrometer (FTIR),and the IPN structur e in the microgels was confirmed by transmission electron microscopy(TEM).The results obtained by dynamic laser light scattering(DLLS) showed that the microg els had good pH/temperature dual stimuli responsiveness without any marked inter action.In the case of the pH of the aqueous media 5.5,the PAA component in t h e microgels had no effect on their volume phase transition temperature,but when the pH of the aqueous media was 4.0,their volume phase transition temperature was slightly decreased due to the formation of hydrogen bonds between PNIPAM and PAA.The pH stimuli responsiveness of the microgels was enhanced by the PAA co ntent within the microgels.- 24
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发布时间：2021-03-19 - 摘要：Poly[2-(2-chloroethoxy)ethoxy)x(trifloroethoxy)2-x] phosphaz ene (PCTFP) was synthesized with thermal ring-opening polymerization and then dual nucleophilic substitution method from hexachlorocyclotriphosphazene (HCCP) that purified by recrystallization twice an d sublimation once.The mole ratios of two substituents,which were 2-(2-chloroethoxy)ethoxy sodium and trifloroethoxy sodium,were 1∶3,1∶5 a nd 1∶65 respectivel y.The final substituted polyphosphazene products were purified through acetone-benzene precipitation to remove impurity.31P-NMR was used to as su re the purification.1H-NMR,FT-IR,GPC,DSC,XRD were used to characterize th ese PCTFPs,and gas permeability coefficient of different gases of these polymers were measured by the permeate gas pressure method.The results showed that trifl oroet hoxy and 2-(2-chloroethoxy)ethoxy had been grafted to the side-chain of polyp ho sphazene,and the x-value of these three different (PCTFPs) were 0.19,0.18 and 0.08 respectively.The glass transition temperature of these polymers were -7.37℃，-12.85℃ and -25 .68 ℃,and the weight-average molecular weight were 5.4×105，7.8×105 and 1.5 ×105 res pectively.Compared with 2-(2-chloroethoxy)ethoxy,trifloroethoxy group showed m ore competitive substitution under same reaction condition.The degree of crysta llinity of these three PCTFPs were lower than that of poly(bis-trifloroethoxy)phosphazene.In this paper th e degree of crystallinity of poly［(2-(2-chloroethoxy)ethoxy)0.18(trifloroethoxy)1.82］phosphazene decreased to 10.1% due to its appropriate ratio of the two s ub stituent groups.This polymer showed higher permeability.Its permeability coeff icients of CO2 and He were 88.9 barrer and 60.6 barrer respectively,and the se le ctivity coefficients of CO2/CH4 and He/CH4 were 24.1 and 16.4,which showed great potentiality to be applied in natural gas industry.In addition,this polymer pre sen ted special selectivity of H2/N2,which was about 0.2,and the permeation coef ficient of N2 was 8.5 barrer.It also showed special potentiality in ammonia sy nthesis industry.
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发布时间：2021-03-19 - 摘要：Catalytic chain transfer polymerization(CCTP) of methyl methacrylate(MMA) and γ-methacryloxypropyltrimethoxysilane (MPS) was perf orm ed using toluene as the solvent at 60℃ in the present of bis(boron difluorodim ethylglyoximate) cobaltate(Ⅱ)(CoBF) as catalytic chain transfer agent and AIBN as the initiator.Vinyl-terminated copolymers with low molecular weight were su ccessfully prepared by CCTP in this case. 1H-NMR was employed to prove the prese nce of vinyl unsaturated end groups of the as-prepared polymer.The effect of st ructure on thermal behavior was investigated by using thermogravimetry (TG) in n itrogen atmosphere.In contrast to PMMA-co-PMPS prepared in absence of CoBF ,the differential thermogravimetry (DTG) curves of the copolymer synthesized by CCTP show that only one sharp peak appears at 283℃,which presents the degradation r e sulting from the random scission of the backbone and the terminal double bonds.G PC was carried out to analyze molecular weight information of copolymers synthes ized in different conditions.Results illuminated that average molecular weight decreased with the increase of CoBF.Apparent chain transfer constants (Ct) were determined with the conventional Mayo procedure based on number(Mn) and w eigh t(Mw) average molecular weights,and with chain length distribution procedu re ba sed on peak(ΛP) and high(ΛH) molecular weight slopes.It could be f ound that the apparent chain transfer constants determined fromMw and ΛP we re similar and much better than others.In addition,on the basis of different monomer feed compositions,we found that Ct values were increased with the concentration of MPS.
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发布时间：2021-03-19 - 摘要：The polyethylene/carbon nanotube shish-kebab structures were prepared by both isothermally and non-isothermally solution crystallization method,and the disp e rsion of carbon nanotube in xylene was improved.From the TEM images,it is evid ent that lengths of kebabs were 30～140 nm and 40～180 nm,respectively.And the p eriodicities were both in the range 35～80 nm.The polyethylene/carbon nanotube s hish-kebab structures were well dispersed in the p-xylene solutions after 3 months.And based on the samples obtained during the process,it was obviously t hat t he kebab grew and formed simultaneously.Finally,to investigate the stability o f shish-kebab structures,it was washed by boiled xylene for several times.Alth ough,PE chains were dissolved in the process,shish-kebab structures would ref orm when temperature decreased.
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发布时间：2021-03-19 - 摘要：Silica-coated fluorescent nanoparticles functionalized with amine-or ester-po ly(amido-amide)(PAMAM) were synthesized and characterized by TEM,FTIR，TGA and z eta potential measurements.The efficiency of cellular uptake of nanoparticles，the cytotoxicity of nanoparticles toward 9L cell,and the distribution of nanoparticles in 9L cell were investiga ted by transmission electron microscopy (TEM),confocal laser scanning microscop y (CLSM),CCK-8 assay and flow cytometry analysis.TEM revealed the average siz e of nanoparticles was about 60 nm and the zeta potential of nanoparticles modif i ed with amine groups was +19.08,with ester groups was negative-9.01 at physio log ical pH ,respectively.FTIR and TGA results also testified that the two kind of s ilic a-coated fluorescent nanoparticles were respectively functionalized by amine- an d ester- PAMAM. CLSM demonstrated that most nanoparticles were distributed in cyt oplasm and were entrapped in endosomes.CCK-8 analysis showed that both nanopart icles had no apparent toxicity.Flow cytometry analysis indicated that the cellu lar uptake of nanoparticles by 9L cells was a concentration- and time- depende nt endocytic process,and the uptake of amine functionalized nanoparticles was mor e efficient than that of ester functionalized nanoparticles.
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发布时间：2021-03-19 - 摘要：Porous polyacrylamide (PAM) hydrogels with tuned po re size were prepared by frontal polymerization(FP) combined with foaming proces s.S tudies were conducted to investigate the effect of initiator concentration and r eactant diluents on the most relevant parameters of FP and the performances of t he final products.A dilution of the reactants resulted in an obvious decrease o f the front velocity as well as the maximum temperature of front.The pore diameters and the wall thicknesses showed an uptrend when the water content increased,and the swelling pr operties of the final products reduced.A significant enhancement of the propagation velocity was noticed with increasing of initiator concentration.The size of pore and swelling degree were characterized by a constant increase when APS c oncentration increased,and then,a large decrease was noticed.At an initiator/mo nomer mass ratio of 0.022,the maximum pore volume was obtained.
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发布时间：2021-03-19
Research Article
- 摘要：A convenient method was developed to fabricated helical nano-fiber yar n in one step and with high efficiency.Poly(vinyl pyrrolidone) (PVP) sol (Mw =1.3×106，10% in ethanol) was electrospun at the voltage of 25 kV,using a t hin upright copper needle as a collector with the rotation speed of 0～1200 r/min.In t hi s setup,centimeters-long precursor fibers are spontaneously electrospun on the tip of the upright needle target parallel to the electric field.The electrospin ning process is mainly controlled by the electrostatic forces.Thus,when a grou nded needle is close to the splaying jet,the splaying jet will be converged and then deposed on the needle.The yarn was formed between the needle and the spin neret,and the jet will be folded and aligned to form a self-bundling yarn.The morphologies of helical fiber were observed by scanning electron microscopy (SEM ).The morphologies of PVP fibers were changed from non-helical,dispersed-helic al to tight-helical fibers forming a multi-filament yarn in the various ro t ating speeds.The Coulomb attracting force (in the vertical direction due to the static fields between the jet and the copper thread),the Coulomb excluding forc e between the spinning fibers (in the horizontal direction) and the shear force (in the tangential direction due to the high rotation speed by copper needle) ar e the three main factors to form the helical fibers.The main advantages of prod ucing PVP fiber yarns by this technique are the minimum polymer degradation and forming the multi-filament yarns having a high tenacity.
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发布时间：2021-03-19 - 摘要：Polyoxymethylene (POM)/multi-walled carbon nanotubes (MWCNT) composites were pr ep ared by melt mixing MWCNTs and POM in a rotational rheometer.The morphology,con ductive property,dynamic rheological property,thermal property and crystallizati on behavior of the composites were investigated.It was found that MWCNTs,without any modification,dispersed homogeneously in the POM matrix.The conductive perco lation effect was observed when the MWCNTs content was 1 wt%,with the percolatio n threshold between 0.5 wt%～1.0 wt%.The thermal conductivity of POM/MWCNT com posites increased to 0.5289 W/(K m) with the addition of 1.0 wt% MWCNTs ,1.5 times higher than that of pure POM [0.198 W/(K m)].When the content of MWCNTs is further increased,the thermal conductivity of the composites hardly cha nged.The effective media approach (EMA) was used to confirm that the moderate i ncrease of thermal conductivity was contributed to the interfacial resistance be tween MWCNTs and POM.MWCNTs have significant nucleating effect on POM,and 0.5 wt% MWCNTs could enhance the crystallization temperature of POM by about 6℃,b ut did not improve further with additional addition of MWCNTs.The complex viscos ity,storage modulus and loss modulus of the composites increase with the conten t of MWCNTs.
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发布时间：2021-03-19 - 摘要：By one-pot technique the copolymerization of styrene with ethylene promoted by a cyclopentadienyl titanium trichloride (CpTiCl3)/1,4-butanediol di glyci dyl ether (BDGE)/Zn catalytic system to yield aPs-b-P(S-co-E)- b-PE block copolym ers was investigatedvia sequential monomer addition strategy in the presenc e of methylaluminoxane (MAO) as cocatalyst for the coordination polymerization stage. The effect of temperature,time,ethylene pressure and the ratio of Al/Ti in mol on the polymerization performance was discussed in detail.Basically, aPs-b-P(S-co-E)-b-PE block copolymers was obtained,togethe r with atactic polyst yrene through the approach,which was determined by solvent extraction.The CHCl3-soluble product was determined by GPC,DSC,WAXD and 13C-NMR.The molecular weig ht distribution (MWD) of the copolymer varied slightly at the range from 1.71 t o 2.11The DSC result showed that the copolymer featured one glass transition te mperature (for example Tg= 86℃) attributed to the Tg of aPs domains an d one melting point (for example Tm= 114℃) attributed to the Tm of PE domains.The blocky microstructure of the copolymer was further confi rmed by WAXD and 13C-NMR.These results indicated that the copolymer was consisted of amorphous aPs segments,P(S-co-E) segments and crystalline PE segmen ts.
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发布时间：2021-03-19 - 摘要：A new method was developed for preparation of phenolic hollow microspheres via in situ polymerization.Tetraethyl orthosilicate being the core and poly(acrylic acid) being the anionic surfactant were placed into flask,the mixture was stirred, and its pH value was adjusted to be acidic,then a s table oil-in-wa ter emulsion was formed.Tetraethyl orthosilicate was emulsified uniformly in the aqueous solution and dispersed into a large quantity of droplets with very smal l size covered by anionic surfactant of poly(acrylic acid).The pre-prepared res oles,being the shell,were dribbled into the flask slowly.The mixture was stir red at 60℃and hold for 3 h,and at 90℃ hold for 2 h,respectively.A large numb er of yellow microspheres were formed.The “core-shell" phenolic microspheres w e re then filtered and dried.Hollow phenolic microspheres were produced after the yellow solids dried at 170℃ for 4 h to eliminate tetraethyl orthosilicate from the microspheres in an oven.The hollow phenolic microspheres were characterized by scanning electron microscopy (SEM),Fourier-transform infrared spectroscopy( FTIR) and th ermogravimetric analysis (TG).FTIR indicates that a significant number of the hy dr oxymethyl groups remain in the microspheres,which provide adherence force with t he matrix resin during application.TG analysis demonstrates that the resultant holl ow phenolic microspheres have good thermal stability.SEM results show that the average of diameter of the microspheres is about 600 μm.The hollow microspheres have good close cell and smaller pores formed in the wall when water vaporized ,It is also observed that the morphology of microspheres is very tough,which ca n provide good bonding between microspheres and resin matrix.
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发布时间：2021-03-19 - 摘要：A novel amphiphilic copolymer having polysulfone (PSF) backbone and poly［poly(e thylene glycol) methyl ether methacrylate］ side chains［PSF-g-P(PEGMA)］ was synthesized by ATRP,using chloromethylated polysulfone as macroinitiator.The resultant copolymer was characterized by FT-IR and 1H-NMR.The molecu lar weight of PSF-g-P(PEGMA) was calculated as 6.34×104 based on 1H-NMR analysis, the molar fraction and weight fraction of P(PEGMA) in the co polymer was 0.711 and 39.6 wt%,respectively.A series of PSF blend membranes co ntaining various amounts of PSF-g-P(PEGMA) were prepared by the wet phase inversion process and were characterized by SEM,XPS,water contact angle and bovi n serum albumin (BSA) adsorption.The experimental results showed that the introd uction of PSF-g-P(PEGMA) can significantly improve the hydrophilicity and fouling-resistance of PSF membranes.For instance,the initial water contact angl e of the PSF membrane containing 20 wt% PSF-g-P(PEGMA) was 43.5°.After 50 s,the blend membrane was completely wetted by water.The apparent BSA adsorptio n amount of the same membrane was extremely low compared to that of the pure PSF membrane.
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发布时间：2021-03-19 - 摘要：Thin-film composite nanofiltration membranes were prepared by a simple dipping and crosslinking process.A polysulfone (PSF) ultrafiltration membrane was used a s the support and a crosslinked hyperbranched polyester (HPE) as the active sepa ration layer.The separation layer was immobilized onto the support via the aldol condensation of HPE with glutaraldehyde (GA).The prepared membranes were charac terized by attenuated total reflection Fourier transform infrared spectroscopy ( ATR-FTIR),water contact angle measurements and scanning electron microscopy (SE M).The results of FTIR examination confirmed the existence of crosslinked HPE la yer on membrane surface.The results of SEM observation indicated that a thin den se layer of crosslinked HPE was deposited on the support membrane.Water contact angle measurements showed that the membrane hydrophilicity was significantly imp roved.The effects of HPE concentration and GA concentration during membrane prep aration on the separation and permeation properties were investigated.The optimi zed HPE and GA concentrations were 9.8 g/L and 7.4 g/L,respectively,and t he water flux for the resultant membrane reached 69.6 L/(m2#12539;h),and the Na2 SO4 rejection ratio was 93.2%.The sequence of rejection ratio to various sal ts was Na2SO4＞NaCl＞MgSO4＞MgCl2,which was characteristic of electron egative nanofiltration membranes.These results showed that a high performance na nofiltration membrane with low operation pressure,high permeability and high rejection could be obtained by the present process.
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发布时间：2021-03-19 - 摘要：A novel reaction route to prepare the derivate of chitosan with β-CD immob ilized at C6 position is proposed. It is reliable and of high efficiency.The a mi no group of the chitosan was protected by reacting with the benzaldehyde,and th e schiff base stucture was generated.The hydroxyl group in the schiff base chito san was tosylated by reacting with p-toluenesulfonyl chloride.Then the mono amino substituted β-cyclodextrin was immobilized onto C6 position of ch itosan by a nucleophilic displacement reaction between the tosylated chitosan an d the amino in cyclodextrin derivate.Finally,the schiff base structure was depro tected in the acetic acid solution,and β-CD immobilization derivate of ch itosan on C6-OH (CTS-CD) was prepared.The chemical structure of each resulta nts was analyzed by FTIR, 13C-NMR, elemental analysis and UV,respecti vely.The UV absorption peak around 490 nm could be observed for the concentr ated sulfuric acid hydrolysis products of CTS-CD.However,the corresponding hydrolysi s products of CTS did not show any absorption peak near this range.By drawing th e calibration curve of the concentrated sulfuric acid hydrolysis products of β-CD through the UV spectrum,the immobilization amount of β-CD on the C6 position of chitosan could be quantitative detected.The obtained immobiliza ti on amount was 170.81 μmol.g-1,which was by head and shoulders high tha n the c orresponding values reported in literature.The crystallization properties of each resultants were studied through XRD characterization.
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发布时间：2021-03-19
Research Bulletin
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