最新刊期
卷 ， 期 3 ， 2002
- 摘要：Relations between mechanical properties and conformational contents of native silkworm silk are investigated．Three species of silkworm cocoons,bombyx mori,tussah and eri-silkworm,are chosen and the three corresponding degummed silks are obtained by a strong alkaline solution and a relative neutral solution,respectively．For the six kinds of silk fibers,the load-elongation curves and the infrared spetra of protein are measured．To transfer load into stress,the section area of silk is directly measured by SEM observation．The contents of four conformations,α-helix,β-sheet,β-turn and random coil,can be calculated by the infrared spectra．Infrared analysis shows that the β-sheet andα-helix structures may be destroyed by the strong alkaline solution during the degumming and the destroyed molecular chains transform into random coils. So the strength and elastic modulus of bombyx mori and tussah silks are reduced drastically after degumming．In contrast,there is no significant change in the mechanical properties and the conformational content of protein for the degummed eri-silkworm silk treated by relative neutral solution．The experimental results show that fractions of β-sheet and α-helix structures,especially β-sheet,contribute to the strength and rigidity of silkworm silk．There is a good correlation between β-sheet content and mechanical properties．But the correlation is not very significant for α-helix because its content is very low．The infrared analysis also shows that the contents of β-turn structures for all silks retain invariant,which indicates that β-turn structure indeed exists in native silkworm silk and its contents seem not to be influenced by the species and the degumming．
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发布时间：2021-03-19
Rapid Communications
- 摘要：Research on the novel hybrid polymerization system of hexamethoxymethyl melamine (HMMM)-polyol-acrylate-acid has been reviewed. The hybrid system involves a condensation reaction of HMMM and free radical polymerization of acrylate,although there is no free radical initiator in the compositions．It is suggested that active methylene groups can be oxidized to the corresponding hydroperoxide through a charge transfer complex (CTC) between HMMM and O2 in the air．Catalyzed by acid,the hydroperoxide decomposes rapidly,generates free radicals and then initiates the free radical polymerization．There are some synergetic effects between the radical polymerization and condensation reaction．First,the curing rate could be enhanced greatly．Secondly,DSC trace of the hybrid polymerization system demonstrates that there is obvious energy compensation effect in the system．The released energy of the free radical polymerization of acrylate can be transferred to the endothermic condensation reaction of HMMM．Thirdly,the properties of cured film,such as mechanical properties and solvent-resistance,are gready improved．It is demonstrated that the improvement is caused by the formation of polymer alloys with IPN (Interpenetrating polymer network) structure in-situ via dynamic mechanical thermal analysis (DMTA) and transmission electron microscope (TEM)．In addition,acrylate can adjust the viscosity of the formulation and reduce the use of volatile organic compound (VOC)．To make the formulation more flexible,some new compounds containing very active methylene groups and hydroxyl group such as diethylene glycol allyl ether and diethylene glycol benzyl ether were synthesized and used as the crosslinker-initiators in the hybrid polymerization system. To increase the shelf-time of the formulation,latent acid catalysts trans-2-hydroxycyclohexyl-p-toluenesulfonate and pyridine p-toluenesulfonate,were used as the source of acid in the hybrid formulations．The application of hyperbranched polymers in hybrid polymerization system is under study．Consequently,the hybrid polymerization system of HMMM-polyol-acrylate-acid is promising to formulate a high curing rate,low solvent content,energy conservation and high quality coating．
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发布时间：2021-03-19
Feature Articles
- 摘要：A double metal cyanide(DMC) complex based on Zn3[Co(CN)6]2 is prepared and it is characterized by IR,XRD,TGA．This catalytic system is highly active for the ring-opening polymerization (ROP) of propylene oxide,and gives polymers that have narrow MWD(＜1.40) and low unsaturation(＜0.014 meq／g)．The molecular weight of polymer is entirely controlled by reacted monomer to initiator molar ratio(M／I)．The polymers prepared with stepwise addition of monomer exhibit narrower MWD compared with those prepared by one-step addition of monomer．The polymerization involves a rapid exchange equilibrium between the active species and inactive chains． It has also been proved that chain termination of this catalytic system is reversible or temporary．The active centre of catalyst is electron-accepting．The microstructure of the polymer is determined with 13C-NMR spectroscopy．The polymer has a random distribution of the configurational sequences and head-to-hail regiosequence．It is assumed that the polymerization proceeds via a cationic coordination mechanism．
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发布时间：2021-03-19 - 摘要：In recent years,magnetic microspheres have been widely used in cell separation,protein purification,immunoassays and as diagnastica and therapeutica．Further founcfionalized microsphere are attracting more attention．A slight blue magnetic polymer microsphere with photoconductivity was synthesized by dispersion copolymerization with styrene and reactive Fe-phthalocyanine in the presence of magnetic fluid．The microsphere has a core-shell structure,the core is Fe3O4 magnetic fluid,and the shell is a copolymer of styrene and reactive Fe-phthalocyanine．The content of magnetic fluid and Fe-phthalocyanine in the microsphere is 1.833％ and 1.43％ respectively．The average size of microsphere was 55.317 μm with multi-distribution range from 6～200 μm．The two important properties of the microsphere,magnetic responsiveness and photoconductivity,were investigated．It shows a good magnetic responsiveness in magnetic field and a good photoconductive property at 762.5 nm．
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发布时间：2021-03-19 - 摘要：The Glycidyl Methacrylate(GMA)／Styrene(St) multi-monomer melt-grafted polypropylene,PP-g-(GMA-co-St),which has a high grafting degree of GMA,was blended with Polyamide 6 (PA6)．The morphologies and crystallization of the blends were investigated by means of SEM,DSC and WAXD．PP-g-PA6,which formed during the reactive blending process,improved greatly the compatibility of the blends and reduced the size of the dispersed phase dramatically．In the PP-g-(GMA-co-St)／PA6=3／7 blend,the fractionated crystallization of PP-g-(GMA-co-St) was observed．The crystallization of PP-g-(GMA-co-St) at the lower temperature should be assigned to homogeneous nucleation. In the 7／3 blend,due to the fine dispersion of PA6 phase,PA6 did not crystallize at its normal crystallization temperature (Tc),but crystallized in the mode of homogeneous nucleation at a lower Tc simultaneously with the crystallization of PP-g-(GMA-co-St)．The WAXD showed PP-g-(GMA-co-St) and PA6 crystallized separately and no new crystalline forms formed in the blends．
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发布时间：2021-03-19 - 摘要：Hydrogels based on n-alkyl methacrylate esters(n-AMA),acrylic acid and acrylamide cross-linked with 4,4′-di(methacryloylmino)azobenzene were preparared,and their deswelling kinetics was studied．The hydrogels swellon at pH values of 7.4 and 8.0 were transferred into buffered solutions at pH2.2 and pH4.0 respectively．The processes of deswelling appear in both cases：The first is that hydrogels deswelled immediately after the immersion of the swollen hydrogels into the lower pH of buffered solutions；the other is that hydrogels proceeded a short time swelling before deswelling．For the former the reciprocal of the average rate of deswelling [t/(Ht-H0)] has an excellent linear correlation with the time of deswelling．For latter the reciprocal of square root of water uptake in unit time [(t／Ht)1/2] has an excellent linear correlation with the time of deswelling．
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发布时间：2021-03-19 - 摘要：A new late metal-transition complex {[(2-ArN=C(Me))2—C5H3N]FeCl2}(Ar=2,4-C6H4(CH3)2) was designed and synthesized．The behavior of ethylene oligomerization catalyzed by this complex with MAO as cocatalyst has been studied．The effects of temperature,Al／Fe molar ratio,the concentration of catalyst and ethylene pressure on the catalytic activity and the rate of oligomerization were investigated．It was found that the catalyst is characterized by its high activity (the maximum is up to 4.25×108 g oligomer/molFe·h at 30℃,and 3.0 MPa) and high initial reaction rate．The kinetic curves obtained is of decay type．
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发布时间：2021-03-19 - 摘要：Curing behaviors and kinetic analysis of novel poly (phenothioxine-formaldehyde) (POSPF)resin were studied by means of IR,DSC and TG．It was shown that active hydroxymethyl groups changed into methylene in the curing process of resin by the use of hexamethylene-tetramine／α,α′-dichloro-m-xylene as curing agents. The exothermic peak on the DSC curve is wide and smooth because of lower activity of curing reaction．Initial temperature (Ti=100℃),curing temperature(Tp=18l.5℃)and terminal temperature(Tf=225.7℃) were calculated by extrdpolating T-β．The cured resin has good heat-resistance．The temperature of 5％ thermal weight loss reach up to 403℃.
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发布时间：2021-03-19 - 摘要：According to the mechanism of hydrosilylation,the process of“normal-sequence-dripping mode” was designed．And using such process,the monomers of dichloromethylphenethylsilane and dichloromethyl (n) hexylsilane were synthesized with high productivity(the maximal productivity of dichloromethylphenethylsilane,88％,and dichloromethyl-n-hexylsilane,96.2％) and low pollution (minute quantity of fumes in off-gas)．By Wurtz reductive coupling reaction of dichlorosilane(dichloromethylphenethylsilane and dichloromethyl(n)hexylsilane)and trichlorosilane (trichloromethylsilane and trichlorophenylsilane),four series of two-dimensionally branched copolysilanes were designed and synthesized using the two procedures of “pre-polymerization” and “mixed-polymerization” with or without diglyme. The polymers are polymethylphenethylsilene-co-methylsilynes,polymethyl-phenethylsilene-co-phenylsilynes,polymethyl-n-hexylsilene-co-methylsilynes,and polymethyl-n-hexylsilene-co-phenylsilynes．Through the characterization of GPC,UV,1H-NMR and 29Si-NMR,the properties of such copolysilanes were determined．The effects of such factors as monomer characteristics,co-polymerization ratio (D／T),co-polymerization mode(“pre-polymerization” and“mixed-polymerization”),solvent additive(diglyme)and reaction time on the polymer properties,such as productivity,molecular weight and UV absorption spectra,were studied and discussed．It was discovered that the branched copolysilanes of very high molecular weight with highly bulky substituents could be obtained with “pre-polymerization”．The maximum of the molecular weight of such branched copolysilanes could reach 2.8×105,which was at least ten times as those of the branched copolysilanes derived from the mixed-polymerization procedure．The mechanism of increasing the molecular weights of branched copolysilanes was proposed
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发布时间：2021-03-19 - 摘要：Composite microemulsion of anionic polyurethane acrylate polymerizable emulsifier (APUA) and MMA was polymerized with AIBN and K2S2O8 as initiator respectively,and the nanometer core-shell latex particle was synthesized．In the latex particles polyurethane is as the shell of the latex particles and PMMA as the core．Effects of APUA content and polymerization temperature on polymerization kinetics were studied．Influences of different initiators and emulsifier concentration on morphology and size of latex particles were observed by TEM. The results suggest that stable core-shell P(MMA-UA) nanometer latex particle can be synthesized by polymerizable emulsifier APUA,and the particle size is about 50 nm；with increasing APUA emulsifier content,size of latex particles decrease. Effects of different kind of initiators on properties of latex were significant．When APUA was used as emulsifier and K2S2O8 as initiator,hydrogel of P(MMA-UA)may appear during polymerization or storing．
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发布时间：2021-03-19 - 摘要：Monodispersity is one of the important characteristics of magnetic polymer microspheres．In this paper,monodisperse magnetic poly(styrene／butyl acrylate／methacrylic acid) [P(St／BA／MAA)] microspheres with the size ranging from 80 to 230 nm,were prepared by emulsifier-free emulsion polymerization in the mixture of water and polar solvent,such as acetone,ethanol or methanol,in the presence of ferrofluid prepared by a co-precipitation method．The effects of the medium polarity and the surfactant content in ferrofluid on the particle size and monodispersity of magnetic P(St／BA／MAA) microspheres were discussed in detail．The results showed that the electrostatic repulsion between microspheres and radicals had a geat effect on the monodispersity of magnetic micropsheres．Proper repulsion benefited the monodispersity,but the higher or lower repulsion would lead to the decrease in monodispersity．Moreover,the results revealed that some features of emulsifier-free emulsion polymerization in the presence of ferrofluid was analogous to that of conventional emulsifier-free emulsion polymerization．
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发布时间：2021-03-19 - 摘要：Isocyanurate made from HDI by using potassium acetate as catalyst was synthesized and characterized by IR and NMR(1H,13C,1H-1H COSY,13C-1H HMQC,13C-1H HMBC)．The peaks atδ3.29～3.32,δ3.86,δ3.27,δ3.70,δ4.45,δ3.25 and δ3.45 of the 1H-NMR spectrum were attributed to the hydrogen proton on the α carbon atom connected with the nitrogen atom of N=C=O,the hydrogen proton on the α carbon of the HDI trimer,the hydrogen proton on the carbon connected with the nitrogen of urethane,the hydrogen proton on the α carbon of biurea,the hydrogen proton on the carbon connected with the oxygen atom of the carbonyl group of ureido-formate,the hydrogen proton connected with biurea,the hydrogen proton connected with substituted urea,the hydrogen proton connected with the urea carbonyl group of ureido-formate,respectively．The peaks at δ121.46,δ148.58,δ153.60,δ153.91,δ154.36,δ155.44,δ155.93,δ165.29 of the 13C-NMR spectra belonged to the double bonded carbon of N=C=O,the carbon on the carbonyl group of the HDI trimer,the carbon on carbonyl of urethane,carbon on the carbonyl of dual-biurea,the carbonyl of the ureido-formate,the carbon of the carbonyl of biurea,the carbon on the carbonyl of substituted urea．and the carbon on the carbonyl of ureido-formate．The results showed that the main product of HDI self-polymerization was its trimer,isocyanurate．Isocyanurate and isocyanate groups were the main groups in the trimer．Urethane,urethaneurea,urea,biurea groups were also detected in little amount．1D and 2D NMR could differentiate seven sorts of carbonyl groups and one N=C=O group,and establish the connections of all carbon and hydrogen atoms of mixed structures that originated from eight different substitutions．The content of NCO groups was derived from the results of the NMR characterization,it was about 21％．By using the statistical method,the average molecular weight and functionality of the trimerization product were calculated as well,they are 624～632 and 3.1～3.2,respectively．The consistence of the calculated values of isocyanate content,mean functionality and mean molecular weight with the experimental values(20％,3 and 618) demonstrated the correctness of structure characterization．
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发布时间：2021-03-19 - 摘要：Supported polyimide-titania hybrid membranes were prepared by sol-gel technique and characterized by the methods of ESEM,IR,TG-DTA,mercury porosimetry and gas permeability measuring apparatus to get their surface morphology,structure,thermal performance,pore size distribution and gas permeability properties．The results showed that new type structure of organic phase containing inorganic phase between polyimide and titania particle by bond conjunct was formed．The discomposing temperature was decreased with the increasing of TiO2 contents,and the thermal stability was better than polyimide materials under the temperature of 450℃．The pore size increased with the increasing of TiO2 contents,and pore size distribution tended to disperse．The permeability of N2,H2 and CO2 across the membrane were controlled by Knudsen diffusion,and the memebrane exhibited outstanding hydrophilicity since their permeation coefficients of H2O／N,are higher than the Knudsen diffusion values．
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发布时间：2021-03-19 - 摘要：Maleic anhydride grafted polypropylene (gPP)／expanded graphite (EG) electrically conductive nanocomposites were prepared via solution intercalation (SI) method．In contrast to melt mixing (MM) method,the relationships between preparation method,microscopic structure and conductivity of gPP／EG composites were investigated by means of measurement of electrical conductivity (σ) and OM,SEM and TEM observatians．The results show that the percolation threshold at room temperature (φc) of the nanocomposites prepared via SI method is 0.67 vol％,which is much lower than that of the composites prepared via MM method (φc=2.96 vol％)．At EG content of 3.90 vol％．the σ of the former attains 2.49×10-3 S／cm,but that of the latter is only 6.85×10-9 S／cm．The reason causing the differences mentioned above is direcdy related to the morphology and the internal microstructure of EG dispersed phase in the composites prepared via two methods．
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发布时间：2021-03-19 - 摘要：A novel polyurethane containing main-chain electron donating-accepting azobenzene chromophores has been prepared. Compound (Ⅰ) 4-carboxyl-4′[(2-hydroxyethyl)-ethylamino]-azobenzene was synthesized from azo coupling reaction between p-aminobenzoic acid and N-ethyl-N-hydroxyethylaniline．Monomer (Ⅱ) 4-[(2-hydroxyethyl)ethylamino]-4′-(2-hydroxyethyloxycarbonyl) azobenzene was obtained by reaction between (Ⅰ) and 2-chloroethanol．The chemical structure and purity of the compound (Ⅰ) and monomer (Ⅱ) were confirmed by the characterization of 1H-NMR,FTIR and UV-Vis spectrometry．Through the polymerization reaction between azo monomer(Ⅱ) and TDI,the azo polymer was obtained．The chemical structure of polymer was characterized by 1H-NMR、FTIR and UV-Vis spectrometry．The molecular weight and its distribution were determined by GPC to be Mn=4800 with a polydispersion index 1.3．From DSC thermogram,a glass transition temperature of 119℃ was observed．The polymer synthesized exhibits significant photodynamic behavior. Surface profile gratings were optically inscribed upon exposure to an interference pattern of Ar+ laser beam at modest intensities．The surface modulation was about 220 nm and the first order of diffraction efficiency was up to 24％.
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发布时间：2021-03-19 - 摘要：The size,monodispersity and surface properties of polymer microspheres are especially important in biomedical field,information industry and microelectronics applications. The aim of the study is to obtain monodisperse microspheres carrying functional group in the micron size range by copolymerization．In this study,monodisperse St-MMA copolymer microspheres with a diameter of 5.4 μm were prepared by dispersion polymerization in absolute ethanol media using polyvinylpyrrolidone K-30(PVP) as a steric stabilizer and 2,2′-azobisizobutyronitrile (AIBN) as an initiator．The comparison of dispersion polymerization and emulsion polymerization indicated that their reaction mechanism were different．The copolymer microspheres prepared by emulsion polymerization were in the size range of 0.1～0.5 μm and the size distribution was broad．The kind of copolymer microspheres can coagulate easily and disperse hardly because of the residual emulsifer. The copolymer microspheres prepared by dispersion polymerization were spherical,monodisperse and were able to disperse easily．The statistical results showed that the size distribution of copolymer microspheres conform to normal distribution．The average size was 5.4 μm．The standard deviation(δ) was 0.16 and the dispersion parameter (ε) was 0.02．The SEM photographs showed that the copolymer microspheres had smooth surface and good sphericity．The FTIR results showed that the functional group (MMA) had been successfully incorporated onto the microspheres by copolymerization．
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发布时间：2021-03-19 - 摘要：The rheological characteristics γ-poly(glutamic acid) (γ-PGA) solution have been investigated. The solution is a typical non-Newtonian shear-thinning fluid with a characteristic n-parameter lower than l．With temperature raised,the viscosity of γ-PGA solution shows the trend of decreasing．Over the angular frequency(ω) range 0.01～100 rad·s-1,the storage modulus (G′) of 5％ (W/V) γ-PGA gels is much higher than its loss modulus (G″) and loss dependent on frequency which showed that γ-PGA has fine elasticity．1％ is close to the threshold concentration needed for gelation．γ-PGA is dispersible in cold water to form weak gel．Continuous heating at high temperature treatment changed the network of γ-PGA gel．Similar results are observed for γ-PGA gels prepared under pH 4 and 12．Addition of 1％～10％ NaCl,7％KCl,MgSO4,ZnSO4 and CaCl2 decrease the G′ of 2％ γ-PGA gel at low frequency and increased G″ over the frequency rang 0.01～100 rad·s-1 which indicated that the formation of elastic network is hindered. However,addition of 1.7％ PbNO3 of 1.7％ AgNO3 makes total loss of viscoelasticity of the 2％ γ-PGA system．
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发布时间：2021-03-19 - 摘要：The benzylated wood dissolved in tetrahydrofuran,the solution may be used as polyols to prepared the thermoset materials．Hydroxyl number of the lower solution of liquefied benzylated wood was studied to determine the effect of the liquefaction conditions on the degree of liquefaction of benzylated wood,and the upper solution of liquefied benzylated wood was studied with GC-MS. It is proved that it was the dense products in the lower solution of liquefied benzylated wood that can be used as polyols．In order to maintain the strength of the thermoset materials made from benzylated wood,the liquefaction time and the liquid ratio should be no more than 6 h and 6:1,respectively,and it was also elucidated that the mixture of HCl and H3PO4 is better than HCl or H3PO4 alone．
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发布时间：2021-03-19 - 摘要：Fast responsive thermosensitive PNIPA hydrogels were synthesized by using different meshes of CaCO3 particles as pore-foaming agent．From the observation by a scanning electron microscope,it was found that these gels consisted of a porous structure．The gels possess pores in the size range 10～100μm．Such porous hydrogels swelled or shrank much faster in response to the change of temperature than conventional hydrogels．More than 90％ of water could be expelled from the porous hydrogels within 10 min when the temperature of the hydrogels was raised to 40℃. The reswelling curve of the xeogel was compared with the reswelling curve of the hydrogel shrunk to equilibrium state at 40℃,which showed a significant difference and an inflexion was found in the former．In comparing with the shrinking-rate,the swelling-rate of the porous hydrogels is relatively slower．
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发布时间：2021-03-19 - 摘要：Thermodynamic behavior and water state in the hydrogels were investigated for the fast responsive thermosensitive poly(N-isopropylacrylamide) hydrogels which were prepared by adding CaCO3 as a pore-foaming agent during the polymerization．The results indicated that the swelling ratio increased as the content of CaCO3 in the reactants increased．The effect of crosslinking agent on the swelling ratio showed that the more the crosslinking agent content,the lower the swelling ratio．The gel phase transition temperature was not influenced by the content of CaCO3 and crosslinking agent,but it decreased linearly as the NaCl content in water solution increased．DSC was used to study the state of water in the porous hydrogels swollen in deionized water and different content of NaCl solution. Results showed that three states of water exist in all these porous hydrogels. The effect of the content of CaCO3 and ionic strength on the three states of water was also investigated．
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发布时间：2021-03-19 - 摘要：A molecular thermodynamic model for copolymer mixtures has been established by combining a reference term for hetero-nuclear hard-sphere chain fluids with Alder et al．’s square-well attractive potential served as a perturbation term．The segment parameters of polymer (including segment number,segment diameter and interaction energy between segments) can be obtained by fitting pVT data of pure homopolymer．The adjustable interaction parameters between segments of polymers can be determined from liquid-liquid equilibrium data．This model can be used to correlate coexistence curves for homopolymer/copolymer systems．The effect of copolymer composition on lower critical solution temperature (LCST) and phase separation temperatures are investigated and compared with experiment results for r1/(CXD1-X)r2 copolymer mixtures．For (AXB1-X)r1／(AYB1-Y)r2 copolymer mixtures,the interaction parameters between segments of polymers can be obtained from the boundary between miscible and immiscible regions．It was found that the model can satisfactorily be used to correlate phase behaviour including coexistence curves,miscibility windows and miscibility maps for (AXB1-X)r1／(CYB1-Y)r2 copolymer mixtures,only a pair of adjustable interaction parameters need to be determined from the boundary between miscible and immiscible regions.
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发布时间：2021-03-19 - 摘要：Fullerols were electrostatically self-assembled into composite thin films with the precursor of poly(p-phenylene vinylene)(PPV) and with poly(diallyldimethylammonium chloride)(PDDA)．The composite thin films were characterized by UV-Vis spectroscopy (UV-Vis),atomic force microscopy (AFM),transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy(XPS)．The UV-Vis data showed that there were linear increments in the optical absorption at given wavelengths of the composite thin films as the bilayer numbers of the thin films were increased and that the assembling processes were consistent and reproducible from bilayer to bilayer. AFM images showed that clusters of dozens to a hundred or so nanometers in diameter were formed after the fullerols were assembled onto the substrates．If the aqueous solutions of fullerols were filtered before thin film assembling,the composite thin films would be statistically uniform．Otherwise,crystalline C60 would be embedded into the thin films．XPS data confirmed that C60 was modified into fullerols and electrostatically assembled with the polycations．Fullerols can easily be assembled with PPV precursor and PPDA into composite thin films,the resulting thin films being tougher than many self-assembled polyelectrolyte thin films perhaps due to stronger electrostatic attractive interaction between the fullerols and the polycations.
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发布时间：2021-03-19 - 摘要：Potassium salt of dicyclopentadienoic acid DCPD(COOK)2 was used as crosslinking agent for chlorinated polyethylene(CPE) system which contained compounding ingredients．Through direct blending reaction method,crosslinked CPE with mechanical properties closed to the normal vulcanizate was obtained．The effect of reaction time,temperature,catalyst and the dosage of crosslinking agent on mechanical properties of crosslinked products were studied．Test results indicated that the crosslinkage was formed through esterification between the chlorine-carbon on CPE molecular chain and the carboxylic salt groups of crosslinking agent．The mechanical properties of the carbon black filled CPE crosslinked with DCPD(COOK)2 was very closed to the normal vulcanizate cured with sulfur-accelerator system．However,this crosslinked CPE could be reformed for three times indicating it has plasticity,and the mechanical properties such as tensile modulus,tensile strength and permanent deformation etc．of the reformed products could be improved with reform times．Based on above fact,a new type of CPE thermoplastic elastomer with thermally reversible covatent crosslinkage and better compositive physical properties has been obtained．
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发布时间：2021-03-19 - 摘要：The effect of diethylene glycol dimethacrylate graft treatment on the structural changes of the silk fibers was examined in relation to the graft yield on the basis of the results of scanning electron micrograph photographs (SEM),infrared spectroscopy(IR),birefringence(Δn),X-ray diffraction and amino acid analysis．The diethylene glycol dimethacrylate grafted silk fibers with different amounts of graft yield showed a substantial decrease of the amino acid composition of Tyr．,His．,Ser．,Arg．The other amino acid residues remained essentially unchanged or showed only slight changes,so,the diethylene glycol dimethacrylate exhibited reactivity toward Tyr．,His．,Ser．,and Arg．of silk fibers．X-ray diffraction patterns of silk fibers suggested that the diethylene glycol dimethacrylate grafting does not affect directly the crystalline regions,but causes a decrease of molecular orientation in the amorphous regions．Birefringence(Δn) of silk fibers decreased by grafting with the diethylene glycol dimethacrylate．When the graft yields ale more than 35％,the surface of silk fibers showed the presence of several granules,consisting of the diethylene glycol dimethacrylate polymers,and the cross-sectional area of silk fibers showed the appearance of separating fiber．The IR of the grafted silk fibers showed absorption bands at 1651 cm-1 (amide Ⅰ) and 1520 cm-1 (amide Ⅱ) assigned to the β structure of the silk fibroin and additional bands at 1732,1134 and 1041 cm-1,characteristic of the spectra of the diethylene glycol dimethacrylate polymer. Additionally,the IR of the grafted silk fibers showed overlapped absorption bands due to the molecular conformation of this fiber and the diethylene glycol dimethacrylate polymer,giving evidence that the the diethylene glycol dimethacrylate graft occurred inside the fiber matrix. Thus the theoretical basis is provided for the silk chemical finishes or modification.
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发布时间：2021-03-19
Research Article
- 摘要：The poly(styrene-co-maleic anhydride))(SMA) was modified by some fluorescent organic molecules such as 2-amino-benzimidazol,4-amino-antipyrine and 4-amino-N-(2,4-dimethylphenyl)-1,8-naphthalimide to prepare the fluorescent polymers (SMI)．The FT-IR spectra of these polymers show a new carbonyl characteristic peak in imide ring appeared at 1722 cm-1 and no amino group characteristic peaks appeared at 3300～3500 cm-1.That is to say the chemical modification of SMA is successful．GPC and DSC results of the polymers obtained show that although the molecular weight of these polymers decreased a little in the chemical modification process,the thermal stability of these polymers was improved．On the other hand the fluorescence of these polymers can be quenched by the acidity because of the alkalescence of the organic heteroring containing nitrogen．These novel polymers can emit strong fluorescence and kept the excellent properties of SMA too．This is a convenient method to produce the fluorescent materials．
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发布时间：2021-03-19 - 摘要：The syndiotactic polypropylene (sPP) with high bulk density and sphere-like was prepared in bulk process by syndiospecific metallocene catalyst,which was synthesized and supported on silica by ourself. To avoid the active center of the metallocene catalyst leaching from silica surface that would foul reactor in polymerization,the blend of methylaluminoxane (MAO) and metallocene catalyst was deposited on silica treated by MAO first,then washing three times at least by hexane．The polymerization was carried out in 5 L reactor．The results verified that the high polymerization activity and syndiospecification of the metallocene catalyst were preserved after being supported． The polymerization activity and the pentad concentration of sPP are more than 1066 g sPP／molZr·h and 75％,respectively. The morphology and distribution of sPP particles were modified remarkably．Through studying the polymerization process,the effects of the polymerization temperature and the catalyst concentration on the polymerization results were inspected including polymerization activity,polymer morphology and the bulk density of polymer. When polymerization activity is in the range of 3～4×106 g sPP／molZr·h,the sphere-like sPP with weight average molecular weight (Mw) between 15～45×104 and the bulk density between 0.35～0.45 g／cm3 was obtained.
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发布时间：2021-03-19 - 摘要：As the miscible polymer blend systems,poly(arylene ether ketone)s (PAEK)／poly(ether imide) (PEI) blends had attracted many researches．Because almost all the commercial PAEK are the semi-crystalline polymers,no amorphous PAEK and PEI blends had been researched．Poly(phthalazinone ether ketone ketone) (PPEKK),a novel high heat resistant performance thermoplastic,is an amorphous PAEK．The miscibility of PPEKK／PEI blends was investigated using ternary-solution methods and differential scanning calorimetry(DSC)．The ternary-solution methods results indicated that the blends are miscible because chloroform solution of blends is uniform after being kept more than 10 days．A single glass transition temperature(Tg) for different compositions blends was showed by DSC results and the relationship of Tgs and composition is in agreement with Gordon-Taylor equation which is applied for the miscible polymer blends．Scanning electron microscopy for as-quenched PPEKK／PEI blend sample further proved the miscibility of the blends．The FT-IR results indicated that the interaction of two polymers in the blends is weak,therefore,the miscibility of the blends should be contributed to the repulsion between the two components is weaker than that in themselves. The tensile properties of blends’film samples were tested and the tensile modulus,tensile strength and elongation at break of some composition blends are larger than that of pure resins,which can be explained by the miscibility of the blends．
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发布时间：2021-03-19 - 摘要：The fullerenes chloride,(C60Cln/C70Cln,was used as a novel coupling agent in n-BuLi initiated anionic polymerization of butadiene(Bd)．Its coupling behavior was investigated by comparing with the commonly used coupling agent SiCl4．The broader polydispersity of the coupling products and a new peak in GPC chromatograms demonstrated that coupling reactions happened and polybutadiene chains were covalently bonded to the molecule of C60Cln/C70Cln．But the coupling efficiency needs to be improved．The intrinsic viscosity of the coupling products ([η]) was also measured．Double peaks in the coupling agent curves appeared when C60Cln/C70Cln was used,while a single peak in the coupling agent curves occurred when SiCl4 was used．The results above showed that C60Cln/C70Cln had the specific coupling mechanisms which were different from SiCl4．Two coupling mechanisms of C60Cln/C70Cln including addition and substitution were deduced．The experiment also revealed that in the anionic polymerization of Bd,the molecule C60 could influence the polymerization．A new living center formed in the reaction system by n-BuLi and C60 might be able to initiate the polymerization of Bd,which increased the products’molar mass and broadened polydispersity．The structure of the star-shaped products with polybutadiene as arms and C60Cln/C70Cln as core should be studied further.
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发布时间：2021-03-19
Research Bulletin
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