最新刊期
卷 ， 期 3 ， 2011
- 摘要：In order to explore the coupling effects of second shear flow and temperature fields on the formation as well as the evolution of crystal morphologies of high-density polyethylene (HDPE),the crystal morphologies of the parts obtained by multi-fluid multi-injection molding (MFMIM) were investigated.The main feature of MFMIM is that the polymer melts in two different injection units are injected sequentially into the cavity to form an encapsulated sandwichstructure product.Polarizing light microscopy (PLM) results showed that some peculiar microstructures (e.g.cylindritic structures and ring-banded spherulites) were generated in the skin layer of the MFMIM parts.With the aid of scanning electronic microscopy (SEM),a detailed description of cylindritic structure was obtained,which showed that the cylindritic structure consisted of some ring-banded spherulites.For comparison,the crystalline morphology of the sample molded by conventional injection molding(CIM) was also investigated.Different from the MFMIM parts,there were not observed any ringbanded spherulites or cylindritic structures in CIM parts except the common spherulites.And there was not a significant skin-core structure formed due to the higher temperature of the mold.Based on the comparison between the experimental results of the MFMIM parts and those of the CIM counterparts,it was concluded that the main reasons for ring-banded spherulites and cylindritic structures arising in the skin layer of MFMIM parts were the shearing and the complex thermo-mechanical fields provided by the secondary melt penetration process.Therefore,on the basis of the previous results,the mechanisms of ring-banded spherulites and cylindritic structures formation were discussed.关键词：Multi-fluid multi-injection molding
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发布时间：2021-03-19
Rapid Communications
- 摘要：A series of polycaprolactone-b-poly(ethylene glycol) (PCL-b-PEG) and star-branched polycaprolactone (SPCL) polymers were successfully synthesized by ring-opening polymerization method,and the resulting polymer were characterized using 1H-NMR.The results of GPC indicate that the copolymers and star-branched polymers have low polydispersity index and their molecular weight is accordance with the 1H-NMR results.Phase separation method was used to prepare self-assembling aggregates of PCL-b-PEG with SPCL and without SPCL.The self-assembling aggregates were characterized by turbidity,dynamic light scattering (DLS),SEM and FTIR.The results of SEM and DLS proved that with the SPCL added the diameter of the self-assembling aggregates became larger than that of the aggregates without the SPCL,and the results of FTIR also proved PCL-b-PEG and SPCL could self-assemble together.The length of PEG and PCL in PCL-b-PEG is an important factor to influence the diameter of the self-assembling aggregates,and with decreasing the length of PEG or increaing the length of PCL the diameter became larger.The diameter of the self-assembling aggregates depended on the length,the number of arms and the amount of SPCL,and the diameter increased with the length and the arm number of SPCL.The results of the research may provide some information for the encapsulation of hydrophobic drugs in amphiphilic copolymers.关键词：Polycaprolactone-b-poly(ethylene glycol)
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发布时间：2021-03-19 - 摘要：The functionalization reaction of ethylene-propylene-diene monomer rubber (EPDM) and high-density polyethylene (HDPE) with maleic anhydride (MAH) during melt extruding through the high shear stress induced initiation by increasing the screw rotation speed of twin-screw extruder and changing the reaction temperature was investigated.With increasing the screw rotation speed,the scission of EPDM and HDPE molecule chains can be caused to form macroradicals and the reaction of EPDM/HDPE with MAH can be realized.The functionalized product (EPDM/HDPE)-g-MAH with higher percentage of grafting and better melt flow rate and lower gel content was prepared.The effects of (EPDM/HDPE)-g-MAH as a compatilizer on the compatibility,morphology and the mechanical properties of PA66/EPDM/HDPE blends were studied.The results showed that (EPDM/HDPE)-g-MAH greatly improved the compatibility of the blends.With an increase in (EPDM/HDPE)-g-MAH content in the blend,the size of minor component domains decreased greatly.And the Izod impact strength and elongation at break of the blends improved obviously.关键词：EPDM/HDPE共混物
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发布时间：2021-03-19 - 摘要：The characteristics of depolymerization of polycarbonate(PC) in sub-critical water were investigated in the range of 260~340℃ and 5~60 min by using a high-pressure batch autoclave reactor.It was found that PC could be effectively depolymerized in sub-critical water.The main products were bisphenol A（BPA）and phenol,which were analyzed by FTIR,SEM,GC/MS and GC.It was found that the temperature and reaction time were important factors in the process of depolymerizaition.Swelling process of PC played an important role in this hydrolysis reaction,which occured in the region 280 ~ 300℃ accompanied by the remarkable hydrolysis.With the raising of the temperature and the reaction time,the yield of bisphenol A was increased at first and then reduced.Bisphenol A was unstable in the sub-critical water,it would further decompose into phenol,p-tert-butylphenol,p-isopropenylphenol etc.The result showed that at reaction temperature 300℃,reaction pressure 8.7 MPa and reaction time 45 min,the PC could be depolymerized completely with the yield of BPA and phenol were 36.88% and 31.16%,respectively.Based on the qualitative and quantitative analyses of the products,the reaction mechanism,i.e.random scission and hydrolytic reaction occurred simultaneously during the process of depolymerizaition of PC was proposed.The results of kinetic analysis indicated that the depolymerization followed a pseudofirstorder kinetics and the activation energy of PC depolymerizaition in sub-critical water obtained from Arrhenius equation was 125.7 kJ . mol-1.关键词：Sub-critical water
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发布时间：2021-03-19 - 摘要：Polymethyl methacrylate/tetrabutyl titanate(PMMA/TBT) organic-inorganic hybrid films with honeycomb patterns were prepared by breath figures method.The casting solutions were prepared by adding directly TBT into the chloroform solutions of polymethyl methacrylate.The prepared PMMA/TBT film was used as precursor film to prepared honeycomb patterned TiO2 film.The prepared films were characterized by SEM,FTIR and XRD.Effects of PMMA concentration,PMMA/TBT ratio and hydrolysis inhibitor were investigated.It was showed that when the PMMA concentration was too low,the condensed water drop could not be wrapped and stabled by PMMA,on the other hand,when the PMMA concentration was too high,the condensed water drop could not sink into the solution and gathered on the surface,resulting in combination of condensed water drops,the perfect honeycomb patterned films were obtained at the suitable PMMA concentration range from 20 mg/mL to 30 mg/mL.It was also found that the honeycomb patterned structure could not be formed at PMMA/TBT ratio not more than 1 owing to the increase in the hydrophilicity of casting solutions with more TBT.The honeycomb patterned pores were not perforative.The perfection of honeycomb structure could be improved and the diameter of the pores could be decreased by addition of isopropanol to depress the thorough hydrolysis of TBT,and the suitable isopropanol concentration was less than 10 mg/mL.It was deduced from FTIR and XRD results that,during the formation of the film,partial hydrolysis of TBT occurred and titanium hydrogen oxide hydrates were formed.These hydrates combined to the ester group of PMMA by covalent or hydrogen band,as a result,the inorganic components were anchored to PMMA.This hybrid film could be used to prepare honeycomb patterned porous TiO2 films.关键词：Breath figures;Ordered porous film;Honeycomb pattern;Organic-Inorganic hybrid film
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发布时间：2021-03-19 - 摘要：Five kinds of unsaturated carboxylic acid salts of chitosan were prepared by the semidry way including chitosan salicylate (a1),chitosan benzoate (a2),chitosan cinnamate (a3),chitosan acrylate (a4) and chitosan itaconate (a5).The products were characterized via FTIR and UV,the content of carboxylic acid in the unsaturated carboxylic acid salt of chitosan was determinated by the Kjeldahl method.The results showed that unsaturated carboxylic acid salts of chitosan were combined with salt bond between amino and carboxyl,the content of carboxylic acid in the unsaturated carboxylic acid salts was ranged from 40% to 70%.The crystalline morphology of these unsaturated carboxylic acid salts of chitosan were obtained by polarized optical microscopy.The results showed that the films of a2 and a5 obtained by a casting solvent vaporation technique had formed fractal crystal at 25℃and RH = 65%.The crystalline morphology was closely related to the structures of unsaturated carboxylic acid salts of chitosan.The fractal crystal of a2 showed that the extended molecular chains were parallel to the long axis.The fractal crystal of a5 showed that the extended molecular chains were perpendicular to the long axis.The methods for controlling aggregation behavior of unsaturated carboxylic acid salts of chitosan had also been studied.It was feasible for the inter-conversion between aggregation and crystallization.The crystallization process of chitosan unsaturated carboxylic acid salts was explained by fractal theory,and the results showed that its aggregation behavior abide by the model of diffusions-limited aggregation.关键词：Unsaturated carboxylic acid salts of chitosan
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发布时间：2021-03-19 - 摘要：A series of crosslinked aliphatic polyurethane (PU) elastomers with various crossslink densities were synthesized by the reaction of isophorone diisocyanate (IPDI) with polyether diol,trimethylolpropane (TMP) and 1,4-butanediol (BDO) through one step method.The results showed that the crosslink density of PU elastomers exhibited a linear relationship to the content of TMP,while the content of hard segments of PU elastomers was fixed at 40 wt%.With the increase of the crosslink density of the PU elastomers,the glass transition temperature (Tg) value of the hard segment domains in the PU dropped significantly from 32℃ to 21℃,the Tg value of the soft segment domains in the PU dropped slightly form -47℃ to -48℃,and the degree of Hbonded urethane carbonyl in the PU decreased from 83% to 63%,which indicated that the micro-phase miscibility of the PU elastomers was enhanced.With the increase of the crosslink density of the PU elastomers,the TGA results showed that the onset decomposition and the maximum decomposition temperature of the PU elastomers increased from 285℃ to 319℃ and 325℃ to 349℃ respectively,which indicated that the thermal stability of the PU elastomers was also improved.The mechanical test indicated that the Youngs modulus,modulus at 100% extension and Shore A hardness of the PU elastomers significantly increased with the increase of the crosslink density of PU,while the elongation at break decreased.关键词：Aliphatic polyurethane elastomer
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发布时间：2021-03-19 - 摘要：The novel graft copolymers of (poly(a-co-b),(a:propiolic acid L\|menthol ester; b:propiolic acid polyethylene glycol monomethyl ether ester)) having Cchirality and hydrophilic macromolecules as pendant groups were synthesized via copolymerization of monomer a and monomer b by using (nbd)Rh+［6-C6H5B-(C6H5)3］ as catalyst.The structure of copolymers was characterized by FTIR.Moderate molecular weights (Mn) (13000~15000) and Mw/Mn (21~22) of copolymers were measured by GPC.The maximum amount of MPEG for successful copolymerization of copolymers was 20 mol%.The optical activity and secondary structure of the copolymers were characterized by specific rotations (［］D) and circular dichroism (CD) spectra.The copolymers with relatively low yields (32.3%~46.6%) exhibited high optical activity in contrast to chiral monomer,which accorded with the Chiral Amplification effect.All the copolymers formed single helical conformation in despite of adding the long chain of MPEG.Certainly,the optical activity of copolymers decreased with the increase of MPEG content.The helical conformation of the copolymers kept the better stability in CHCl3 comparing to other three selective solvents.As the time delay,the optical activity of the copolymers decreased due to their instability.By adding the hydrophilic chain of MPEG,rigid and flexible chain were linked finely and formed the hydrophilic/hydrophobic interaction,which provided the best driving force for selfassembly behavior.关键词：Polyacetylenes
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发布时间：2021-03-19 - 摘要：The vermiculite was chosen as the carrier of bactericide,and it was modified by being carried with Ag or/and intercalated with hexadecyl trimethyl ammonium bromide (HDTMA?Br) by ionic exchange,thus three types of antibacterial vermiculite were obtained.The antibacterial vermiculite was mixed with PA6 through melting to prepare the PA6/vermiculits composites.The antibacterial ability and physical mechanical properties of the composites were tested,and vermiculites dispersion in PA6 and tensile fracture were observed by TEM and SEM.The composite containing Ag-loaded and organointercalated vermiculite have obvious bacteriostatic ring,and its antimicrobial ratio to Escherichia coli and Staphylococcus cereus is respectively 94% and more than 99.9%.The tensile and flexural properties of PA6 were improved,in comparison with the pure PA6,the elastic modulus,tensile strength,flexural modulus and flexural strength of the composite increased by 126.8%,17.4%,33.1% and 30.3%,respectively.The thermal distortion temperature rose about 51 K.The dynamic storage modulus was increased largely,mechanical loss was lowered.TEM photographs showed that the vermiculite dispersed evenly in PA6 matrix and was exfoliated to about 200 nm in length and about 10 nm in width,so the nanocomposites had formed between vermiculite and PA6.关键词：PA6
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发布时间：2021-03-19 - 摘要：Effects of comb-type polycarboxylate grafted copolymers such as methacrylic acid-methoxy polyethylene glycol monomethacrylate (MAA-MPEGMA) copolymers,methacrylic acid-polyethylene glycol monoallyl ether (MAA-APEG) copolymers and acrylic acid-polyethylene glycol monoallyl ether (AAAPEG) copolymers and polyacrylic acid (PAA) homopolymer on dispersion of gypsum particles and set time of gypsum slurries were studied.Polymers with short side-chain length,low molecular weight or high density of charge have improved dispersing effects and longer set time.In all polymers studied,PAA homopolymer with highest density of charge has the best dispersing effects and longest set time.Copolymers containing very short length of both side chain and backbone have better dispersion ability and longer set time.And copolymers containing anchoring groups of acrylic acid have better dispersing ability and longer set time than that of copolymers containing anchoring groups of methacrylic acid.Effects of chemical structure on dispersion of gypsum and dispersion-adsorption mechanisms were also explained and discussed from the point of surface and interface chemistry.It shows that the dispersing mechanism of polycarboxylate superplasticizer to gypsum powder is realized through affecting set time and hydration reaction of gypsum with water, and is more like the electrostatic repulsion effect than the steric hindrance.关键词：Polycarboxylate
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发布时间：2021-03-19 - 摘要：Poly(o-aminophenol) (POAP) grafted by poly(-caprolactone) (PCL),with the grafted rate of 68.7% calculated by mass gain method,has been synthesized successfully through the reaction of poly(o-aminophenol) and caprolactone,with stannous octoate as catalyst,via ring-opening polymerization in anhydrous toluene solution.The poly(o-aminophenol) was synthesized directly by o-aminophenol with ammonium persulfate.The structure of the final grafted polymer was characterized and verified by means of nuclear magnetic resonance (NMR),Fourier transform infrared spectroscopy (FTIR),thermo gravimetric analysis (TGA),X-ray diffraction (XRD),cyclic voltammetry (CV),gel permeation chromatography(GPC) and UV-Vis spectrophotometry (UV-Vis).The molecular weight of the grafted polymer is ca. 1.4104 with polydispersity of 1.03 determined by GPC with DMF as eluent.Due to the introduced PCL segments in the grafted polymer,the thermal stability and electrochemical stability of the final polymer are superior to that of the poly(oaminophenol) as well as its solubility is improved,thus can be dissolved in some common organic solvents,such as ethanol,toluene,THF,DMF etc.Especially,the color of the polymers DMF solution shows obvious changes at different pH values.The color of the polymer solution can be changed from bright light brown to light brown (from pH 7 to 2) and from bright light brown to violet (from pH 7 to 12).More importantly,the process is reversible.The sensibility to pH value gives the polymer more opportunity to be used as sensor materials.关键词：Poly(o-aminophenol)
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发布时间：2021-03-19 - 摘要：Monodispersed carboxyl-containing PSt seed latex with the diameter of 360 nm was first synthesized via batch emulsifier-free emulsion polymerization,and the positively charged PSt latex particles with surface reactive ethoxylsilyl groups were then prepared in the medium of ethanol and water using -aminopropyl triethoxysilane (KH-550) as modifier,then PSt/SiO2core-shell composite microspheres were obtained by dropwise adding tetraethoxysilane (TEOS) into the above system.Influences of pH and TEOS amount on the morphology of PSt/SiO2 core-shell composite microspheres were investigated using TEM and SEM.Results showed that the PSt/SiO2core-shell composite microspheres were generated only under alkaline conditions.When the amounts of PSt seed particles and TEOS was 1.5 g and 5.0 g,respectively,and pH was controlled at 8.5,the encapsulation of PSt seed particles with SiO2 was intact,and the uniform SiO2 shell with about 35 nm was obtained,and after that,the percentage of the composite microspheres partially encapsulated by SiO2 increased with the increase of pH value.With the increase of TEOS amount from 2.5 g to 15 g,the thickness of PSt/SiO2core-shell composite microspheres gradually increased from 17 nm to 68 nm,but their surface gradually became rough.关键词：PSt/SiO2composite microspheres
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发布时间：2021-03-19 - 摘要：The melting and non-isothermal melt-recrystallization behaviour of poly(vinylcyclohexane)-b-poly(ethylene)-b-poly(vinylcyclohexane)(PVCH-b-PE-b-PVCH) solution crystallized sample,which was obtained after isothermal solution crystallization,were investigated by means of DSC.It was found that different with the PVCH-b-PE-b-PVCH melt crystallized sample,the solution crystallized sample possessed a higher melting temperature in the heating process and multiple crystalline peaks in the non-isothermal melt-recrystallization process.In the solution crystallization step of the solution crystallized sample,due to the dissolution of PVCH blocks in p-xylene the extent of the PE confined crystallization is reduced,forming more perfect PE crystals,and thus the melting temperature is higher than that of the melt crystallized sample.On the same time,the crystallization of PE blocks in solution also causes respective aggregation of PE and PVCH blocks,accordingly an initial microphaseseparated structure is formed.The segment mobility of PE blocks is relatively improved in the initial microphase-separated structure,resulting in the partially confined crystalline peak crystalline peak Ⅱ and the completely confined crystalline peak at low temperature crystalline peak Ⅲ.From the comparison of the slow cooling experiment and the quenching experiment,it was found that crystalline peak Ⅰ at high temperature related to the microphaseseparated ordered structure of the block copolymer.The formation of the ordered structure induces the further aggregation of PE blocks,improving the PE crystallization,and thus PE blocks could crystallize at the high temperature.The confined crystallization behavior of the block copolymer is influenced by the microphaseseparated structures of the block copolymer,resulting in non-isothermal multiple crystalline peaks of the PVCH-b-PE-b-PVCH solution crystallized sample.The corresponding relation between the phase structures and the multiple crystalline peaks was discussed,and the formation reason of the non-isothermal multiple crystalline peaks was further clarified.关键词：Crystalline-noncrystalline block copolymer
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发布时间：2021-03-19 - 摘要：A novel kind of Sm(Ⅲ) complex with 2-mercaptobenzimidazole was prepared.The antioxidative properties and mechanism of the Sm(Ⅲ) complex in the natural rubber (NR) vulcanizates was investigated by attenuated total-reflectance Fourier transform infrared (FTIR-ATR) spectroscopy and thermogravimetric analysis.The thermo-oxidative stability of the NR vulcanizates was found to be improved markedly by the addition of the Sm(Ⅲ) complex.The FTIR-ATR results showed that the Sm(Ⅲ) complex retarded aging and allowed the oxidation products to increase more slowly.The Sm(Ⅲ) complex had no effect on the thermal decomposition of the NR vulcanizate,but it improved the thermo-oxidative stability significantly.The antioxidant effect of the Sm(Ⅲ) complex was superior to that of antioxidant MB and antioxidant 4010NA.It could be attributed to the thioether bonds which can decompose the hydroperoxide and the Sm(Ⅲ) ions which can capture and inactivate the oxy radicals.The apparent thermo-oxidation activation energy (E) of the NR vulcanizates was calculated by the Kissinger and Flynn-Wall-Ozawa methods,respectively.The results showed that the NR vulcanizate with the Sm(Ⅲ) complex had higher thermo-oxidation activation energy than that of the samples with antioxidant MB and antioxidant 4010NA.关键词：Sm(Ⅲ) complex
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发布时间：2021-03-19 - 摘要：Polyfluorene flims were synthesized electrochemically by direct anodic oxidation of fluorene in the mixed electrolyte of acetic acid and borontrifluoride diethyl etherate (BFEE) (5∶4 by volume).The oxidation potential of fluorine in the mixed electrolyte was measured to be only 0.48 V versus Pt,which was much lower than that determined in acetonitrile containing 0.1 mol L-1 tetrabutylammonium tetrafluoroborate (TBATFB).The conductivity of polyfluorene from this medium was 0.5 S cm-1,which was higher than that determined in pure BFEE (0.25 S cm-1).The polyfluorene films obtained from acetic acid and BFEE (5∶4 by volume) showed good electrochemical behavior and stability in concentrated sulfuric acid.FTIR,1H\|NMR spectral results and theoretical studies demonstrated that the electropolymerization of fluorene mainly occurred at the 2,7-positions.Compared with that obtained from the mixed electrolyte without PEG1000,the polymer obtained from acetic acid and BFEE (5∶4 by volume) with PEG1000 showed a red shift in the fluorescence spectra,a better thermal stability and a more ordered stack of the platelet in appearance,but the thermal stability of the polymer obtained from acetic acid and BFEE (5∶4 by volume) was better than that for the one made in pure BFEE.At the same time,the fluorescence spectra results indicated that the soluble polyfluorene electrosynthesized from acetic acid and BFEE (5∶4 by volume) was a good blue light emitter which may find application in optoelectronics.关键词：Acetic acid;Borontrifluoride diethyl etherate;Polyfluorene;Electrochemical polymerization;PEG1000
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发布时间：2021-03-19
Research Article
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