In this paper, the capabilities of grafting acrylonitrile (AN) onto starch initiated by Fe(III)-TU, V(V)-TU, Cr(VI)-TU, Mn(VII)-TU redox systems were compared in the presence of sulfuric acid of different concentratio...In this paper, the capabilities of grafting acrylonitrile (AN) onto starch initiated by Fe(III)-TU, V(V)-TU, Cr(VI)-TU, Mn(VII)-TU redox systems were compared in the presence of sulfuric acid of different concentrations. It was shown that the grafting capability of Mn(VII)-TU is the highest in these initiating systems. Using Mn (VII-TU as initiator, the effects of various acids (HClO4, H2SO4, HNO3, HCl) on the graft copolymerization of acrylonitrile onto starch were discussed, and the capabilities of graft copolymerization of methyl methacrylate (MMA), acrylamide (AM), acrylic acid (AA) onto starch were investigated. The experimental results show that the order of the influences of different acids is HClO4 > H2SO4 > HNO3 > HCl, and the order of grafting capabilities of different monomers grafted onto starch is MMA > AN > AM > AA. The structure and morphology of graft, copolymers were studied with infrared spectroscopy and scanning electron microscopy. The size, shape and roughness of surface of the grafted starch granules are changed after grafting.展开更多
With potassium persulfate (KPS) as initiator, graft copolymerization of ethyl acrylate (EA) onto water-soluble hydroxypropyl methylcellulose (HPMC) was investigated in aqueous medium. Effects of monomer concentration,...With potassium persulfate (KPS) as initiator, graft copolymerization of ethyl acrylate (EA) onto water-soluble hydroxypropyl methylcellulose (HPMC) was investigated in aqueous medium. Effects of monomer concentration, initiator concentration, matrix concentration, and reaction temperature on the percentage of grafting (G) and grafting efficiency (G_E) were studied. The results show that G and G_E values both increase with the the increase of EA concentration and KPS concentration; when raising HPMC concentration from 0.12 mmol/L to 0.47 mmol/L, G decreases, while G_E increases;and when raising reaction temperature from 50 ℃ to 65 ℃,G increases, but G_E decreases. In addition, the graft copolymers were characterized by Fourier transform infrared (FTIR) spectra and transmission electron microscopy (TEM) methods.展开更多
2,2,3,3,4,4,5,5-Octafluoropentyl acrylate was grafted onto silk fiber in a two-step heterogeneous system through the vinyl bonds of acryloyloxyethyl isocyanate modified on the silk.The grafted copolylner was analyzed ...2,2,3,3,4,4,5,5-Octafluoropentyl acrylate was grafted onto silk fiber in a two-step heterogeneous system through the vinyl bonds of acryloyloxyethyl isocyanate modified on the silk.The grafted copolylner was analyzed by FTIR and WAXD,and the results revealed that the fluoroacrylate was successfully grafted onto silk fiber and the crystalline structure of silk fibroin withβ-sheet structure was not changed after graft copolymerization.The FT-IR corrected method was used to simulate the grafting yield onto sil...展开更多
Dissolution and homogeneous graft copolymerization of cellulose were performed in an ionic liquid 1-allyl-3-methylimidazolium chloride （AmimCl） with 2-hydroxyethyl methacrylate. The synthesized AmimCl and cellulose ...Dissolution and homogeneous graft copolymerization of cellulose were performed in an ionic liquid 1-allyl-3-methylimidazolium chloride （AmimCl） with 2-hydroxyethyl methacrylate. The synthesized AmimCl and cellulose graft copolymers were characterized by FTIR, ^1 H-NMR and XRD spectroscopy. The results show that AmimCl dissolved cellulose directly by destroying intermolecular and intramolecular hydrogen bonds in cellulose and the crystalline form of cellulose was transformed from cellulose Ⅰ to cellulose Ⅱ after regeneration from AmimCl. The best synthetic condition of the cellulose-graft-P （2-hydroxyethyl methacrylate） was that cellulose 0.5 g, 2-hydroxyethyl methacrylate 3.00 g and initiator ammonium persulfate 0.05 g reacted for 180 min at 60℃; the rate of grafting reached 77.3%.展开更多
The effects of magnetic field on the graft ratio and stereoregularity of grafts of PVA-g-MMA in the presence ofbenzophenone during UV irradiation are discussed. By means of IR, it was found that the graft ratio was in...The effects of magnetic field on the graft ratio and stereoregularity of grafts of PVA-g-MMA in the presence ofbenzophenone during UV irradiation are discussed. By means of IR, it was found that the graft ratio was increased with the increment of magnetic field strength. Furthermore, application of relative weak magnetic field of 0.4 Tesla had been shown to substantially enhance the stereo-regularity of graft copolymer. The maximum stereo-regularity appeared when the graft ratio approached to 85% with the magnetic field of 1.2 Tesla (T). The resistance to moisture and heat resistance of the grafted copolymer in the presence of magnetic field were also improved.展开更多
To enhance the polarization of starch, the oxidized starch-BA-MAA-Gd copolymer was synthesized by radical graft copolymerization. The structure of the graft copolymer was determined by IR, scanning electron microscopy...To enhance the polarization of starch, the oxidized starch-BA-MAA-Gd copolymer was synthesized by radical graft copolymerization. The structure of the graft copolymer was determined by IR, scanning electron microscopy, state thermal analysis and X-ray diffraction. The electrorheological properties of the graft copolymer were also investigated. The results show that shear stress increases with the increase of the graft copolymer loadings and the electric field intensity.展开更多
K2 S2 O8 and rare earths （RE） were used as initiators to prepare superabsorbents by graft copolymerization of acrylic acid （ AA ） onto corn starch. The effects of monomer concentration, initiator K2 S2 O8 concentr...K2 S2 O8 and rare earths （RE） were used as initiators to prepare superabsorbents by graft copolymerization of acrylic acid （ AA ） onto corn starch. The effects of monomer concentration, initiator K2 S2 O8 concentration, cross-linker concentration, reaction temperature and the concentration ratio of RE and K2 S2O8 on the graft copolymerization were studied in terms of the water absorption capacity of superabsorbents. Results indicate that the optimum conditions obtained for the grafting of AA onto 5g starch are as follows： AA of 75. 773 g/L, K2S20s of 0. 437 g/L, RE of 0. 874 g/L, cross-linker of 0. 381 g/L and temperature of 70 ℃. The maximum water absorption capacity obtained is 740 g/g. The new method of graft polymerization is easily proceeded and controlled. The graft copolymers were characterized by infra-red spectroscopy, scanning electron microscopy and TG. Results characterized by IR and SEM give strong evidence for grafting of AA onto corn starch, and those characterized by TG reveal that the grafting of AA improves the theimostability of corn starch.展开更多
Natural rubber(NR)grafted with 2-ethylhexyl acrylate(2-EHA)and methacrylic acid(MAA,collectively NR-g-PEHA/MAA)was synthesized by emulsion polymerization.Tetraethylenepentamine and cumene hydroperoxide were used as re...Natural rubber(NR)grafted with 2-ethylhexyl acrylate(2-EHA)and methacrylic acid(MAA,collectively NR-g-PEHA/MAA)was synthesized by emulsion polymerization.Tetraethylenepentamine and cumene hydroperoxide were used as redox initiators.The successful grafting of 2-EHA and MAA onto NR was confirmed by Fourier transform infrared spectroscopy.The morphology of the NR latex particles was observed by transmission electron microscopy.The effects of reaction temperature,initiator dosage,feeding mode,and hard monomer content on the mechanical properties of the modified NR film were investigated.Grafted polymer chains were unevenly wrapped on the outside of NR particles,and smaller particles were more easily grafted.Crosslinking was characterized using a toluene swelling method.Thermal stability and glass transition temperature were examined by differential scanning calorimetry and thermogravimetric analysis.The results showed that the thermal stability of NR-g-PEHA/MAA had been improved,and the glass transition temperature(Tg)was unchanged.展开更多
Grafting copolymerizations of methyl acrylate(MA) and ethyl acrylate(EA) onto corn starch, respectively, initiated by potassium persulfate-sodium thiosulphate (KPS-STS) redox system, were studied. The structures of po...Grafting copolymerizations of methyl acrylate(MA) and ethyl acrylate(EA) onto corn starch, respectively, initiated by potassium persulfate-sodium thiosulphate (KPS-STS) redox system, were studied. The structures of poly(MA)-g-starch and poly(EA)-g-starch were characterized by IR, SEM and X-ray diffraction. Experimental results show that KPS-STS is an efficient initiation system for grafting of MA and EA onto corn starch. The maximum percent grafting was obtained at [KPS] of 6.0× 10~3 mol/L, [STS] of 1.8× 10 5 mol/L, [M] of 6. 0× 101 mol/L, S:L=4:100 at 40℃ for 6 h. The reactivity order is MA>EA.展开更多
The graft copolymerization of acrylonitrile (AN) onto starch under the initiation of potassium permanganate was investigated. The effect of various reaction conditions on the graft copolymerization was studied. The re...The graft copolymerization of acrylonitrile (AN) onto starch under the initiation of potassium permanganate was investigated. The effect of various reaction conditions on the graft copolymerization was studied. The relationships between the grafting rate and the initiator concentration of potassium permanganate, monomer acrylonitrile and backbone starch, as well as reaction temperature were established. The oxidation reaction of starch with manganic ions and valence changes of manganic ions during the graft copolymerization were discussed. The results show that manganic ion Mn 7+ underwent a series of valence changes during the graft copolymerization: Mn(Ⅶ) → Mn(Ⅳ) → Mn(Ⅲ) → Mn(Ⅱ). The grafting rate of the graft copolymerization of acrylonitrile onto starch is also given.展开更多
The starch/D,L-lactide graft copolymers were synthesized by reacting D,L-lactide with corn starch in N,N-dimethylacetamide (DMAM) in the presence of triethylamine (NEt3) and anhydrous lithium chloride. The effect of r...The starch/D,L-lactide graft copolymers were synthesized by reacting D,L-lactide with corn starch in N,N-dimethylacetamide (DMAM) in the presence of triethylamine (NEt3) and anhydrous lithium chloride. The effect of reaction time and the molar ratio of D,L-lactide to glucose structural unit of starch on monomer conversion(C%), graft (G%) and graft efficiency (GE%) were studied. The C%, G% and GE% could approach 37.3%,179.7% and 68.0%, respectively when the molar ratio of D,L-lactide to glucose structural unit of starch is 10:1 and the graft copolymerization was carried out at 80-85℃ for 4 hours under nitrogen atmosphere. The Fourier transforms infra-red (FTIR) spectroscopy, differential scanning calorimetry (DSC) and X-ray diffraction (XRD) spectroscopy were used in order to characterize the graft copolymers. FTIR spectra show that absorption band at 1740 cm-1 confirmed the formation of ester bond, indicating the starch /D,L-lactide graft copolymers were produced, the DSC characteristic results show the melting temperature of the graft copolymer were elevated slightly as the molar ratio of D,L-lactide to glucose structural units of starch increased and the X-ray diffraction spectra show the synthesized graft copolymers were amorphous. The degradability of graft copolymer was tested with the aid of acid, alkali and microbe such as bacillus subtilis and staphylococcus aureus. The results of water resistance show the graft copolymer produced can be used as a component of impermeable coating for cardboard.展开更多
The graft copolymerization of acrylic acid (AA) with unswollen and swollen ramie fibers using chromic acid (H 2CrO 4) as the initiator has been studied in the presence of air. The effects of initiator concentration,...The graft copolymerization of acrylic acid (AA) with unswollen and swollen ramie fibers using chromic acid (H 2CrO 4) as the initiator has been studied in the presence of air. The effects of initiator concentration, monomer concentration, perchloric acid (HClO 4) concentration, time of polymerization, reaction temperature, and amount of ramie fibers on the graft percentage have been found out. The graft copolymer was characterized by IR spectra, scanning electron microscopy(SEM), differential thermal analysis (DTA), and thermogravimertric analysis (TGA).展开更多
Pentaerythritol triacrylate （PETA） was successfully grafted onto the plasma-treated isotactic polypropylene （iPP） via the in situ melt processing. The X-ray photoelectron spectroscopy （XPS） results showed that t...Pentaerythritol triacrylate （PETA） was successfully grafted onto the plasma-treated isotactic polypropylene （iPP） via the in situ melt processing. The X-ray photoelectron spectroscopy （XPS） results showed that the hydroxyl and carbonyl groups, and peroxides could be generated via plasma treatment. The content of free radical in plasma-treated iPP （PiPP） was measured by 2,2-diphenyl-1- picrylhydrazyl （DPPH）. It was found that the resulting peroxides induced the grafting copolymerization of PETA onto iPP, and the grafted PETA promoted the formation of β-crystal in PiPP, which was evidenced by Fourier transform infrared spectroscopy （FTIR）, differential scanning calorimetry （DSC） and wide-angle X-ray diffraction （WAXD） measurements, respectively.展开更多
Thermosensitive core-shell particles were synthesized through graft copolymerization of N-isopropylacrylamide with[3-(methacryloxy)propyl]trimethoxysilane(MPT)coupled on the surface of ultrafine silica beads.The copol...Thermosensitive core-shell particles were synthesized through graft copolymerization of N-isopropylacrylamide with[3-(methacryloxy)propyl]trimethoxysilane(MPT)coupled on the surface of ultrafine silica beads.The copolymerization was carried out using polyvinyl alcohol as a surfactant,water and cyclohexanol as mixed solvent,and 2,29-azobis(isobutyronitrile)as an initiator.The effect of surfactant concentration and the composition of the mixed solvent on the graft rate were investigated.The structure of modified silica was confirmed by infrared spectra.Differential scanning calorimetry(DSC)has revealed the thermosensitivity of the particles.The thermosensitive particles were used as packing materials of high performance liquid chromatography(HPLC)columns for separating naphthalene derivatives.Satisfactory separation was obtained by controlling the temperature of the column.In contrast,the packing material of silica-MPT has no such separation efficiency due to the lack of thermosensitivity.The effect of the composition of the mobile phase on the separating efficiency was also investigated.The temperature-controlled separation was effective only when the water content was higher than 90%(v/v)in the water-methanol mobile phase.The mechanism for the temperature-controlled separation is attributed to a polarity change of poly(N-isopropylacrylamide)which undergoes volume phase transition on the silica surface as the temperature increases.展开更多
The surface of polypropylene （iPP） is modified with glow discharge plasma of Ar, so that the modified surfaces of iPP films are obtained. The studies of scanning electron microscopy （SEM） show the surface etching ...The surface of polypropylene （iPP） is modified with glow discharge plasma of Ar, so that the modified surfaces of iPP films are obtained. The studies of scanning electron microscopy （SEM） show the surface etching pattern of iPP films. The chemical structures of iPP films are confirmed by X-ray photoelectron spectroscopy （XPS） and Fourier transform infrared （FTIR） spectroscopy. The wetting properties of modified surfaces of iPP films are characterized by contact angle, and the free energy of surfaces is calculated. The free radical of modification surfaces of iPP is measured by chemical method. The surfaces of iPP are achieved with Ar plasma treatment followed by grafting copolymerization with styrene （St） in St. The grafting polymer of St onto iPP is characterized by FTIR. The grafting rate is dependent on plasma exposure time and discharge voltage. The studies show that homopolymerization of St is undergone at the sane time during the graftingcopolymerization of St onto/PP.展开更多
The monomer methacrylamido propyl trimethy ammonium chloride( MAPTAC) was copolymerized onto the fiber surface of polypropylene( PP) nonwoven fabric under ultroviole radiation. The weak acid red GN dye adsorption and ...The monomer methacrylamido propyl trimethy ammonium chloride( MAPTAC) was copolymerized onto the fiber surface of polypropylene( PP) nonwoven fabric under ultroviole radiation. The weak acid red GN dye adsorption and adsorptive filtration performance of the resulted PP fabrics were investigated.The results showed that the grafting copolymerization preferred to happen in the inner layer of the fabrics. The water flux of the grafted fabrics decreases with the increase of grafting yield. The collapse of the grafted polymer chains causes the flux increase in acidic condition,or vice versa at alkaline version. The coiling of the polyelectrolyte chains upon the dye adsorption seems to violate the routine assumption of the rigid substrate, and this gets the adsorption energy constant negative. The static adsorption process follows the Lagergren's pseudo-second order kinetic equation. The removals of circa( ca.) 100% of the total permeation volume3 500 mL simulated dye wastewater was reached during permeation.The dye adsorbed fabrics were regenerated by the mixed media of the cationic surfactant / ethanol /water. The grafted fabric assumes stable fabric integrity and stability during permeation,and presents excellent dye adsorption capacity,easy desorption, and repeatable utilization.展开更多
[Objective] The paper was to study the structure and performance of starch and styrene graft copolymer. [Method] The microscopic structure of corn starch and styrene graft copolymer was analyzed by using infrared spec...[Objective] The paper was to study the structure and performance of starch and styrene graft copolymer. [Method] The microscopic structure of corn starch and styrene graft copolymer was analyzed by using infrared spectrum and scanning electron microscope, and the property of starch and styrene graft copoly- mer was confirmed through grinding experiment, tensile strength, water absorption rate, hot water resistance properties and enzymatic properties analysis. [Result] The starch and styrene graft copolymer had the properties of thermoplastic and microbial degradation. IConclusion] The starch and styrene graft copolymer is expected to be developed as a biodegradable material.展开更多
The copolymers were formed by the graft copolymerization of PVC with acrylic rare earth. The principle and method of the graft copolymerization of PVC and acrylic rare earth were discussed. The graft copolymers were c...The copolymers were formed by the graft copolymerization of PVC with acrylic rare earth. The principle and method of the graft copolymerization of PVC and acrylic rare earth were discussed. The graft copolymers were characterized by FT-IR spectra and scanning electron microscope (SEM).The thermal stability of the graft-copolymers was studied by thermogravimetric analysis (TG). The experiment results show that the thermal resistance and toughness of the graft copolymers are obviously enhanced.展开更多
The copolymerization of 4-vinylbenzyl chloride （VBC） and vinyl acetate （VAC） was carried out in toluene at 75℃ via radical polymerization using 2,2＇-azo-bis-（isobutyronitrile） （AIBN） as an initiator. The ran...The copolymerization of 4-vinylbenzyl chloride （VBC） and vinyl acetate （VAC） was carried out in toluene at 75℃ via radical polymerization using 2,2＇-azo-bis-（isobutyronitrile） （AIBN） as an initiator. The random copolymers of poly（4-vinylbenzyl chloride-co-vinyl acetate） （P（VBC-co-VAC）） with number average molecular weight （Mn） from 2000 to 6900, relatively narrow molecular weight distribution （MWD, Mw/Mn ca. 2.0） and with different copolymer composition of 4-vinylbenzyl chloride （VBC） from 17 mol% to 62 mol% could be obtained. The P（VBC-co-VAC） copolymers with an average number of 7 to 13 initiating sites of benzyl chloride per macromolecule could be used for the cationic polymerization of isobutylene （IB）. The cationic polymerizations of IB were further conducted by using P（VBC-co-VAC） copolymers as macroinitiators in conjunction with TICl4 at -40℃ in CH2Cl2. The effects of VBC/TiCl4 （molar ratio） on monomer conversion, Mn and MWD of the resultant copolymers were investigated under 3 sets of conditions. It is found that P（VBC-co-VAC）-g-PIB copolymers with relatively narrow MWD （Mw/Mn ca. 2.0） and with terminal tert-chlorine functional groups in branched PIB chains could be successfully synthesized when VBC/TiCl4 （molar ratio） was set in the range from 0.10 to 1.12. The unimodal GPC curve of the P（VBC-co-VAC）-g-PIB copolymers by RI detector was almost in harmony with the GPC curve by UV detector. The TEM image of the P（VBC-co-VAC）-g-PIB copolymer stained by RuO indicated that the copolymer formed a two-phase morphology with P（VBC-co-VAC）-rich domains of 20-100 um in size tethered by PIB branch segments.展开更多
A graft copolymer of polyacrylonitrile （PAN） with sodium salt of partially carboxymethylated tamarind kernel powder （Na-PCMTKP, DS ^-= 0.15） was synthesized by using ceric ammonium nitrate （CAN） as a redox initi...A graft copolymer of polyacrylonitrile （PAN） with sodium salt of partially carboxymethylated tamarind kernel powder （Na-PCMTKP, DS ^-= 0.15） was synthesized by using ceric ammonium nitrate （CAN） as a redox initiator in an aqueous medium. The optimum reaction conditions for affording maximum percentage of grafting were established by successively varying reaction conditions such as concentrations of nitric acid, CAN, monomer （AN） as well as reaction time, temperature and amount of substrate. The influence of these reaction conditions on the grafting yields was discussed. The kinetic scheme of free radical graft copolymerization was proposed and the experimental results were found to agree very well with the proposed kinetic scheme. The graft copolymer （Na-PCMTKP-g-PAN, percentage of grafting G = 413.76% and percentage of grafting efficiency GE = 96.48%） sample synthesized under the established optimized reaction conditions was hydrolyzed by 0.7 mol-L l NaOH solution at 90-95 ℃ to yield the superabsorbent hydrogel, H-Na-PCMTKP-g-PAN. The swelling behavior of the hydrogel was studied by carrying out its absorbency measurements in low conductivity water, 0.15 mol·L^-1 salt （NaCl, CaCl2 and AlCl3） solutions and simulated urine （SU） solution at different timings. FTIR, TGA and SEM techniques were used to characterize the products.展开更多
文摘In this paper, the capabilities of grafting acrylonitrile (AN) onto starch initiated by Fe(III)-TU, V(V)-TU, Cr(VI)-TU, Mn(VII)-TU redox systems were compared in the presence of sulfuric acid of different concentrations. It was shown that the grafting capability of Mn(VII)-TU is the highest in these initiating systems. Using Mn (VII-TU as initiator, the effects of various acids (HClO4, H2SO4, HNO3, HCl) on the graft copolymerization of acrylonitrile onto starch were discussed, and the capabilities of graft copolymerization of methyl methacrylate (MMA), acrylamide (AM), acrylic acid (AA) onto starch were investigated. The experimental results show that the order of the influences of different acids is HClO4 > H2SO4 > HNO3 > HCl, and the order of grafting capabilities of different monomers grafted onto starch is MMA > AN > AM > AA. The structure and morphology of graft, copolymers were studied with infrared spectroscopy and scanning electron microscopy. The size, shape and roughness of surface of the grafted starch granules are changed after grafting.
文摘With potassium persulfate (KPS) as initiator, graft copolymerization of ethyl acrylate (EA) onto water-soluble hydroxypropyl methylcellulose (HPMC) was investigated in aqueous medium. Effects of monomer concentration, initiator concentration, matrix concentration, and reaction temperature on the percentage of grafting (G) and grafting efficiency (G_E) were studied. The results show that G and G_E values both increase with the the increase of EA concentration and KPS concentration; when raising HPMC concentration from 0.12 mmol/L to 0.47 mmol/L, G decreases, while G_E increases;and when raising reaction temperature from 50 ℃ to 65 ℃,G increases, but G_E decreases. In addition, the graft copolymers were characterized by Fourier transform infrared (FTIR) spectra and transmission electron microscopy (TEM) methods.
基金the National Natural Science Foundation of China (No.50673071).
文摘2,2,3,3,4,4,5,5-Octafluoropentyl acrylate was grafted onto silk fiber in a two-step heterogeneous system through the vinyl bonds of acryloyloxyethyl isocyanate modified on the silk.The grafted copolylner was analyzed by FTIR and WAXD,and the results revealed that the fluoroacrylate was successfully grafted onto silk fiber and the crystalline structure of silk fibroin withβ-sheet structure was not changed after graft copolymerization.The FT-IR corrected method was used to simulate the grafting yield onto sil...
基金supported by the 11th Five-Year Plan of the National Scientific and Technological Support Projects of China (Grant No. 2006BAD18B10)the Major Project of Chinese National Programs for Fundamental Research and Development (973 Program) (Grant No. 2010CB732204)
文摘Dissolution and homogeneous graft copolymerization of cellulose were performed in an ionic liquid 1-allyl-3-methylimidazolium chloride （AmimCl） with 2-hydroxyethyl methacrylate. The synthesized AmimCl and cellulose graft copolymers were characterized by FTIR, ^1 H-NMR and XRD spectroscopy. The results show that AmimCl dissolved cellulose directly by destroying intermolecular and intramolecular hydrogen bonds in cellulose and the crystalline form of cellulose was transformed from cellulose Ⅰ to cellulose Ⅱ after regeneration from AmimCl. The best synthetic condition of the cellulose-graft-P （2-hydroxyethyl methacrylate） was that cellulose 0.5 g, 2-hydroxyethyl methacrylate 3.00 g and initiator ammonium persulfate 0.05 g reacted for 180 min at 60℃; the rate of grafting reached 77.3%.
文摘The effects of magnetic field on the graft ratio and stereoregularity of grafts of PVA-g-MMA in the presence ofbenzophenone during UV irradiation are discussed. By means of IR, it was found that the graft ratio was increased with the increment of magnetic field strength. Furthermore, application of relative weak magnetic field of 0.4 Tesla had been shown to substantially enhance the stereo-regularity of graft copolymer. The maximum stereo-regularity appeared when the graft ratio approached to 85% with the magnetic field of 1.2 Tesla (T). The resistance to moisture and heat resistance of the grafted copolymer in the presence of magnetic field were also improved.
文摘To enhance the polarization of starch, the oxidized starch-BA-MAA-Gd copolymer was synthesized by radical graft copolymerization. The structure of the graft copolymer was determined by IR, scanning electron microscopy, state thermal analysis and X-ray diffraction. The electrorheological properties of the graft copolymer were also investigated. The results show that shear stress increases with the increase of the graft copolymer loadings and the electric field intensity.
文摘K2 S2 O8 and rare earths （RE） were used as initiators to prepare superabsorbents by graft copolymerization of acrylic acid （ AA ） onto corn starch. The effects of monomer concentration, initiator K2 S2 O8 concentration, cross-linker concentration, reaction temperature and the concentration ratio of RE and K2 S2O8 on the graft copolymerization were studied in terms of the water absorption capacity of superabsorbents. Results indicate that the optimum conditions obtained for the grafting of AA onto 5g starch are as follows： AA of 75. 773 g/L, K2S20s of 0. 437 g/L, RE of 0. 874 g/L, cross-linker of 0. 381 g/L and temperature of 70 ℃. The maximum water absorption capacity obtained is 740 g/g. The new method of graft polymerization is easily proceeded and controlled. The graft copolymers were characterized by infra-red spectroscopy, scanning electron microscopy and TG. Results characterized by IR and SEM give strong evidence for grafting of AA onto corn starch, and those characterized by TG reveal that the grafting of AA improves the theimostability of corn starch.
文摘Natural rubber(NR)grafted with 2-ethylhexyl acrylate(2-EHA)and methacrylic acid(MAA,collectively NR-g-PEHA/MAA)was synthesized by emulsion polymerization.Tetraethylenepentamine and cumene hydroperoxide were used as redox initiators.The successful grafting of 2-EHA and MAA onto NR was confirmed by Fourier transform infrared spectroscopy.The morphology of the NR latex particles was observed by transmission electron microscopy.The effects of reaction temperature,initiator dosage,feeding mode,and hard monomer content on the mechanical properties of the modified NR film were investigated.Grafted polymer chains were unevenly wrapped on the outside of NR particles,and smaller particles were more easily grafted.Crosslinking was characterized using a toluene swelling method.Thermal stability and glass transition temperature were examined by differential scanning calorimetry and thermogravimetric analysis.The results showed that the thermal stability of NR-g-PEHA/MAA had been improved,and the glass transition temperature(Tg)was unchanged.
文摘Grafting copolymerizations of methyl acrylate(MA) and ethyl acrylate(EA) onto corn starch, respectively, initiated by potassium persulfate-sodium thiosulphate (KPS-STS) redox system, were studied. The structures of poly(MA)-g-starch and poly(EA)-g-starch were characterized by IR, SEM and X-ray diffraction. Experimental results show that KPS-STS is an efficient initiation system for grafting of MA and EA onto corn starch. The maximum percent grafting was obtained at [KPS] of 6.0× 10~3 mol/L, [STS] of 1.8× 10 5 mol/L, [M] of 6. 0× 101 mol/L, S:L=4:100 at 40℃ for 6 h. The reactivity order is MA>EA.
文摘The graft copolymerization of acrylonitrile (AN) onto starch under the initiation of potassium permanganate was investigated. The effect of various reaction conditions on the graft copolymerization was studied. The relationships between the grafting rate and the initiator concentration of potassium permanganate, monomer acrylonitrile and backbone starch, as well as reaction temperature were established. The oxidation reaction of starch with manganic ions and valence changes of manganic ions during the graft copolymerization were discussed. The results show that manganic ion Mn 7+ underwent a series of valence changes during the graft copolymerization: Mn(Ⅶ) → Mn(Ⅳ) → Mn(Ⅲ) → Mn(Ⅱ). The grafting rate of the graft copolymerization of acrylonitrile onto starch is also given.
文摘The starch/D,L-lactide graft copolymers were synthesized by reacting D,L-lactide with corn starch in N,N-dimethylacetamide (DMAM) in the presence of triethylamine (NEt3) and anhydrous lithium chloride. The effect of reaction time and the molar ratio of D,L-lactide to glucose structural unit of starch on monomer conversion(C%), graft (G%) and graft efficiency (GE%) were studied. The C%, G% and GE% could approach 37.3%,179.7% and 68.0%, respectively when the molar ratio of D,L-lactide to glucose structural unit of starch is 10:1 and the graft copolymerization was carried out at 80-85℃ for 4 hours under nitrogen atmosphere. The Fourier transforms infra-red (FTIR) spectroscopy, differential scanning calorimetry (DSC) and X-ray diffraction (XRD) spectroscopy were used in order to characterize the graft copolymers. FTIR spectra show that absorption band at 1740 cm-1 confirmed the formation of ester bond, indicating the starch /D,L-lactide graft copolymers were produced, the DSC characteristic results show the melting temperature of the graft copolymer were elevated slightly as the molar ratio of D,L-lactide to glucose structural units of starch increased and the X-ray diffraction spectra show the synthesized graft copolymers were amorphous. The degradability of graft copolymer was tested with the aid of acid, alkali and microbe such as bacillus subtilis and staphylococcus aureus. The results of water resistance show the graft copolymer produced can be used as a component of impermeable coating for cardboard.
文摘The graft copolymerization of acrylic acid (AA) with unswollen and swollen ramie fibers using chromic acid (H 2CrO 4) as the initiator has been studied in the presence of air. The effects of initiator concentration, monomer concentration, perchloric acid (HClO 4) concentration, time of polymerization, reaction temperature, and amount of ramie fibers on the graft percentage have been found out. The graft copolymer was characterized by IR spectra, scanning electron microscopy(SEM), differential thermal analysis (DTA), and thermogravimertric analysis (TGA).
基金financially supported by the National Natural Science Foundation of China (No.51473113)the Natural Science Foundation of Tianjin (No.12JCYBJC11900)
文摘Pentaerythritol triacrylate （PETA） was successfully grafted onto the plasma-treated isotactic polypropylene （iPP） via the in situ melt processing. The X-ray photoelectron spectroscopy （XPS） results showed that the hydroxyl and carbonyl groups, and peroxides could be generated via plasma treatment. The content of free radical in plasma-treated iPP （PiPP） was measured by 2,2-diphenyl-1- picrylhydrazyl （DPPH）. It was found that the resulting peroxides induced the grafting copolymerization of PETA onto iPP, and the grafted PETA promoted the formation of β-crystal in PiPP, which was evidenced by Fourier transform infrared spectroscopy （FTIR）, differential scanning calorimetry （DSC） and wide-angle X-ray diffraction （WAXD） measurements, respectively.
文摘Thermosensitive core-shell particles were synthesized through graft copolymerization of N-isopropylacrylamide with[3-(methacryloxy)propyl]trimethoxysilane(MPT)coupled on the surface of ultrafine silica beads.The copolymerization was carried out using polyvinyl alcohol as a surfactant,water and cyclohexanol as mixed solvent,and 2,29-azobis(isobutyronitrile)as an initiator.The effect of surfactant concentration and the composition of the mixed solvent on the graft rate were investigated.The structure of modified silica was confirmed by infrared spectra.Differential scanning calorimetry(DSC)has revealed the thermosensitivity of the particles.The thermosensitive particles were used as packing materials of high performance liquid chromatography(HPLC)columns for separating naphthalene derivatives.Satisfactory separation was obtained by controlling the temperature of the column.In contrast,the packing material of silica-MPT has no such separation efficiency due to the lack of thermosensitivity.The effect of the composition of the mobile phase on the separating efficiency was also investigated.The temperature-controlled separation was effective only when the water content was higher than 90%(v/v)in the water-methanol mobile phase.The mechanism for the temperature-controlled separation is attributed to a polarity change of poly(N-isopropylacrylamide)which undergoes volume phase transition on the silica surface as the temperature increases.
基金financially supported by the National Natural Science Foundation of China(No.50673073)the Doctoral Foundation of Ministry of Education of China(No.20060056043)
文摘The surface of polypropylene （iPP） is modified with glow discharge plasma of Ar, so that the modified surfaces of iPP films are obtained. The studies of scanning electron microscopy （SEM） show the surface etching pattern of iPP films. The chemical structures of iPP films are confirmed by X-ray photoelectron spectroscopy （XPS） and Fourier transform infrared （FTIR） spectroscopy. The wetting properties of modified surfaces of iPP films are characterized by contact angle, and the free energy of surfaces is calculated. The free radical of modification surfaces of iPP is measured by chemical method. The surfaces of iPP are achieved with Ar plasma treatment followed by grafting copolymerization with styrene （St） in St. The grafting polymer of St onto iPP is characterized by FTIR. The grafting rate is dependent on plasma exposure time and discharge voltage. The studies show that homopolymerization of St is undergone at the sane time during the graftingcopolymerization of St onto/PP.
基金the Priority Academic Development Program for Textile Science and Textile Engineering of Jiangsu Higher Education Institutions,Chinathe Environmental Protection Department of Jiangsu Province,China(No.2012009)Suzhou Municipal Government,China(No.SYG201202)
文摘The monomer methacrylamido propyl trimethy ammonium chloride( MAPTAC) was copolymerized onto the fiber surface of polypropylene( PP) nonwoven fabric under ultroviole radiation. The weak acid red GN dye adsorption and adsorptive filtration performance of the resulted PP fabrics were investigated.The results showed that the grafting copolymerization preferred to happen in the inner layer of the fabrics. The water flux of the grafted fabrics decreases with the increase of grafting yield. The collapse of the grafted polymer chains causes the flux increase in acidic condition,or vice versa at alkaline version. The coiling of the polyelectrolyte chains upon the dye adsorption seems to violate the routine assumption of the rigid substrate, and this gets the adsorption energy constant negative. The static adsorption process follows the Lagergren's pseudo-second order kinetic equation. The removals of circa( ca.) 100% of the total permeation volume3 500 mL simulated dye wastewater was reached during permeation.The dye adsorbed fabrics were regenerated by the mixed media of the cationic surfactant / ethanol /water. The grafted fabric assumes stable fabric integrity and stability during permeation,and presents excellent dye adsorption capacity,easy desorption, and repeatable utilization.
文摘[Objective] The paper was to study the structure and performance of starch and styrene graft copolymer. [Method] The microscopic structure of corn starch and styrene graft copolymer was analyzed by using infrared spectrum and scanning electron microscope, and the property of starch and styrene graft copoly- mer was confirmed through grinding experiment, tensile strength, water absorption rate, hot water resistance properties and enzymatic properties analysis. [Result] The starch and styrene graft copolymer had the properties of thermoplastic and microbial degradation. IConclusion] The starch and styrene graft copolymer is expected to be developed as a biodegradable material.
文摘The copolymers were formed by the graft copolymerization of PVC with acrylic rare earth. The principle and method of the graft copolymerization of PVC and acrylic rare earth were discussed. The graft copolymers were characterized by FT-IR spectra and scanning electron microscope (SEM).The thermal stability of the graft-copolymers was studied by thermogravimetric analysis (TG). The experiment results show that the thermal resistance and toughness of the graft copolymers are obviously enhanced.
基金supported by the National Natural Science Foundation of China(Nos.20774008,20934001)Program for Changjiang Scholars and Innovative Research Team in Universities(IRT0706)
文摘The copolymerization of 4-vinylbenzyl chloride （VBC） and vinyl acetate （VAC） was carried out in toluene at 75℃ via radical polymerization using 2,2＇-azo-bis-（isobutyronitrile） （AIBN） as an initiator. The random copolymers of poly（4-vinylbenzyl chloride-co-vinyl acetate） （P（VBC-co-VAC）） with number average molecular weight （Mn） from 2000 to 6900, relatively narrow molecular weight distribution （MWD, Mw/Mn ca. 2.0） and with different copolymer composition of 4-vinylbenzyl chloride （VBC） from 17 mol% to 62 mol% could be obtained. The P（VBC-co-VAC） copolymers with an average number of 7 to 13 initiating sites of benzyl chloride per macromolecule could be used for the cationic polymerization of isobutylene （IB）. The cationic polymerizations of IB were further conducted by using P（VBC-co-VAC） copolymers as macroinitiators in conjunction with TICl4 at -40℃ in CH2Cl2. The effects of VBC/TiCl4 （molar ratio） on monomer conversion, Mn and MWD of the resultant copolymers were investigated under 3 sets of conditions. It is found that P（VBC-co-VAC）-g-PIB copolymers with relatively narrow MWD （Mw/Mn ca. 2.0） and with terminal tert-chlorine functional groups in branched PIB chains could be successfully synthesized when VBC/TiCl4 （molar ratio） was set in the range from 0.10 to 1.12. The unimodal GPC curve of the P（VBC-co-VAC）-g-PIB copolymers by RI detector was almost in harmony with the GPC curve by UV detector. The TEM image of the P（VBC-co-VAC）-g-PIB copolymer stained by RuO indicated that the copolymer formed a two-phase morphology with P（VBC-co-VAC）-rich domains of 20-100 um in size tethered by PIB branch segments.
文摘A graft copolymer of polyacrylonitrile （PAN） with sodium salt of partially carboxymethylated tamarind kernel powder （Na-PCMTKP, DS ^-= 0.15） was synthesized by using ceric ammonium nitrate （CAN） as a redox initiator in an aqueous medium. The optimum reaction conditions for affording maximum percentage of grafting were established by successively varying reaction conditions such as concentrations of nitric acid, CAN, monomer （AN） as well as reaction time, temperature and amount of substrate. The influence of these reaction conditions on the grafting yields was discussed. The kinetic scheme of free radical graft copolymerization was proposed and the experimental results were found to agree very well with the proposed kinetic scheme. The graft copolymer （Na-PCMTKP-g-PAN, percentage of grafting G = 413.76% and percentage of grafting efficiency GE = 96.48%） sample synthesized under the established optimized reaction conditions was hydrolyzed by 0.7 mol-L l NaOH solution at 90-95 ℃ to yield the superabsorbent hydrogel, H-Na-PCMTKP-g-PAN. The swelling behavior of the hydrogel was studied by carrying out its absorbency measurements in low conductivity water, 0.15 mol·L^-1 salt （NaCl, CaCl2 and AlCl3） solutions and simulated urine （SU） solution at different timings. FTIR, TGA and SEM techniques were used to characterize the products.
