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
When ethyl 3-fluoroalkyl-3-haloacrylate was treated with excess CH2N2,1-methyl-3-ethoxycarbonyl-4-fluoroalkylpyr azoles(3)and 1-methyl-5-ethoxycarbonyl-4-fluoroalkylpyrazoles(4)were obtained with a ratio of 90-95:10-5...When ethyl 3-fluoroalkyl-3-haloacrylate was treated with excess CH2N2,1-methyl-3-ethoxycarbonyl-4-fluoroalkylpyr azoles(3)and 1-methyl-5-ethoxycarbonyl-4-fluoroalkylpyrazoles(4)were obtained with a ratio of 90-95:10-5 in good yield.展开更多
Poly (EA-MAn-APTES)/silica hybrid materials were successfully prepared fromEthyl acrylate (EA), maleic anhydride (MAn) and tetraethoxysilane (TEOS) in the presence of acoupling agent 3-aminopropyltriethoxysilane (APTE...Poly (EA-MAn-APTES)/silica hybrid materials were successfully prepared fromEthyl acrylate (EA), maleic anhydride (MAn) and tetraethoxysilane (TEOS) in the presence of acoupling agent 3-aminopropyltriethoxysilane (APTES),by free-radical solution polymerization and insitu sol-gel process. The mass fraction of TEOS varied from 0 to 25%. The hybrid materials werecharacterized by the methods of FT-IR spectra, solvent extraction, scanning electron microscope (SEM), transmission electron microscope (TEM), differential scanning calorimetry (DSC) andthermogravimetric analysis (TGA) measuring apparatus to get their structures, gel contents,morphologies, particle sizes and thermal performances. The results show that the covalent bonds arebetween organic and inorganic phases, gel contents in the hybrid materials are much higher, theSiO_2 phase is well dispersed in the polymer matrix, silicon dioxide exist at nanoscale in thecomposites and have excellent thermal stability.展开更多
A series of acrylonitrile (AN) copolymers with methyl acrylate (MA) or ethyl acrylate (EA) as comonomer (5-23 wt%) was prepared by free-radical copolymerisation. The permeability coefficients of the copolymers to oxyg...A series of acrylonitrile (AN) copolymers with methyl acrylate (MA) or ethyl acrylate (EA) as comonomer (5-23 wt%) was prepared by free-radical copolymerisation. The permeability coefficients of the copolymers to oxygen and carbon dioxide were measured at 1.0 MPa and at 30 degrees C, and those to water vapor also measured at 100% relative humidity and at 30 degrees C. All the AN/acrylic copolymers are semicrystalline. As the acrylate content increase, the permeability coefficients of the copolymers to oxygen and carbon dioxide are increased progressively, but those to water vapor are decreased progressively. The gas permeability coefficients of the polymers were correlated with free-volume fractions or the ratio of free volume to cohesive energy.展开更多
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.
文摘When ethyl 3-fluoroalkyl-3-haloacrylate was treated with excess CH2N2,1-methyl-3-ethoxycarbonyl-4-fluoroalkylpyr azoles(3)and 1-methyl-5-ethoxycarbonyl-4-fluoroalkylpyrazoles(4)were obtained with a ratio of 90-95:10-5 in good yield.
文摘Poly (EA-MAn-APTES)/silica hybrid materials were successfully prepared fromEthyl acrylate (EA), maleic anhydride (MAn) and tetraethoxysilane (TEOS) in the presence of acoupling agent 3-aminopropyltriethoxysilane (APTES),by free-radical solution polymerization and insitu sol-gel process. The mass fraction of TEOS varied from 0 to 25%. The hybrid materials werecharacterized by the methods of FT-IR spectra, solvent extraction, scanning electron microscope (SEM), transmission electron microscope (TEM), differential scanning calorimetry (DSC) andthermogravimetric analysis (TGA) measuring apparatus to get their structures, gel contents,morphologies, particle sizes and thermal performances. The results show that the covalent bonds arebetween organic and inorganic phases, gel contents in the hybrid materials are much higher, theSiO_2 phase is well dispersed in the polymer matrix, silicon dioxide exist at nanoscale in thecomposites and have excellent thermal stability.
基金The project is supported by the National Natural Science Foundation of China
文摘A series of acrylonitrile (AN) copolymers with methyl acrylate (MA) or ethyl acrylate (EA) as comonomer (5-23 wt%) was prepared by free-radical copolymerisation. The permeability coefficients of the copolymers to oxygen and carbon dioxide were measured at 1.0 MPa and at 30 degrees C, and those to water vapor also measured at 100% relative humidity and at 30 degrees C. All the AN/acrylic copolymers are semicrystalline. As the acrylate content increase, the permeability coefficients of the copolymers to oxygen and carbon dioxide are increased progressively, but those to water vapor are decreased progressively. The gas permeability coefficients of the polymers were correlated with free-volume fractions or the ratio of free volume to cohesive energy.
