Ultraviolet （UV）-induced graft copolymerization of allyl acetate （AA） monomer onto poly（ethylene terephthalate） （PET） films and the subsequent sulfonation on the monomer units in the grafting chain using chlor...Ultraviolet （UV）-induced graft copolymerization of allyl acetate （AA） monomer onto poly（ethylene terephthalate） （PET） films and the subsequent sulfonation on the monomer units in the grafting chain using chlorosulfonic acid （C1SO3H） were carried out to prepare proton exchange membranes （PEMs） for fuel cells. A maximum grafting value of 12.8% was found for 35 vol% allyl acetate after 3 h radiation time. Optimum concentration of C1SO3H was selected for the sulfonation reaction to be 0.05 mol/L based on the degree of sulfonation and the tensile strength studies of the membrane. The degree of sulfonation increased as the sulfonation reaction temperature and sulfonation time were increasing. The radiation grafting and the sulfonation have been confirmed by titrimetric and gravimetric analyses as well as FTIR spectroscopy. The maximum ion exchange capacity （IEC） of 0.04125 mmol g-1 was found at 12.1% degree of sulfonation and the maximum proton conductivity was found to be 0.035 S cm-1 at 30℃ and a relative humidity of 60%. The various physical and chemical properties of the PEMs such as water uptake, mechanical strength, thermal durability and oxidative stability were also studied. To investigate the suitability of the prepared membrane for fuel cell applications, its properties were compared with those ofNafion 117.展开更多
This research work blooms the new idea of developing a safe and controlled drug releasing matrix using multi-walled carbon nanotubes(MWCNTs).In aqueous solution,uniform and highly stable dispersion of MWCNTs was obtai...This research work blooms the new idea of developing a safe and controlled drug releasing matrix using multi-walled carbon nanotubes(MWCNTs).In aqueous solution,uniform and highly stable dispersion of MWCNTs was obtained after secondary functionalization with polyethylene glycol(PEG)which was studied by Fourier transmission infrared spectroscopy(FTIR)and thermogravimetric analysis(TGA).Solution casting method was used to prepare MWCNTs/gelatin-chitosan nanocomposite films and the effect of MWCNTs on physico-mechanical,thermal and water uptake properties of the nanocomposites were evaluated.Incorporation of MWCNTs into the porous gelatin-chitosan matrix showed interesting stiffness and dampness along with developed microfibrillar structures within the pore walls intended at being used in tissue engineering of bone or cartilage.A common antibiotic drug,ciprofloxacin was incorporated into nanocomposite matrix.The evaluation of the effect of MWCNTs on drug release rate by dissolution test and antimicrobial susceptibility test was performed.Sharp release of the drug was found at early stages(~1 h),but the rate was reduced afterwards,showing a sustained release.It was observed that for all microorganisms,the antibacterial activities of drug loaded MWCNTs/gelatin-chitosan nanocomposites were higher than that of drug loaded gelatin-chitosan composite films containing no MWCNTs.Comparative statistical studies by ANOVA techniques also showed remarkable difference between the antibacterial activities,exhibited by MWCNTs-incorporated and non-incorporated composite films.展开更多
文摘Ultraviolet （UV）-induced graft copolymerization of allyl acetate （AA） monomer onto poly（ethylene terephthalate） （PET） films and the subsequent sulfonation on the monomer units in the grafting chain using chlorosulfonic acid （C1SO3H） were carried out to prepare proton exchange membranes （PEMs） for fuel cells. A maximum grafting value of 12.8% was found for 35 vol% allyl acetate after 3 h radiation time. Optimum concentration of C1SO3H was selected for the sulfonation reaction to be 0.05 mol/L based on the degree of sulfonation and the tensile strength studies of the membrane. The degree of sulfonation increased as the sulfonation reaction temperature and sulfonation time were increasing. The radiation grafting and the sulfonation have been confirmed by titrimetric and gravimetric analyses as well as FTIR spectroscopy. The maximum ion exchange capacity （IEC） of 0.04125 mmol g-1 was found at 12.1% degree of sulfonation and the maximum proton conductivity was found to be 0.035 S cm-1 at 30℃ and a relative humidity of 60%. The various physical and chemical properties of the PEMs such as water uptake, mechanical strength, thermal durability and oxidative stability were also studied. To investigate the suitability of the prepared membrane for fuel cell applications, its properties were compared with those ofNafion 117.
文摘This research work blooms the new idea of developing a safe and controlled drug releasing matrix using multi-walled carbon nanotubes(MWCNTs).In aqueous solution,uniform and highly stable dispersion of MWCNTs was obtained after secondary functionalization with polyethylene glycol(PEG)which was studied by Fourier transmission infrared spectroscopy(FTIR)and thermogravimetric analysis(TGA).Solution casting method was used to prepare MWCNTs/gelatin-chitosan nanocomposite films and the effect of MWCNTs on physico-mechanical,thermal and water uptake properties of the nanocomposites were evaluated.Incorporation of MWCNTs into the porous gelatin-chitosan matrix showed interesting stiffness and dampness along with developed microfibrillar structures within the pore walls intended at being used in tissue engineering of bone or cartilage.A common antibiotic drug,ciprofloxacin was incorporated into nanocomposite matrix.The evaluation of the effect of MWCNTs on drug release rate by dissolution test and antimicrobial susceptibility test was performed.Sharp release of the drug was found at early stages(~1 h),but the rate was reduced afterwards,showing a sustained release.It was observed that for all microorganisms,the antibacterial activities of drug loaded MWCNTs/gelatin-chitosan nanocomposites were higher than that of drug loaded gelatin-chitosan composite films containing no MWCNTs.Comparative statistical studies by ANOVA techniques also showed remarkable difference between the antibacterial activities,exhibited by MWCNTs-incorporated and non-incorporated composite films.
