Synthesis and characterization of novel graft copolymers by radiation induced grafting

The radiation-induced graft copolymerization of N-vinyl-2-pyrrolidone (NVP), 4-vinyl pyridine (4VP), 2-vinyl pyridine (2VP) monomers onto poly (ethylene-alt-tetrafluoroethylene) (ETFE) was investigated. The influence of synthesis conditions particularly the solvent was studied. Various solvents, such as n-propanol, isoproponol, benzyl alcohol, methanol, ethanol, cyclohexanone, tetrahydrofuran (THF), nitromethane, 1,4-dioxane and n-heptane were examined for this purpose. Graft copolymers were characterized by Fourier transform infrared (FTIR) spectroscopy, dynamic mechanical analysis (DMA), and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDAX). It was found that the nature of the solvent had profound influence over the grafting reaction. Cyclohexanone, n-propanol and isoproponol for 4VP/ETFE grafting, THF and 1,4-dioxane for NVP/ETFE grafting and benzyl alcohol and methanol for 2VP/ETFE grafting were found to be the suitable solvents yielding highest graft levels. Isoproponol and n-propanol are promising in terms of both graft level and mechanical properties for 4VP/ETFE. Grafting of NVP, 4VP and 2VP onto ETFE were verified through FTIR spectroscopy. Storage modulus and glass transition temperature of the copolymers were found to increase as graft level increased. Surface profile of representative films was also investigated by viewing the distribution of elemental nitrogen using SEM-EDAX. Results indicated that copolymers of 4VP, NVP and 2VP are considerably different from each other. 4VP based copolymers exhibited relatively more homogenous grafting over the surface compared to NVP and 2VP based copolymers

Design, characterization and modeling of high temperature proton exchange membranes in dead ended anode operated polymer electrolyte membrane fuel cell

Polymer electrolyte membrane fuel cells (PEMFC) have the potential to reduce our pollutant emissions and dependence on fossil fuels. Factors such as complex balance-of-plant design and cost still remain as the major barriers to fuel cell. The eradication of the two main shortcomings of PEMFC has been targeted in this thesis study. The first shortcoming is high cost of the membrane and its water depended low operation temperature. The second one is the complex balance-of-plant design of PEMFC system. The synthesized, radiation grafted, high temperature proton conducting membrane improves the operation temperature of conventional PEMFC (i.e., <80 °C) up to 120 °C. The novel, high temperature proton conducting membrane eliminates the electrochemical by product water and improves the overall performance of PEMFC. Moreover, the synthesized, high temperature proton conducting membrane is cost competitive and very well suited for bulk production in any defined size. The dead ended anode (DEA) operation is considered as an alternative to the conventional PEMFC system. The operation with a DEA reduces fuel cell system cost, weight, and volume since the anode external humidification and recirculation hardware can be eliminated. Thus, the conventional PEMFC system is modified according to DEA operation in the study. The shortcomings of the commercial membrane in the DEA operation have been reduced with the synthesized, high temperature proton exchange membrane. Additionally, a transient, one dimensional along the channel numerical model is developed. The model is used to understand the two phase water transport mechanism during a low temperature DEA operation

Synthesis and Characterization of Novel Graft Copolymers by Radiation Induced Grafting

ABSTRACT The radiation-induced graft copolymerization of N-vinyl-2-pyrrolidone (NVP), 4-vinyl pyridine (4VP), 2-vinyl pyridine (2VP) monomers onto poly (ethylene-alt-tetrafluoroethylene) (ETFE) was investigated. The influence of synthesis conditions particularly the solvent was studied. Various solvents, such as n-propanol, isoproponol, benzyl alcohol, methanol, ethanol, cyclohexanone, tetrahydrofuran (THF), nitromethane, 1,4-dioxane and n-heptane were examined for this purpose. Graft copolymers were characterized by Fourier transform infrared (FTIR) spectroscopy, dynamic mechanical analysis (DMA), and scanning electron microscopy-energy dispersive spectroscopy (SEM-EDAX). It was found that the nature of the solvent had profound influence over the grafting reaction. Cyclohexanone, n-propanol and isoproponol for 4VP/ETFE grafting, THF and 1,4-dioxane for NVP/ETFE grafting and benzyl alcohol and methanol for 2VP/ETFE grafting were found to be the suitable solvents yielding highest graft levels. Isoproponol and n-propanol are promising in terms of both graft level and mechanical properties for 4VP/ETFE. Grafting of NVP, 4VP and 2VP onto ETFE were verified through FTIR spectroscopy. Storage modulus and glass transition temperature of the copolymers were found to increase as graft level increased. Surface profile of representative films was also investigated by viewing the distribution of elemental nitrogen using SEM-EDAX. Results indicated that copolymers of 4VP, NVP and 2VP are considerably different from each other. 4VP based copolymers exhibited relatively more homogenous grafting over the surface compared to NVP and 2VP based copolymers