Comparative study of the radiation-induced grafting of styrene onto poly(tetrafluoroethylene-co-perfluoropropylvinyl ether) and polypropylene substrates. I: Kinetics and structural investigation

A comparative study has been made of the radiation grafting of styrene onto poly(tetrafluoroethylene-co-perfluoropropyl vinyl ether) (PFA) and polypropylene (PP) substrates, using the simultaneous irradiation method. Effects of grafting conditions such as monomer concentrations, type of solvent, dose rate and irradiation dose on the grafting yield were investigated. Under the same grafting conditions it was found that a higher degree of grafting of styrene was obtained using a mixture of dichloromethane/methanol solvents for PFA and methanol for PP and the degree of grafting was higher in PP than in PFA at all doses. However, the micro-Raman spectroscopy analysis of the graft revealed that, for the same degree of grafting, the penetration depth of the grafted polystyrene into the substrate was higher in PFA than in PP substrates. In both polymers the crystallinity was hardly affected by the grafting process and the degree of crystallinity decreased slightly with grafting dose. The dependence of the initial rate of grafting on the dose rate and the monomer concentration was found to be 0.6 and 1.4 order for PFA and 0.15 and 2.2 for PP, respectively. The degree of grafting increased with increasing radiation dose in both polymers. However, the grafting yield decreased with an increase in the dose rate. The increase in the overall grafting yield for PFA and PP was accompanied by a proportional increase in the penetration depth of the graft into the substrates. (C) 2003 Society of Chemical Industry.

A study of the radiation chemistry of poly(chlorotrifluoroethylene) by ESR spectroscopy

The ESR spectra of poly(chlorotrifluoroethylene) were recorded following gamma-radiolysis under vacuum at room temperature and 77 K. The very broad spectrum at 77 K revealed little fine structure with which to identity the radicals formed upon irradiation, but subsequent photobleaching and annealing studies, together with radiolytic studies at higher temperatures, afforded scope for making radical assignments. Both main-chain radicals and a range of chain-end radicals have been identified. The G-values for radical formation were 1.55, 0.36 and 0.32 at 77 K, 273 K and room temperature, respectively. (C) 2003 Elsevier Science Ltd. All rights reserved.

G-values for scission and crosslinking on γ-radiolysis of Ultem at 303 K

The radiation chemical yields G(S) and G(X) for H-linking and Y-linking models for Ultem have been calculated from molecular weight analysis by gel permeation chromatography. These G-values have been compared with the G-values obtained from analysis of soluble fractions above the gel dose, Which have been reported in previous works. An analysis of the molecular weight data in terms of H-linking and Y-linking mechanisms yielded values of G(S-H) = 1.0 x 10(-3) and G(H) = 6.0 x 10(-3) and G(S-Y) = 1.3 x 10(-2) and G(Y) = 1.8 x 10(-2). The corresponding values obtained from the solubility data were G(SH) = 0.53 x 10(-2), G(H) = 1.39 x 10(-2), G(S-Y) = 4.2 x 10(-2) and G(Y) - 4.6 x 10(-2). The origin of the disagreement between the molecular weight and solubility values is not clear, but it could arise as a result of observed microgel formation below the reported gel dose of 0.13 MGy. Whether the crosslink mechanism proceeds by an H-linking or Y-linking process is also unclear and will require direct observation of the crosslinking structures.

An investigation of the thermal and tensile properties of PFA following γ-radiolysis

For some applications for fluoropolymers they must be subjected to high-energy radiation, e.g., when they are grafted with styrene using an irradiation method to produce fuel cell membranes or matrix supports for combinatorial chemistry. In some of these applications they may be subjected to mechanical stress or elevated temperature, so it is important to elucidate the effects of the radiolysis on these properties. In the present work the effect of gamma-radiolysis on the glass transition, melting behavior, and thermal stability of PFA has been studied as well as the effect of the radiolysis on the tensile properties of the polymer.

Investigation of the vapor-phase grafting of styrene onto PFA

Poly(tetrafluoroethylene-co-perfluoropropyI vinyl ether), PFA, was grafted with styrene from the vapor phase using a simultaneous radiation grafting method. The graft yields were measured as a function of the dose and dose rate and were found to be initially linearly dependent on the dose and independent of the dose rate up to dose rates of similar to3 kGy/h. However, at a dose rate of 6.2 kGy/h, the slope of the yield-grafting time plot decreased. Raman depth profiles of the grafts showed that the polystyrene concentrations were greatest near the surface of the grafted samples and decreased with depth. The maximum penetration depth of the graft depended on the radiation dose for a fixed dose rate. Fmoc-Rink loading tests showed that the grafts displayed superior loading compared to grafts prepared from bulk styrene or from styrene solutions other than methanol.

Boletim eletr??nico de bibliografias especializadas: igualdade de g??nero

A 2?? edi????o de 2013 do Boletim Eletr??nico de Bibliografias Especializadas destaca o tema Igualdade de G??nero. O documento traz indica????es de pu-blica????es do acervo da Biblioteca Graciliano Ramos/ENAP com reflex??es acerca das desi-gualdades entre homens e mulheres e suas consequ??ncias ?? sociedade. O objetivo ?? dar publicidade a esses materiais, visando a con-tribuir para uma melhor compreens??o do com-plexo cen??rio de defini????o das prioridades p??blicas e da formula????o de pol??ticas p??blicas governamentais comprometidas com a pers-pectiva de g??nero, em seus diversos aspectos. De acordo com a Organiza????o das Na????es Unidas para a Educa????o, a Ci??ncia e a Cultura (Unesco), os direitos das mulheres devem ser entendidos como direitos humanos e cultu-rais fundamentais. J?? a Pol??tica Nacional para as Mulheres, coordenada pela Secre-taria Especial de Pol??ticas para as Mulhe-res (SPM), da Presid??ncia da Rep??blica, tem como pressupostos e princ??pios a equi-dade, a autonomia das mulheres, a laicida-de do Estado, a universalidade das pol??ti-cas, a justi??a social, a transpar??ncia dos atos p??blicos, a participa????o e o controle social.

G??nero, ra??a e espa??os de poder: o caso de Maria Ant??nia e Geraldo

O caso relata uma situa????o de promo????o em ??rg??o p??blico na qual dois funcion??rios ??? uma mulher negra e um homem branco - se mostram como candidatos ao cargo. S??o apresentados os perfis e habilidades profissionais dos dois servidores e, ao final, a decis??o tomada pelo Secret??rio, chefe de ambos. O estudo suscita discuss??es sobre pr??ticas discriminat??rias nos espa??os de poder das institui????es p??blicas e o papel do dirigente para combater ou difundir tais pr??ticas. Pode ser aplicado em cursos sobre lideran??a, gest??o de pessoas e ??tica e servi??o p??blico

Gentileza ou ass??dio: conflitos de g??nero e de ra??a nas rela????es de trabalho

Com o afastamento do chefe do setor por quest??es m??dicas, Carla, que j?? exercia eventualmente a chefia da equipe, tornou-se a substituta do cargo, s?? n??o contava com o ass??dio de Ricardo, funcion??rio querido por todos. As investidas foram ficando cada vez mais agressivas e Carla n??o sabia mais como lidar com a situa????o. Come??ou a ter problemas com a sua equipe e sofrer difama????es por parte de Ricardo. O cen??rio encontrado pelo chefe ao voltar da licen??a foi de uma equipe desestabilizada. O caso trata do tema de ass??dio moral, agregado ?? quest??o racial e de g??nero, e suscita discuss??o sobre como um dirigente deve atuar para evitar a pr??tica dos ass??dios moral e sexual na equipe que gerencia, bem como para remediar situa????es j?? consolidadas. Pode ser aplicado em cursos sobre lideran??a, gest??o de pessoas e ??tica e servi??o p??blico

H?? um g??nero mais adequado para determinada fun????o?

Carolina foi aprovada em concurso p??blico para cargo t??cnico de hidrot??cnico e assinou contrato de experi??ncia por 90 dias. Contudo, durante a realiza????o das atividades inerentes ao cargo, n??o recebeu nenhuma orienta????o do seu supervisor. No momento da avalia????o de desempenho, foi mal avaliada tanto pelo supervisor quanto por sua chefia, que desde o in??cio demonstrava que o cargo n??o era apropriado para mulheres. Por conta dessa avalia????o, Carolina buscou ajuda na Ouvidoria do ??rg??o, mas acabou sendo demitida. Optou, ent??o, por recorrer ?? Justi??a. O caso trata de situa????o na qual ?? colocada em xeque a quest??o de g??nero para determinada fun????o no servi??o p??blico. O estudo pode ser aplicado em cursos com enfoque em quest??es vinculadas ?? diversidade de g??nero, ??s posturas das chefias que lidam com avalia????o de desempenho, bem como ao papel da Ouvidoria

Projeto b??sico: oficina de avalia????o do Programa Estudante Conv??nio de Gradua????o -PEC-G

Contrata????o de servi??os t??cnicos profissionais especializados de modera????o de Oficina Sob Medida, objetivando a realiza????o de Oficina de Avalia????o

G??nero, ra??a e compet??ncias de dire????o no servi??o p??blico federal

O relat??rio, que teve sua publica????o apoiada pela Canad?? School of Public Service, apresenta os resultados de uma pesquisa sobre a dificuldade de acesso de mulheres e negros aos cargos superiores da administra????o p??blica federal, bem como os conhecimentos, habilidades e atitudes necess??rios para o desempenho de cargos de dire????o desses segmentos