RESUMO
ConspectusSince the discovery of polymers of intrinsic microporosity (PIMs) in 2004, the fast size-selective interconnected pore cavities of the polymers have caused the upper bound of membrane performance to be revised, twice. Simultaneously, porous materials have meant that mixed matrix membranes (MMMs) are now a relatively simple method of enhancing transport properties. While there are now reliable routes with mixed matrices to improve the fundamental transport properties of membrane materials, many of the other properties crucial for separation applications remain largely unaddressed. Physical aging severely affects membrane performance over time, especially for those prepared from high fractional free volume polymers. Gradual densification of the glassy polymer chains causes the connected pore channels present in these materials to constrict. Studies now suggest that aging of superglassy polymer materials is a two-step process; a rapid densification occurs within the first few days, followed by a gradual rearrangement of packed chains over longer time frames toward a theoretical equilibrium state. Although advantageous in terms of size selectivity, the considerable drop in permeation over the days and weeks after manufacture greatly impacts material applicability. While often still permeating faster than traditional membrane materials, the continuous gradual collapse of cavities in these polymers are a significant challenge in the application of high free volume polymer membranes. In 2014, we discovered that the porous aromatic framework PAF-1 not only greatly improved the membrane's void space and speed of gas transport but also seemingly froze several glassy polymers in a low-density state, holding the polymer's pore channels open, a process termed as Porosity Induced Side chain Adsorption (PISA).This discovery of PISA fundamentally challenged the conventional wisdom at the time that the aging rate could only be addressed by densification of the polymer. Unlike other high-performance glassy polymers, membranes containing PAF-1 can retain their high permeability for more than a year. Several other examples of antiaging behavior have been subsequently reported by the team, where control of aging rate as a function of gas penetrant, selectivity increases, and stability at higher pressures was reported. These works also demonstrate that these mixed matrix systems had applicability for several other separations, including pervaporation, solvent nanofiltration, and as separators for energy applications. In our subsequent studies, the antiaging mechanism has been elucidated as an effect of the interaction between the polymer's accessible pendant methyl group and the aromatic pore surface of PAF-1 or other antiaging additives. In otherwise identical MMMs, where this hypothesized methyl-π interaction is either absent or interrupted, we find that the antiaging behavior expected by the fixation of the polymer chains to the pore surface and PAF-1 does not occur. As a design approach for mixed matrix membranes, targeted interfacial interactions are a promising pathway for developing other stable membranes, enabling the exciting class of PIM materials to improve industrial separation efficiency.
RESUMO
This paper examines the indirect effect of interpersonal and informational justice on organizational identification through psychological contract fulfillment across different levels of equity sensitivity. The data were collected using self-reported measures from 656 permanent employees working in five commercial banks in Pakistan. The statistical results of the study confirmed that the indirect effect of interpersonal and informational justice on organizational identification through psychological contract fulfillment is significant. However, the statistical results of the study also demonstrated that the indirect effect of interpersonal and informational justice does not differ across different levels of equity sensitivity. This study offers some implications for managers to maintain an effective employment relationship with the employees inside the organizations (AU)
Este artículo analiza el efecto indirecto de la justicia interpersonal e informativa en la identificación con la organización a través del cumplimiento del contrato psicológico en los diferentes niveles de sensibilidad a la equidad. Por medio de medidas de autoinforme se recogieron datos de 656 empleados fijos de cinco bancos comerciales de Paquistán. Los resultados estadísticos del estudio confirman que es significativo el efecto indirecto de la justicia interpersonal e informativa en la identificación con la organización a través del cumplimiento del contrato psicológico. No obstante, dichos resultados demuestran también que el efecto indirecto de la justicia interpersonal e informativa no es distinto en los distintos niveles de sensibilidad a la equidad. El estudio propone algunas implicaciones para que los directivos mantengan una relación eficaz de empleo con los empleados en el seno de las organizaciones (AU)
