Electrospun polymers have many applications in the industry.However, the structure of these polymers has been less widely considered by researchers.In this work, the structural effect of electrospun and casted films o...Electrospun polymers have many applications in the industry.However, the structure of these polymers has been less widely considered by researchers.In this work, the structural effect of electrospun and casted films of polyacrylonitrile(PAN) and polyvinylidene fluoride(PVDF) polymers on water vapor transmission were investigated.Sorption of water vapor was measured at 35, 60 and 80 ℃ and different relative humidities.The diffusion coefficients were calculated based on mass changes of the polymer sample.The water vapor transmission rate(WVTR) was also measured at 35 ℃ and 90% relative humidity.The results indicated that electrospun nano-fibrous polymers(ESNPs) absorb much higher water vapor compared to non-porous casted polymers.The interaction of water molecules with mentioned polymers was investigated based on Flory-Huggins theory.The Flory-Huggins interaction parameter of electrospun films was less than casted films, suggesting much better interaction of water molecules with electrospun films.It was also found that electrospun films have anomalous kinetic behavior and do not obey the Fickian diffusion model.Finally, it was revealed that ESNPs show less resistance to water vapor transmission and they are good candidates for the applications of water vapor separation using membranes.展开更多
A comprehensive literature review was performed to create an inventory of thermal-physiological quantities for fabrics from different fiber materials, material blends, and fabric structures. The goal was to derive ove...A comprehensive literature review was performed to create an inventory of thermal-physiological quantities for fabrics from different fiber materials, material blends, and fabric structures. The goal was to derive over-arching concepts that cannot be seen by the individual studies alone. Equations of best fits suggest non-linear changes for fabric thickness, thermal and water-vapor resistance with changes in material blend ratio. Air permeability decreases with increasing fabric density and fabric weight wherein the degree of decrease differs among fabric materials, blend ratio, and fabric structure. Water-vapor transmission rates strongly depend on fabric thickness, material, and blend, but marginally depend on fabric structure as long as the fabric and material thickness remain the same.展开更多
文摘Electrospun polymers have many applications in the industry.However, the structure of these polymers has been less widely considered by researchers.In this work, the structural effect of electrospun and casted films of polyacrylonitrile(PAN) and polyvinylidene fluoride(PVDF) polymers on water vapor transmission were investigated.Sorption of water vapor was measured at 35, 60 and 80 ℃ and different relative humidities.The diffusion coefficients were calculated based on mass changes of the polymer sample.The water vapor transmission rate(WVTR) was also measured at 35 ℃ and 90% relative humidity.The results indicated that electrospun nano-fibrous polymers(ESNPs) absorb much higher water vapor compared to non-porous casted polymers.The interaction of water molecules with mentioned polymers was investigated based on Flory-Huggins theory.The Flory-Huggins interaction parameter of electrospun films was less than casted films, suggesting much better interaction of water molecules with electrospun films.It was also found that electrospun films have anomalous kinetic behavior and do not obey the Fickian diffusion model.Finally, it was revealed that ESNPs show less resistance to water vapor transmission and they are good candidates for the applications of water vapor separation using membranes.
文摘A comprehensive literature review was performed to create an inventory of thermal-physiological quantities for fabrics from different fiber materials, material blends, and fabric structures. The goal was to derive over-arching concepts that cannot be seen by the individual studies alone. Equations of best fits suggest non-linear changes for fabric thickness, thermal and water-vapor resistance with changes in material blend ratio. Air permeability decreases with increasing fabric density and fabric weight wherein the degree of decrease differs among fabric materials, blend ratio, and fabric structure. Water-vapor transmission rates strongly depend on fabric thickness, material, and blend, but marginally depend on fabric structure as long as the fabric and material thickness remain the same.
