Evaporation kinetics in swollen porous polymeric networks

Ponencia presentada en el Congreso Euromar 2014.Fil: Velasco, Manuel Isaac. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Física Enrique Gaviola; Argentina.Fil: Silletta, Emilia Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Física Enrique Gaviola; Argentina.Fil: Monti, Gustavo Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Física Enrique Gaviola; Argentina.Fil: Acosta, Rodolfo Héctor. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Física Enrique Gaviola; Argentina.Fil: Velasco, Manuel Isaac. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Silletta, Emilia Victoria. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Monti, Gustavo Alberto. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Acosta, Rodolfo Héctor. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Gomez, Cesar Gerardo. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica; Argentina.Fil: Strumia, Miriam Cristina. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica; Argentina.Fil: Gomez, Cesar Gerardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Gomez, Cesar Gerardo. Universidad Nacional de Córdoba. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Strumia, Miriam Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Strumia, Miriam Cristina. Universidad Nacional de Córdoba. Instituto Multidisciplinario de Biología Vegetal; Argentina.Polymer matrices with well defined structure and pore sizes are widely used in several areas of chemistry such as catalysis, enzyme immobilization, HPLC, adsorbents or controlled drug release. These polymers have pores in its structure both in the dry and swollen state. Although it is well known that the structures and properties greatly differ between these two states, only few methods provide information about the swollen one, even though most of the applications involve the matrices in this situation. Nuclear Magnetic Resonance (NMR) is a suitable tool for the study of the molecular dynamics of different liquids spatially confined in macro, meso and nanopores, through changes in the relaxation times. In transverse relaxation experiments, either diffusion inside the pore, or relaxation induced by mobility restriction of the liquid near the wall, are additional sources of relaxation, which are extremely useful in the determination of structural and functional properties.Fil: Velasco, Manuel Isaac. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Física Enrique Gaviola; Argentina.Fil: Silletta, Emilia Victoria. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Física Enrique Gaviola; Argentina.Fil: Monti, Gustavo Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Física Enrique Gaviola; Argentina.Fil: Acosta, Rodolfo Héctor. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Física Enrique Gaviola; Argentina.Fil: Velasco, Manuel Isaac. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Silletta, Emilia Victoria. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Monti, Gustavo Alberto. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Acosta, Rodolfo Héctor. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Gomez, Cesar Gerardo. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica; Argentina.Fil: Strumia, Miriam Cristina. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Departamento de Química Orgánica; Argentina.Fil: Gomez, Cesar Gerardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Gomez, Cesar Gerardo. Universidad Nacional de Córdoba. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Strumia, Miriam Cristina. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto Multidisciplinario de Biología Vegetal; Argentina.Fil: Strumia, Miriam Cristina. Universidad Nacional de Córdoba. Instituto Multidisciplinario de Biología Vegetal; Argentina.Física de los Materiales Condensado

Effects of Porosity and Thermal Treatment on Hydration of Mushrooms

In this study, hydration of mushroom as a porous food material has been studied considering their biphasic character. It consists of a solid phase that consists of intertwined hyphae and having cell walls with a swellable polymeric matrix and a pore phase made up by the space in between the hyphae. We have investigated the hydration of mushrooms as a function of initial porosity and thermal treatment. Variation in porosity is induced by the natural variation in the growth of mushroom. Porosity is measured by the weight gain during vacuum infiltration of mushroom caps with the mushroom isotonic solution. The hydration of the heat-treated mushroom shows a linear increase with the porosity of mushroom. Storage of mushroom increases the porosity with the number of storage days, which has also been confirmed with X-ray tomography(XRT) measurements. Finally, we show that the hydration of thermal-treated mushroom has two independent contributions, from porosity and temperature of the heat treatment. Current theories deal only with the latter contribution to the hydration of foods and need to be extended for accounting porosity of the food.</p

Drying kinetics of deformable and cracking nano-porous gels

The desiccation of porous materials encompasses a wide range of technological and industrial processes and is acutely sensitive to the hierarchical structure of the porous materials resulting in complex dynamics which are challenging to unravel. Macroscopic observations of the surface and geometry of model colloidal gels during desiccation under controlled air flow highlight the role of crack formation in drying. The density of cracks and their rate of appearance depend on the initial solid fraction of the gels and their adherence to the substrate. While under certain conditions cracking leads to an increase of the drying rate, in other cases cracking allows for its conservation over an extended period of the drying process. Nevertheless, as long as the sample is saturated with water, each piece within the sample shrinks isotropically as if it were an independent drying system. By simulating the airflow around the sample and inside the crack cavities, we show the existence of a perturbation in the air velocity in the vicinity of the crack cavity whose scale depends on the aspect ratio (depth/width) of the latter. On this basis, we propose a simple model which predicts the observed drying rate variations encountered while the sample cracks; and further enables to simulate the desiccation for a designated crack density