1,721,037 research outputs found
Modelling Sorption and Transport of Gases in Polymeric Membranes across Different Scales: A Review
Full text linkProfessor Giulio C. Sarti has provided outstanding contributions to the modelling of fluid sorption and transport in polymeric materials, with a special eye on industrial applications such as membrane separation, due to his Chemical Engineering background. He was the co-creator of innovative theories such as the Non-Equilibrium Theory for Glassy Polymers (NET-GP), a flexible tool to estimate the solubility of pure and mixed fluids in a wide range of polymers, and of the Standard Transport Model (STM) for estimating membrane permeability and selectivity. In this review, inspired by his rigorous and original approach to representing membrane fundamentals, we provide an overview of the most significant and up-to-date modeling tools available to estimate the main properties governing polymeric membranes in fluid separation, namely solubility and diffusivity. The paper is not meant to be comprehensive, but it focuses on those contributions that are most relevant or that show the potential to be relevant in the future. We do not restrict our view to the field of macroscopic modelling, which was the main playground of professor Sarti, but also devote our attention to Molecular and Multiscale Hierarchical Modeling. This work proposes a critical evaluation of the different approaches considered, along with their limitations and potentiality
Evaluating sustainable materials for membrane separations through molecular simulations: the case of Polyxydroxyalkanoates (PHA)
No full textPolyxydroxyalkanoates (PHA) are a family of linear optically active semi-crystalline polyesters produced by bacterial fermentation, known for their overall sustainability, including biodegradability and biocompatibility. PHA are also characterized by thermoplasticity and good mechanical properties, comparable to those of commercially relevant standard polymers.
The gas transport properties of these materials are still scarcely characterized experimentally, and their determination is complicated by a number of uncertainty sources, such as a time-dependent degree of crystallinity. In this study we aim at evaluating the physicochemical and transport properties of such materials with molecular simulations, to gain information about their applicability in the membrane gas separation field. In order to draw correlation between the molecular structure and the performance of these materials, three homopolymers and two copolymers of the PHA family were considered:
• poly(3-hydroxybutyrate) (P3HB);
• poly(3-hydroxyvalerate) (P3HV);
• poly(4-hydroxybutyrate) (P4HB);
• poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV);
• poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (PHBB).
Molecular models of each material were simulated using Molecular Dynamics (MD), obtaining amorphous density and solubility parameter values, that were successfully validated with experimental data found in literature. The simulated values of radius of gyration, accessible free volume, density, cohesive energy and elastic modulus in the different copolymers were correlated to their chemical composition.
Sorption and diffusion in the polymers were then analysed for three gases, O2, CH4 and CO2, by means of Grand Canonical Monte Carlo (GCMC) and MD simulations. The results were compared with experimental values, obtained through permeation tests at different temperatures, performed on PHBV with 8% of 3-hydroxyvalerate monomers purchased from Merck-Sigma
An Insight on the Membrane-Based Separation of CO2/CO Mixtures for CO2 Capture and Utilisation Processes: Tradeoff, Limits and Opportunities
No full textA multiscale method to predict the mixed gas performance of polymeric membranes for CO2 capture
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