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Abstract
The research presented here aimed at modeling gas transport properties in semi-crystalline polymers with particular attention to hydrogen gas.
The first part of the work was dedicated to developing a multi-scale modeling approach for evaluating gas sorption in semi-crystalline High-Density Polyethylene which couples Lattice-Fluid theory with Molecular Dynamics simulations. The model belongs to the so-called 'constraint pressure models' which implicitly describe the perturbation induced by the impermeable crystalline domains on the amorphous matrix using a fictitious constraint pressure parameter. The second and main part of the work focused on the molecular reproduction and simulation of the explicit semi-crystalline material accounting for different intercalations between the two phases (surface fraction of tie-chains). Quantitative information on hydrogen sorption and diffusion coefficients were derived using Widom test particle insertion method and the Mean Square Displacement analysis coupled with a macroscopic model for the estimation of the crystallites' induced tortuosity, respectively. The permeability coefficient was finally estimated according to the solution-diffusion model. The results were in agreement with the experimental results obtained in an experimental campaign that was conducted in parallel and other literature references.
Abstract
The research presented here aimed at modeling gas transport properties in semi-crystalline polymers with particular attention to hydrogen gas.
The first part of the work was dedicated to developing a multi-scale modeling approach for evaluating gas sorption in semi-crystalline High-Density Polyethylene which couples Lattice-Fluid theory with Molecular Dynamics simulations. The model belongs to the so-called 'constraint pressure models' which implicitly describe the perturbation induced by the impermeable crystalline domains on the amorphous matrix using a fictitious constraint pressure parameter. The second and main part of the work focused on the molecular reproduction and simulation of the explicit semi-crystalline material accounting for different intercalations between the two phases (surface fraction of tie-chains). Quantitative information on hydrogen sorption and diffusion coefficients were derived using Widom test particle insertion method and the Mean Square Displacement analysis coupled with a macroscopic model for the estimation of the crystallites' induced tortuosity, respectively. The permeability coefficient was finally estimated according to the solution-diffusion model. The results were in agreement with the experimental results obtained in an experimental campaign that was conducted in parallel and other literature references.
Tipologia del documento
Tesi di dottorato
Autore
Atiq, Omar
Supervisore
Dottorato di ricerca
Ciclo
36
Coordinatore
Settore disciplinare
Settore concorsuale
Parole chiave
semi-crystalline polymers
molecular modeling
hydrogen
thermodynamic modeling
sorption
diffusion
permeation
URN:NBN
Data di discussione
15 Marzo 2024
URI
Altri metadati
Tipologia del documento
Tesi di dottorato
Autore
Atiq, Omar
Supervisore
Dottorato di ricerca
Ciclo
36
Coordinatore
Settore disciplinare
Settore concorsuale
Parole chiave
semi-crystalline polymers
molecular modeling
hydrogen
thermodynamic modeling
sorption
diffusion
permeation
URN:NBN
Data di discussione
15 Marzo 2024
URI
Gestione del documento: