A thermodynamic modeling approach for dynamic softening in glassy amorphous polymers

Modeling the viscoelastoplastic behavior of amorphous glassy polymers

Constitutive equations are derived for the viscoelastoplastic response of amorphous glassy polymers at isothermal loading with small strains. A polymer is treated as an ensemble of cooperatively relaxing regions (CRR) which rearrange at random times as they are thermally agitated. Rearrangement of CRRs reflects the viscoelastic response of the bulk medium. At low stresses, CRRs are connected wi...

Diffusion of Small Molecules in Amorphous Glassy Polymers

Thermodynamic Modeling of Gas Transport in Glassy Polymeric Membranes

Solubility and permeability of gases in glassy polymers have been considered with the aim of illustrating the applicability of thermodynamically-based models for their description and prediction. The solubility isotherms are described by using the nonequilibrium lattice fluid (NELF) (model, already known to be appropriate for nonequilibrium glassy polymers, while the permeability isotherms are ...

Softening and yielding of soft glassy materials.

Solids deform and fluids flow, but soft glassy materials, such as emulsions, foams, suspensions, and pastes, exhibit an intricate mix of solid- and liquid-like behavior. While much progress has been made to understand their elastic (small strain) and flow (infinite strain) properties, such understanding is lacking for the softening and yielding phenomena that connect these asymptotic regimes. H...

Craze initiation in glassy polymers

In this work a method is presented that can be used to predict craze initiation in glassy polymers. The approach is based on the view that the development of a craze is preceded by de formation of a localised plastic deformation zone. As this zone develops, the hydrostatic stress increases, and, when exceeding a critical stress level, cavitation will take place, leading to local development of ...