We study by dielectric spectroscopy the molecular dynamics of relaxation processes during plastic flow glassy polymers up to strain hardening regime for three different protocols deformation. The measured spectra cover 4 decades in frequencies and allow us measure evolution as a function applied dominant time τα width wτ distribution times. first protocol is performed at constant rate λ̇. confir...

We investigate, using numerical simulations and analytical arguments, a simple one dimensional model for the swelling or the collapse of a closed polymer chain of size N , representing the dynamical evolution of a polymer in a Θ-solvent that is rapidly changed into a good solvent (swelling) or a bad solvent (collapse). In the case of swelling, the density profile for intermediate times is parab...

Poly-Carbonate (PC) and Poly-Methyl-Methacrylate (PMMA) are lightweight and mechanically tough transparent glassy polymers. Their mechanical behavior at low to moderate strain rates has been well characterized; however, that at high strain rates needs additional work. We propose two modifications to existing pressure-dependent viscoplastic constitutive equations that enable one to simulate bett...

When two immiscible polymers are brought into intimate contact, highly localized mixing of polymer chains creates an “interphase” region. We have fabricated materials that are entirely interphase by forced assembly of two immiscible polymers. Assemblies of thousands of alternating layers of two polymers, with individual layer thickness on the nanometer size scale of the interphase, were created...

The transport of gases in glassy polymeric membranes has been analyzed by means of a fundamental approach based on the nonequilibrium thermodynamic model for glassy polymers (NET-GP) that considers the penetrant chemical potential gradient as the actual driving force of the diffusional process. The diffusivity of a penetrant is thus described as the product of a purely kinetic quantity, the pen...