Localized translational motions in semicrystalline poly(ethylene terephthalate) studied by incoherent quasielastic neutron scattering

Abstract

One of the simplest ways to confine polymeric materials is by self assembling during the crystallization process. The remaining amorphous phase is then constrained by the lamellar crystals. In this manuscript, we aim to shed additional light in the understanding of the amorphous chains dynamics of semicrystalline polymers above the T g by using incoherent quasielastic neutron scattering QENS in a mesoscopic timescale (10 -9 -10 -10 s) on poly(ethylene terephthalate). The observed dynamics is satisfactorily described by a theoretical model that considers that the proton mobility follows a random jump-diffusion in a restricted environment. We demonstrate that the combination of macroscopic with microscopic dynamic tools allows a complete description of the confined dynamics on a paradigmatic semicrystalline polymer like poly(ethylene terephthalate).

Coupling of Caged Molecule Dynamics to JG β-Relaxation II: Polymers

“…Lower panel: Mean square displacement, ⟨ u 2 ⟩, of amorphous PET (black ◇) as measured at the IN10 spectrometer plotted as a function of temperature. Data are from ref and redrawn. Data above 383 K are not shown, being potentially affected by cold crystallization.…”

“…Poly(ethylene terephthalate). Incoherent quasielastic neutron scattering (QENS) measurements were made on amorphous poly(ethylene terephthalate) (PET) at the backscattering spectrometer IN10, at the ILL (Grenoble, France) by Sanz et al 101 The amorphous sample has M w = 45 kg/mol and T gα = 345 K. Following the standard procedure to obtain the mean square displacement, ⟨u 2 ⟩, from the elastic scattering intensity, the results are shown as a function of temperature in the lower panel of Figure 12. The presence of change of Tdependence of ⟨u 2 ⟩ at T HF = 173 K is suggested by intersection of the red and blue dashed lines, which are linear regressions that optimize the data in the temperature ranges from 0 to 178 K and above 178 to above 345 K, respectively.…”

Uncovering a novel transition in the dynamics of proteins in the dry state

“…However, at or below the glass transition temperature Tg of most glass-formers, both the -relaxation and secondary relaxations have characteristic times too long to be observed in this frequency window. The techniques used in this kind of experiments include quasi elastic neutron scattering [7][8][9][10][11][12][13],…”

Constrained and Heterogeneous Dynamics in the Mobile and the Rigid Amorphous Fractions of Poly(dimethylsiloxane): A Multifrequency High-Field Electron Paramagnetic Resonance Study

“…see refs , , and , so that the peak center (or α c relaxation time) is determined in highly crystalline polymers with more difficulty . In the case of neutron scattering experiments with fully protonated SCPs the total scattering cross section is affected by the strong elastic term due to the crystalline phase . In NMR, 1 H spin–spin relaxation is often exploited to distinguish the disordered from the crystalline regions, together with 13 C isotropic chemical shifts .…”