Naslov
Local Dynamics in Amorphous Aliphatic-Aromatic Copolyamides as Probed by 13C Solid-State NMR

Autori
Petkovic Didovic, Mirna ; Lorthioir, Cedric ; Sotta, Paul ; Fillot, Louise-Anne ; Long, Didier.R.

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
19th European Symposium on Polymer Spectroscopy - Book of Abstracts / - Prag, 2013

ISBN
978-80-85009-77-4

Skup
19th European Symposium on Polymer Spectroscopy

Mjesto i datum
Prag, Češka Republika, 07.07.2013. - 11.07.2013

Vrsta sudjelovanja
Predavanje

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
solid-state NMR; semiaromatic polyamides; relaxations; molecular dynamics; water

Sažetak
The α-relaxation process of polyamides is drastically affected by the absorption of water and other solvents. Dynamics of adsorbed water was previously investigated(1), along with various relaxation processes detected in the amorphous copolyamides. Those dynamical features were mainly probed using broadband dielectric spectroscopy and inelastic neutron scattering. The purpose of the present work is to determine molecular origins underlying these relaxation processes, using a selective and molecular approach, namely solid-state NMR. In particular, the influence of water on polyamide local dynamics is investigated by means of assorted NMR approaches: 13C chemical shift anisotropy, 13C T2 and 1H-13C dipolar coupling measurements. In the case of the dry polyamide, aliphatic carbons are found to be mobile over the tens of microseconds timescale at room temperature, with no significant increase in motional amplitude until an onset of the α-relaxation at 90 °C, demonstrating that aliphatic carbons are not involved in β-relaxation process. Methylene groups in the middle of aliphatic segments proved to be more mobile than those located near the amide groups. In contrast, motional amplitudes of both aromatic and carbonyl carbons are continuously increasing in the same temperature range, indicating that both entities are involved in β-relaxation process. Motions of aromatic rings and carbonyl groups were found to be correlated and a motional model was proposed to describe these local reorientations. Comparison of those results with the ones gained on the wet sample will be presented. Such molecular description should help clarify a mechanism of plasticisation effect of water on polyamides. (1) Lauratti M., Sotta P., Long D.R. et al., Macromolecules 45:1676-1687, 2012.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

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