Buscar

Estamos realizando la búsqueda. Por favor, espere...

Crosslinked networks in electron beam irradiated polyethylenes evaluated by proton low-field NMR spectroscopy

Abstract: Effect of electron beam (EB) irradiation is analyzed in low and high density polyethylenes (LDPE and HDPE, respectively) at different doses. Parameters as important as degree of crystallinity, melting or crystallization temperatures are dependent on the initial PE molecular architecture, which also controls the gel content developed by action of EB irradiation and the EB dose applied. Thus, this gel amount, ascribed to formation of chain crosslinkings, is raised as irradiation dose increases, being larger in the HDPE than in the LDPE. In both, a plateau value is reached at the highest doses. The molecular changes that take place in both PEs during EB irradiation lead to a hindrance in their crystallization capacity, once macrochains are molten, and, accordingly, to a reduction in crystallinity and to formation of thinner crystallites. Variation with temperature of rigid and soft fractions together with their respective relaxation times is followed in the irradiated LDPE and HDPE specimens by pulse mixed magic-sandwich echo nuclear magnetic resonance (MSE-NMR) measurements. The network structure promoted in these PEs is evaluated by using the multiple-quantum nuclear magnetic resonance (MQ-NMR) approach, showing important differences caused by EB irradiation due to their intrinsic molecular characteristics.

 Autoría: Posadas P., Valentín J.L., Benavente R., Blázquez-Blázquez E., Urtiaga A., Álvarez J.A., Cerrada M.L.,

 Fuente: Radiation Physics and Chemistry, 2023, 204, 110694

 Editorial: Oxford: Pergamon

 Fecha de publicación: 01/03/2023

 Nº de páginas: 10

 Tipo de publicación: Artículo de Revista

 DOI: 10.1016/j.radphyschem.2022.110694

 ISSN: 0969-806X,1879-0895

 Proyecto español: PID2020-119047RB-I00

 Url de la publicación: https://doi.org/10.1016/j.radphyschem.2022.110694

Autoría

POSADAS, PILAR

VALENTÍN, JUAN L.

BENAVENTE, ROSARIO

BLÁZQUEZ BLÁZQUEZ, ENRIQUE

JUAN ANDRES ALVAREZ BALLESTEROS

CERRADA, MARÍA LUISA