Effects of ionizing radiation in ethylene‐vinyl alcohol copolymers and in composites containing microfibrillated cellulose

Abstract

This study reports on the effect of gamma radiation on morphological, thermal, and water barrier properties of pure ethylene vinyl alcohol copolymers (EVOH29 and EVOH44) and its biocomposites with the nanofiller microfibrillated cellulose (2 wt %). Added microfibrillated cellulose (MFC) preserved the transparency of EVOH films but led to a decrease in water barrier properties. Gamma irradiation at low (30 kGy) and high doses (60 kGy) caused some irreversible changes in the phase morphology of EVOH29 and EVOH44 copolymers that could be associated to crosslinking and other chemical alterations. Additionally, the EVOH copolymers and the EVOH composites reduced the number of hygroscopic hydroxyl functionalities during the irradiation processing and novel carbonyl based chemistry was, in turn, detected. As a result of the above alterations, the water barrier properties of both neat materials and composites irradiated at low doses were notably enhanced, counteracting the detrimental effect on water barrier of adding MFC to the EVOH matrix.

Nanocellulose in Thin Films, Coatings, and Plies for Packaging Applications: A Review

“…The performance of various nanocellulose-based films to resist permeation by oxygen is summarized in Table B of the Appendix. Use of a separate moisture barrier (Lagaron et al 2004) Chemical modification of the cellulose (Visanko et al 2015) Coupling agents (Eichhorn et al 2009;Faruk et al 2012) Waxes on NFC film (Spence et al 2011b) Plasticizer in NFC film (Bayati et al 2014;Arrieta et al 2015) Curable cross-linking (Fernandez et al 2008;Raghu 2015) Film performance is compromised by high humidity or moisture.…”

“…Chemical reactions to cure and insolubilize a matrix polymer, usually by some form of cross-linking, have been used as a means to decrease the moisture-sensitivity of nanocellulose-containing barrier layers (Fernandez et al 2008;Aulin and Ström 2013;Raghu 2015). Fernandez et al (2008) employed gamma irradiation to cure ethylene vinyl alcohol films incorporating MFC as a reinforcement.…”

“…Fernandez et al (2008) employed gamma irradiation to cure ethylene vinyl alcohol films incorporating MFC as a reinforcement. The water barrier properties of the films were enhanced by the gamma radiation treatment.…”

Functionalized Polymers from Lignocellulosic Biomass: State of the Art

“…Although the vast majority of reports are focused on MFC's ability to reinforce [79][80][81][82][83][84][85][86][87] and toughen [85][86][87][88][89][90][91] polymer matrices, there is an increasing number of publications dedicated to the superior barrier properties of MFC for packaging materials [76,84,[92][93][94][95][96][97][98][99]. The recent reviews of Siró et al [97], Lavoine et al [98] and Johansson et al [99] give an overview of these competitive nanomaterials.…”

10 Swelling and barrier properties

“…Diffusion coefficients of water were determined for ethylene vinyl alcohol copolymers and related composites reinforced with 2 wt% MFC (Fernández et al, 2008). They were estimated from the desorption curves for samples conditioned at 100% RH (water sorption) and subsequently desorbed by conditioning at 0% RH.…”