Improvement of Water Barrier Properties of Poly(ethylene-co-vinyl alcohol) Films by Hydrophobic Plasma Surface Treatments

Abstract

Poly(ethylene-co-vinyl alcohol) (EVOH) films with two different ethylene contents (29 and 44 mol %) have been treated by hydrophobic plasma (CF4, tetramethylsilane (TMS), CF4/H2, and CF4/C2H2). Conditions of the cold plasma treatment were optimized by the water contact angle measurements as a function of the different plasma parameters (plasma power, gas flow, and treatment time). Chemical changes of the film surface were characterized by X-ray photoelectron spectroscopy. The obtained results revealed the presence of fluorine containing functional groups such as CF, CF2, and CF3 in the case of CF4, CF4/H2, and CF4/C2H2 plasma treatment and the presence of SiO x C y compounds after TMS treatment. The morphology of the plasma treated EVOH films was examined by atomic force microscopy, which indicated an increase of the film roughness after treatment. Negligible changes of thermal properties of the modified EVOH films were observed by means of the temperature modulated differential scanning calorimetry. The barrier properties of films were characterized by water permeability measurements. It was found that the hydrophobicity was significantly improved after plasma treatment and for some treated films the water permeability was decreased up to 28%.

Effect of mechanical, barrier and adhesion properties on oxygen plasma surface modified PP

“…It was related primarily to the structure of the film and particularly to the density which was connected to the degree of crystallinity and also to the stiffness of the film (Tenn et al, 2012). In Fig.…”

Cold Plasma‐Mediated Treatments for Shelf Life Extension of Fresh Produce: A Review of Recent Research Developments

“…Other antimicrobial substances such as chitosan, silver, catalyst TiO 2 , and trichlosan have also been immobilized on film surfaces through plasma‐assisted deposition (Assis & Hotchkiss, ; Jung, Kim, Gweon, Moon, & Choe, ). In addition, depositing a thin layer of SiO x C y groups on film surface by hydrophobic plasma treatments, which can result in a lesser atomic composition of carbon than untreated films, is another method to reduce the permeability of water vapor (Tenn et al., ).…”

“…Other antimicrobial substances such as chitosan, silver, catalyst TiO 2 , and trichlosan have also been immobilized on film surfaces through plasma-assisted deposition (Assis & Hotchkiss, 2007;Jung, Kim, Gweon, Moon, & Choe, 2010). In addition, depositing a thin layer of SiO x C y groups on film surface by hydrophobic plasma treatments, which can result in a lesser atomic composition of carbon than untreated films, is another method to reduce the permeability of water vapor (Tenn et al, 2012). Despite the above positive results, the literature also reveals that the desired changes in plasma-induced properties cannot always be well maintained with the extension of posttreatment storage time, and sometimes totally reversal changes could occur (Gotoh, Yasukawa, & Taniguchi, 2012;Pankaj & Thomas, 2016).…”

Multifunctional hydrolyzed EVA membranes with tunable microstructure and water barrier properties

“…In addition, the dependence of diffusion coefficient D on the concentration of permeant C inside the polymer is generally due to the increase of the free volume (plasticization) and to clustering. In order to consider the former phenomenon, numerous models have been proposed, but the equation, which considers an exponential relation is the most popular [22,30,41,[60][61][62][63], probably for its simplicity and for the well concordance with experimental data usually obtained. Moreover, the equation presents compatibility with the free volume theory that is often used to describe the diffusion of the molecular species in a polymer at temperature above their T g .…”

“…EVOH copolymers are materials composed of hydrophobic and hydrophilic segments, thus the chemical composition of EVOH copolymer (i.e. ethylene and VOH contents) affects several properties such as mechanical properties, moisture sensitivity and processability [29][30][31][32]. However, these EVOH copolymers have a semicrystalline structure irrespective of their composition and depending on the VOH content three crystalline systems have been reported: orthorhombic latticefor 0-20 mol% of VOH; pseudohexagonal lattice -for a composition range between 20 and 60 mol% of VOH and monoclinic lattice for VOH 460 mol% [33,34].…”