Surface properties and the stability of poly(ethylene terephtalate) films treated in plasmas of helium‐oxygen mixtures

Abstract

In this work, the surface treatment of poly(ethylene terephtalate) (PET) films in a low frequency (70 kHz) discharge in helium-oxygen mixtures is investigated. Optical emission spectroscopy and mass spectrometry are used to analyze the gas phase. Surface properties are analyzed via the X-ray photoelectron spectroscopy (XPS) technique and contact angle measurements. The treatment conditions are optimized in order to obtain a surface functionalization, which would show a reduced ageing effect. The stability of the treated surface via the crosslinking process seems to be closely correlated to the presence of the helium metastable species in the discharge. A very good stability with the ageing time is obtained for samples treated in gaseous mixtures that contain less than 5% O 2 , conditions for which the oxidized polymeric structure seems to be formed on a reinforced crosslinked layer. The very efficient loss of He excited species, for amounts of O 2 higher than a few percent, affects the surface crosslinking. For high quantities of oxygen introduced in the reactor (more than about 50%), a balance is established between the introduction of oxygenated groups and the ablation of the surface. In this case, the surface degradation has, as a consequence, the ageing effect.

Surface characterisation of plasma-modified poly(ethylene terephthalate)

“…Thus atomic oxygen and nitrogen species could be produced and the amounts of them can be enhanced by the so-called "catalytic effect" (dissociative ionisation of the molecular oxygen by collisions with meta-stable He species). All these processes could explain the incorporation of oxygen and nitrogen functionalities [51,52]. Moreover, oxygen functionalities can also be attributed to post-plasma reactions (i.e., to ageing effect): When the polymer surface is exposed to air after plasma treatment the active sites (radical species) generated on the surface will react with the oxygen present in the ambient.…”

Effects of atmospheric pressure helium/air plasma treatment on adhesion and mechanical properties of aramid fibers

“…During the He/air plasma treatment, an intense ultraviolet radiation is emitted, which induces cross-linking reaction on the surface of the brils. Potential cross-linking mechanisms on PPTA surfaces have been proposed [22,[35][36][37].…”

Surface Modification of Organic Polymer Films Treated in Atmospheric Plasmas

“…[3][4][5][6][7][8][9][10][11][12][13][14][15] In wet chemical processing, large amounts of toxic solvents are required. 13 RF vacuum plasma 9 and ion beam techniques are conducted under vacuum, leading to high cost and limiting treatments to batch processing.…”