Surface Functionalization of Polyethylene Granules by Treatment with Low-Pressure Air Plasma.

Hana Šourková,Gregor Primc,Petr Špatenka

doi:10.3390/ma11060885

Abstract

Polyethylene granules of diameter 2 mm were treated with a low-pressure weakly ionized air plasma created in a metallic chamber by a pulsed microwave discharge of pulse duration 180 μs and duty cycle 70%. Optical emission spectroscopy showed rich bands of neutral nitrogen molecules and weak O-atom transitions, but the emission from N atoms was below the detection limit. The density of O atoms in the plasma above the samples was measured with a cobalt catalytic probe and exhibited a broad peak at the pressure of 80 Pa, where it was about 2.3 × 1021 m−3. The samples were characterized by X-ray photoelectron spectroscopy. Survey spectra showed oxygen on the surface, while the nitrogen concentration remained below the detection limit for all conditions. The high-resolution C1s peaks revealed formation of various functional groups rather independently from treatment parameters. The results were explained by extensive dissociation of oxygen molecules in the gaseous plasma and negligible flux of N atoms on the polymer surface.

Highlights

Surface properties of polymers are often inadequate, so they have to be modified prior to further treatment
It was explained in detail that fibrous polymers might interact differently with gaseous plasma compared to interaction with flat materials, such as foils, due to the enormous surface-to-mass ratio [2]
This paper reports on the surface modification of polyethylene granules treated with air plasma sustained in a chamber suitable for semi-industrial applications

Summary

Introduction

Surface properties of polymers are often inadequate, so they have to be modified prior to further treatment. A widely used technique for tailoring the surface properties of polymers is a brief exposure to non-equilibrium gaseous plasma. A possible reason for such discrepancies is the application of polymers in various forms and various grades. It was explained in detail that fibrous polymers might interact differently with gaseous plasma compared to interaction with flat materials, such as foils, due to the enormous surface-to-mass ratio [2]. A commonly used polymer is polyethylene, which comes in different forms and different grades. Orendač et al studied the modification of high-density polyethylene (HDPE) foils by argon plasma to create allyl and polyenyl radicals or dangling bonds [4]

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Conclusion