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

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.

Preparation and rheological study of pentaerythritol triacrylate grafted onto polypropylene induced by air plasma

“…The reason is that the dissociation energy of N 2 molecules is higher than that of O 2 molecules, so that the density of nitrogen atoms in the plasma system is much lower than that of oxygen atoms. On the other hand, polymer surface treated also has a higher affinity for reactions with oxygen atoms than nitrogen atoms …”

Plasma Activation of Polyethylene Powder

“…Samples were treated in a semi-industrial reactor for the treatment of polymer powders LA400 produced by Surface-Treat Ltd. (Turnov, Czech Republic). Details of the reactor are given elsewhere [ 14 ]. Briefly, the reactor is a rectangular vacuum vessel of a volume of 64 L made from aluminum.…”

“…A comprehensive review was published recently by Arpagaus et al [ 9 ]. The possible solutions include the fluidization [ 10 , 11 ], rotation [ 12 ], vibration and conveying [ 13 ] and stirring [ 14 , 15 ]. All these techniques allow for mixing the powder upon plasma treatment and enable reasonably uniform treatment of all particles in a batch.…”

Plasma treatment of polymer powders – from laboratory research to industrial application

“…Šourková et al [180] 2018, Pavlatova et al [145] 2012, Špatenka et al [10,22,23] 2016, Czech Republic PMMA, respectively. The N/C atomic ratio increased with treatment time and reached a maximum of approximately 0.1 and 0.15 after about 30 min.…”

“…To characterize the LA400 more detailed, Šourková et al treated PE granules of 2 mm diameter for 1 min in air plasma under pulsed MW conditions (pulse duration 180 μs and duty cycle 70%) and characterized the plasma by OES and a laser‐heated fiber‐optics catalytic probe. The polymer granules were filled in a cup (20 cm diameter, 7 cm height) to a height level of about 1 cm while continuous mixing.…”