Effects of atmospheric plasma treatment on adhesion and tribology of aromatic thermoplastic polymers

Abstract

After cold plasma treatment of poly(ethylene terephthalate) and poly(ether‐ether ketone) surfaces by dielectric barrier discharge (DBD) under atmospheric (air) conditions, variations in surface chemistry, and morphology were investigated in relation with adhesion and tribological properties. According to XPS measurements, surface oxidation caused the formation of low molecular weight moieties of carboxylic acids. The latter resulted in more hydrophilic surfaces according to water contact angle measurements, with mainly a higher polar surface energy component. In parallel, the surface roughness of originally polished surfaces reduced due to flattening of local surface asperities after DBD. The DBD significantly improved the adhesive shear strength for different glue types in polymer/polymer and polymer/steel joints, while the best adhesion was observed for a two‐component epoxy type adhesive. Under dry sliding conditions, the coefficients of friction were lower after DBD compared to pristine samples only under mild sliding conditions (v = 0.05 m/s; p < 1 MPa.m/s), while the higher normal loads caused an increase in coefficients of friction likely due to the higher contributions of surface deformation. Most interestingly, the lower coefficients of friction after DBD were observed under oil lubrication and after cleaning the sliding track (“run‐out” condition), due to the better retention of oil at the sliding surface for plasma‐treated polymers. POLYM. ENG. SCI., 58:E93–E103, 2018. © 2017 Society of Plastics Engineers

Selective Grafting of Polyamines to Polyether Ether Ketone Surface during Molding and Its Use for Chemical Plating

“…An efficient method with high industrial relevance is flame impingement. Treatment with defined plasmas, e.g., low pressure plasma, atmospheric plasma, or corona, in the presence of different gases gives a better control of chemical modification [5][6][7][8][9][10][11][12][13][14][15][16][17]. However, only the PEEK segments on the outermost surface layer are converted to functional groups like carboxyl, hydroxyl, carbonyl, and amide.…”

Tribological Behaviour of Polymers in Terms of Plasma Treatment: A Brief Review

“…In contrast, our last work [73] elaborated on the effect of atmospheric DBD plasma on the tribological behaviour of PET under various test conditions (3 "dry" normal load and "run-out lubrication" constant normal load conditions). The effect of DBD plasma treatment on the characterization of the surface was interpreted as an enhancement of the surface energy and reduction in the surface roughness due to the melting of surface asperities.…”

Adhesion Improvement of Thermoplastics-Based Composites by Atmospheric Plasma and UV Treatments

“…Polar oxygen groups are created on the surface by the radicals reacting with oxygen in the air. Al-Maliki et al [11] determined that post-treatment there was an increase in oxygen content and a decrease in carbon content forming polar functional groups that increased the wettability of the surface thus making the surface more hydrophilic. They attributed plasma treatment's ability to increase surface energy to the combination of two main factors, increased wettability and increased surface roughness.…”

“…The change in surface roughness may be different depending on the type of treatment used. In [11] and [13] it was found that using dielectric-barrier discharge (DBD) treatment for one minute causes a flattening of the surface rather than a roughening. Hergelová et al [14] again found that short treatment times caused flattening, but with extended treatment time, the roughness would start to increase rapidly.…”