The surface modification of polyethylene terephthalate (PET) polymer films has been performed by irradiation of extreme ultraviolet photons to investigate the effect of surface structuring on wettability control. For biomedical engineering applications, surface structuring and wettability control of PET films could enhance the polymer biocompatibility by promoting cell adhesion and consequently proliferation. The PET films are irradiated with laser plasma extreme ultraviolet source based on double stream gas puff target under different environments. The extreme ultraviolet modified PET film surfaces are characterized by atomic force microscopy and WCA goniometer. The extreme ultraviolet surface modification resulted in the formation of nano-and microstructuring on the polymer surfaces. The surface structuring consequently increased WCA making the PET surfaces more hydrophobic. The results demonstrate the direct relationship between surface roughness and hydrophobicity for extreme ultraviolet modified PET samples.
The article presents a discussion on the use of hexagonal boron nitride as an additive to lubricants. Based on the analysis of the research, factors determining its application were identified. These include particle size distribution, their morphology, specific surface area, and porosity. Next, the research identifying these properties for the four types of h-BN was described. Based on the results, the possible mechanisms of the influence of individual h-BN types were described. It was also found that the use of h-BN nanoparticles as lubricants seems to be promising.
Purpose -The purpose of this paper is to study the sliding and the vibrating fretting tests mechanism of h-BN micro-particles when used as a lubricating grease-2 additive. Design/methodology/approach -The fretting tests were conducted on steel/steel contacts using both vibrating fretting apparatus and the shaftsleeve slide fitted tester. The wear scars were characterized with profilometry. The tribological properties of grease-2 compounded with h-BN additive were also compared to those obtained for the commercial product Militec-4. Findings -The experiment showed significant differences between the results obtained from the vibrating fretting and the shaft-sleeve sliding fitted tests. Adding h-BN to the lubricant leads to a better performance in the shaft-sleeve slide regime than in the steel/steel vibrating test condition. Originality/value -The results of the experimental studies demonstrate the potential of h-BN as an additive for preventing fretting sliding, and can very useful for further application of compound grease-2 with h-BN additive in industrial equipment.
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