Two methods—attenuated total reflection Fourier infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS)—have been used to analyze the chemical structure of polytetrafluorethylene (PTFE) thin coatings deposited by pulsed laser (PLD) and pulsed electron beam (PED) ablations. The volume of the analyzed materials is significantly different in these techniques which can be of great importance in the characterization of highly heterogeneous thin films. Optical microscopy, atomic force microscopy (AFM) and scanning electron microscopy (SEM) have been additionally used to examine the coating surface morphology. The studies have shown that in the case of thin polymer coatings deposited by physical methods, the application for chemical structure evaluation of complementary techniques, with different surface sensitivity, together with the use of surface topography imaging, provide unique insight into the film morphology. The results can provide information contributing to an in-depth understanding of the deposition mechanism of polymer coatings.
Poly(ethylene-co-vinyl acetate) (EVA) films were deposited for the first time using physical methods. The chemical structure of the films obtained using two techniques, pulsed electron beam deposition (PED) and pulsed laser deposition (PLD), was studied by attenuated total reflection Fourier infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS). Whilst significant molecular degradation of the EVA films was observed for the PLD method, the original macromolecular structure was only partially degraded when the PED technique was used, emphasizing the superiority of the PED method over PLD for structurally complex polymers such as EVA. Optical and scanning electron microscopic observations revealed compact and smooth EVA films deposited by pulsed electron beam ablation as opposed to heterogeneous films with many different sized particulates obtained by PLD.
The goal of this work was to assess the suitability of a commercial synthetic skin to simulate occluded human skin friction behaviour in dry and moist skin conditions and under different applied surface pressures, with the view to using this material as a tribological test-bed for healthcare and personal care devices that are in direct contact with the skin during use. A flat rotating ring friction measurement device, in which one part of the skin surface is continuously covered (i.e. occluded), was used to compare the friction behaviour of human skin and the synthetic skin in controlled nominally dry and nominally moist skin conditions. Three loading levels were tested, simulating light, medium and high skin pressures typical of many lifestyleand personal health-related applications. The results showed that the friction behaviour of the synthetic skin tested here was notably different to that of human skin in vivo in terms of the effects of skin hydration, sliding time and applied surface pressure. It is concluded that, for use as a tribological test-bed, the tested synthetic skin model does not provide an acceptable alternative to in vivo tests using human skin.
For the first time pulsed electron beam deposition (PED) was used to deposit thin films composed of polymer‐carbon composite material. The targets were polypropylene‐carbon (PP/C) composites, with different carbon fillers: carbon black, nanotubes, or graphene. It was confirmed that coatings with composite structure were obtained – the PED method enables complex structures, including nanotubes, to be ablated whole from the target, transported toward substrate, and incorporated into the polymer matrix. These breakthrough results can contribute significantly to improved understanding of the mechanism of electron beam ablation of polymer and composite materials, and open up new possibilities for the deposition of complex composite thin films for use in, for example, advanced sensor applications.
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