To improve temperature durability for autoclaving of SiO x diffusion barrier coatings on polypropylene, plasma polymerized hexamethyldisiloxane (pp-HMDSO) is applied by plasma enhanced chemical vapour deposition as interlayer material and compared with results obtained with amorphous hydrogenated carbon-nitrogen (a-C : N : H) and a-Si : C : O : N : H interlayers. The influence of the O 2 /HMDSO ratio on the chemical structure and related mechanical and oxygen barrier properties is investigated by fragmentation tests, dilatometry, oxygen transmission rate, internal stress and mass density measurements as well as Fourier transform infrared and x-ray photoelectron spectroscopy. Carbon-rich, polymer-like coatings with low density, low internal stress and excellent adhesive and cohesive properties are found for pp-HMDSO at the expense of barrier performance. In the SiO x /pp-HMDSO coating a broad transition in chemical composition was observed, explaining improved mechanical properties responsible for good barrier performance after thermal cycling or autoclaving.
The precipitation of solid-state sphere-like nanostructures from an organosilicon precursor at atmospheric pressure is investigated with the prospect of improving powder flowability by the attachment of nanoscopic spacers to the powder particles' surfaces. Tetramethylsilane (TMS) is admixed to the afterglow of a low power (<0.5 W) barrier discharge (BD). The BD occurs in a single miniature flow channel, where Ar or He enriched with O2 is excited favouring homogeneous gas phase reactions of atomic oxygen and TMS in the afterglow. The chemical and morphological influence of Ar or He on the formation of nanostructures is explored at two positions in the afterglow by Fourier transform infrared spectroscopy and scanning electron microscopy. For the Ar-based BD, larger spherical nanostructures (100–1000 nm) of higher oxide content are obtained, while for He polymeric deposits with characteristic sizes below 100 nm are found. In addition, the processing capability of a BD device, consisting of a set of 64 miniature flow channels, is probed by means of the wettability improvement of polymer powder particles, conveyed through the BD afterglow zone of a multi-channel device. The treatment is shown to decrease the benzyl alcohol contact angle significantly with increasing oxygen feed.
The improvement of temperature durability for autoclaving of silicon oxide (SiOx) diffusion barrier coatings on poly(propylene) (PP) by deposition of thin amorphous hydrogenated carbon‐nitrogen (a‐C:N:H) intermediate layers was investigated. Attenuated total reflection Fourier transform infrared (ATR‐FTIR) spectroscopy revealed terminating amino and nitrile groups responsible for low compressive stress in a‐C:N:H. Uniaxial tensile tests showed a higher crack onset strain (COS) for a‐C:N:H of 2.7% compared to 0.7% for SiOx. Best temperature durability was achieved by a three‐layer coating from a‐C:N:H, an intermediate layer deposited by a mixture of N2, C2H2, hexamethyldisiloxane (HMDSO), and a SiOx layer. The oxygen transmission rate (OTR) was only increased from 6 to 22 cm3·m−2·d−1·bar−1 after exposure to 140 °C for 30 min, whereas for single SiOx barrier coatings, severe loss of barrier properties of 1 040 cm3·m−2·d−1·bar−1 was evidenced due to the formation of cracks.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.