Radek Prikryl

Plasma surface treatment and modification of glass fibers

New helical coupling plasma system for continuous surface treatment and modification (surface processing) of fiber bundles has been developed and tested for glass fibers. The system enables surface processing of single filaments and flat substrates as well. Surface processed glass fibers and their bundles were examined as reinforcements for glass fiber/polyester composite systems. Processing of fibers comprised a surface treatment using argon gas and a surface modification using hexamethyldisiloxane and vinyltriethoxysilane monomers. Interfacial and interlaminar shear strengths of plasma processed glass fiber/polyester systems were compared with those of untreated and commercially sized fibers.

The influence of surface modifications of glass on glass fiber/polyester interphase properties

Unsized glass fibers and planar glass substrates were subjected to low temperature plasma or wet-chemical process to modify the fiber or substrate surface and thus influence the interphase properties of the glass/polyester system. Plasma-polymerized thin films (interlayers) of organosilicon monomers (hexamethyldisiloxane and vinyltriethoxysilane) were deposited in an RF helical coupling plasma system on the glass surface. Commercial silane coupling agent (vinyltriethoxysilane) was coated onto an unmodified glass surface from an aqueous solution. Bonding at the glass/interlayer interface was analyzed by employing a micro-scratch tester together with an optical polarizing microscope for the planar samples. The results revealed that the adhesion bonding could be controlled by plasma process parameters. Scanning electron and atomic force microscopies enabled characterization of the film surface morphology. Chemical composition and chemical structure of prepared interlayers were characterized using X-ray photoelectron and infrared spectroscopies. Microcomposites (macrocomposites) were tested to evaluate the interfacial shear strength (short-beam strength) of the glass fiber/polyester interphase using the microbond test (short-beam shear). Our study indicated that the most efficient interphase could be prepared by plasma polymerization or wet-chemical process using the vinyltriethoxysilane monomer. The short-beam strength was 110% higher than that for untreated fibers in both cases.

XPS study of siloxane plasma polymer films

Abstract Plasma polymer films were deposited from hexamethyldisiloxane (HMDSO), dichloro(methyl)phenylsilane (DCMPS) and vinyltriethoxysilane (VTEO) on polished silicon wafers using a RF helical coupling deposition system. The composition of elements in the surface region (top 6–8 nm) of the deposited films was studied by X-ray-induced photoelectron spectroscopy (XPS) on an ADES 400 VG Scientific photoelectron spectrometer using MgK α (1253.6 eV) or AlK α (1486.6 eV) photon beams at the normal emission angle. Aging effects of plasma-polymerized (PP) HMDSO and DCMPS films stored under standard laboratory conditions were investigated by employing XPS. Post-deposition contamination and oxidation of pp-DCMPS and pp-HMDSO film was carefully observed. An increase in oxygen atoms on the film surface over time is accompanied by changes in bulk atomic concentrations. Sequential sputtering with an Ar ion-beam, together with XPS analysis, was used to measure concentration depth profiles in pp-HMDSO and pp-DCMPS films.

Functional interlayers in multiphase materials

Properties of a three-dimensional interlayer formed between the reinforcement (fiber) and the matrix are final properties of composite materials. It means that surface properties, chemistry of the coated fiber and the matrix play a very important role for achieving good adhesion (a primary factor for stress transfer from the matrix to the fiber) and strong bonding between the fiber and the matrix (to gain the best possible composite mechanical properties). The aim of this work was to prepare thin films with siloxane structure by glow discharge polymerization technique, and the film serves in the end as an adhesion interlayer between the glass fiber and the polyester resin. Plasma polymerized dichloro(methyl)phenylsilane, hexamethyldisiloxane and vinyltriethoxysilane thin films were deposited on the surface of glass slides, silicon wafers and glass fibers. Chemical composition of the plasma polymers on planar substrates was examined by Fourier transform infrared and X-ray photoelectron spectroscopies, surface morphology was studied by atomic force microscopy and surface properties were evaluated by contact angle measurements as the free surface energy. Adhesion between the plasma polymerized film and the glass slide was tested using fully PC-controlled scratch tester with the Rockwell diamond tip. Performance of glass fiber/polyester composite was assessed using a short beam shear and the test revealed that the plasma-polymerized vinyltriethoxysilane interlayer was the best and the interlaminar shear strength was 75% higher than that for untreated fibers.

Thermal properties of an erythritol derivative

Erythritol (C4H10O4) is a sugar alcohol (or polyol) that is commonly used in the food industry. Its molar mass is 122.12 g·mol−1 and mass density 1450 kg·m−3. Erythritol, an odorless crystalline powder, can also be characterized by other physical parameters like melting temperature (121 °C) and boiling temperature (329 °C). The substance can be used for the accumulation of energy in heat exchangers based on various oils or water. The PlusICE A118 product manufactured by the PCM Products Ltd. company (melting temperature Θ = 118 °C, specific heat capacity cp = 2.70 kJ.K−1.kg−1, mass density 1450 kg·m−3, latent heat capacity 340 kJ.kg−1, volumetric heat capacity 493 MJ.m−3) is based on an erythritol-type medium. Thermal properties of the PlusICE A118 product in both solid and liquid phase were investigated for this purpose in terms of potential applications. Temperature dependences of its thermal parameters (thermal diffusivity, thermal conductivity, and specific heat) were determined using a transient (ste...

Basic characteristics of the a-SiOC:H thin films prepared by PE CVD

Hydrogenated amorphous silicon oxycarbide (a-SiOC∶H) thin films were prepared by plasmaenhanced chemical vapor deposition (PE CVD) using an RF helical coupling pulsed-plasma system. Films of the thickness ranging from 210 nm to 1.4 μm were deposited on silicon wafers from vinyltriethoxysilane (VTES) precursor. The thickness of plasma-polymerized films was measured by a Profilometer Talystep using a defined seratch in the layer as deep as the substrate. The deposition rate was observed with respect to the effective power used and the determined dependence could be explained on a basis of the competitive ablation and polymerization mechanisms. Very high deposition rates as far as about 110 nm/min could be reached if proper deposition conditions were tuned. The elemental composition of thin films were studied by conventional and resonant Rutherford Backscattering Spectrometry (RBS) and Elastic Recoil Detection Analysis (ERDA) methods. The Si, C and O bulk content was correlated with the surface one determined from analyses of the photoelectron spectra using X-ray Photoelectron Spectroscopy (XPS).

Protective Properties of a Microstructure Composed of Barrier Nanostructured Organics and SiOx Layers Deposited on a Polymer Matrix

The SiOx barrier nanocoatings have been prepared on selected polymer matrices to increase their resistance against permeation of toxic substances. The aim has been to find out whether the method of vacuum plasma deposition of SiOx barrier nanocoatings on a polyethylene terephthalate (PET) foil used by Aluminium Company of Canada (ALCAN) company (ALCAN Packaging Kreuzlingen AG (SA/Ltd., Kreuzlingen, Switzerland) within the production of CERAMIS® packaging materials with barrier properties can also be used to increase the resistance of foils from other polymers against the permeation of organic solvents and other toxic liquids. The scanning electron microscopy (SEM) microstructure of SiOx nanocoatings prepared by thermal deposition from SiO in vacuum by the Plasma Assisted Physical Vapour Deposition (PA-PVD) method or vacuum deposition of hexamethyldisiloxane (HMDSO) by the Plasma-enhanced chemical vapour deposition (PECVD) method have been studied. The microstructure and behavior of samples when exposed to a liquid test substance in relation to the barrier properties is described.

Study of the thermal properties of selected PCMs for latent heat storage in buildings

The paper is focused on measurements of thermal properties of selected phase change materials (PCMs) which can be used for latent heat storage in building structures. The thermal properties were measured by the transient step-wise method and analyzed by the thermal spectroscopy. The results of three different materials (RT18HC, RT28HC, and RT35HC) and their thermal properties in solid, liquid, and phase change region were determined. They were correlated with the differential scanning calorimetry (DSC) measurement. The results will be used to determine the optimum ratio of components for the construction of drywall and plasters containing listed ingredients, respectively.

Plasmachemical Conservation of Corroded Metallic Objects

Plasmachemical process for conservation of metallic objects is a new way of effective and fast treatment of corroded objects. This process consists of two main steps: corrosion removal and deposition of a protecting film. Removal of corrosion products is based on plasmachemical reduction of corrosion layers by radio-frequency (RF) low pressure hydrogen plasma. Chosen barrier films are parylene (poly-para-xylylene) coatings and SiO2- like high density films. Parylene coatings are prepared by a standard chemical vapor deposition (CVD) method. Plasma enhanced chemical vapour deposition (PECVD) enables preparation of SiOx based thin films with higher flexibility due to variable incorporated organics groups. The coatings were characterized by various methods in order to obtain information about their chemical structure (FTIR) and barrier properties (OTR). The results from standard corrosion test were compared with those on samples treated by conventional conservation procedures.

Plasma treatment of metallic artefacts

Summary form only given. The traditional process of preservation of artefacts is a long term procedure. Ageing destroys untreated artefacts and we lose our cultural heritage. This study focuses on alternative way how to save the artefacts before their destruction.