The KPR 200 mm plasma reactor is a device designed for the surface modification of various materials. Such a modification occurs by applying a unique type of plasma – plasma generated on a ceramic dielectric. The ceramic dielectric is a durable system with which it is possible to continuously modify the surfaces of materials with such a plasma. The advantage of applying this unique type of plasma is that the modification of the materials occurs at room temperature and atmosphere. However, it is necessary to monitor and observe certain parameters, for example: the selected power, the exposure time of the surfaces of the modified materials, and the distance of the surface from the ceramic dielectric itself. Therefore, in the present paper, the effect of diffuse coplanar surface barrier discharge (DCSBD) plasma discharge on selected polymeric materials was investigated. Plasma impact assessment was also performed using image analysis, that could provide relevant information in the process of plasma‐chemical modification. Changes in the surfaces of the investigated thin polyvynil chloride material, before and after exposure to plasma discharge, were also observed (changes in contact angle, atomic force microscopy).
Polymeric surfactants were prepared from two beechwood glucuronoxylans, differing in the uronic acid content, molecular mass and solubility, by transesterification with vinyl laurate under homogeneous and heterogeneous reaction conditions and with methyl laurate under solvent-free conditions. The water-soluble derivatives exhibit significant emulsifying efficiency comparable to that of the commercial surfactants Tween 20 and Slovasol 245. The performance tests indicated good washing power and very low antiredeposition efficiency. Water-soluble glucuronoxylan laurates can be prepared from both xylan preparations with non-toxic esterification agents as well as under “solventfree” reaction conditions.
The textile materials can be used in many technical applications in various fields, such as automotive. Depending on the application areas, the textile or fiber‐based materials have to meet certain predetermined requirements. Textile yarns can be used as reinforcing cords in composites in which an elastomeric matrix is used. The basic mechanical tensile test at standard temperature does not provide all the information required for obtaining the material parameters. The tests are also necessary to be performed at reduced temperatures, depending on the following application. Furthermore, it is necessary to consider stress relaxation in specific tests for the practical use. In this work, there is the experimental investigation of the effect of the selected temperatures (20 °C and 120 °C) and the relaxation times (60 s and 120 s) on the mechanical properties of the selected textile yarns from polyamide 6.6 under the uniaxial tensile tests. The results reveal that the relaxation time for the first 20 seconds is interesting because there is a significant decrease in the force while holding the strain. A final method is proposed, and it can be used for any other applications, and it guarantees the repeatability of measurements in the relatively fast measured time.
This work was focused on studying the properties of epoxy (EP) composite materials reinforced with glass, (GF) carbon (CF) and aramid (AF) fibres. The composites were made by hand lay-up (HL) and vacuum infusion process (VIP) with 8, 10, 12 number of fabric layers. Studied were tensile strength, elongation, flexural stress, flexural strain, thermal stability, texture of surfaces, cuts, fractures of laminates and the thickness of the laminate according to the type and number of layers of fabric and the method of manufacture. Composites made by VIP achieve better mechanical properties than composites made by HL. Tensile strength was highest in composites reinforced with AF. Composite materials reinforced with GF exhibit the lowest values of tensile strength. Flexural strength was significantly the highest in CF reinforced composites followed by the laminates reinforced with GF and AF. The highest values of flexural deformation were measured in composites reinforced with AF and the lowest values of flexural deformation were measured in composites reinforced with CF. By thermogravimetric analysis (TGA) was recorded weight loss of the EP matrix in the range from 290 to 480 °C and AF in range from 530 to 605 °C. By TGA was demonstrated lower content of EP matrix in the composites made by VIP, which was confirmed by comparison of thickness of the studied laminates.
Besides mechanical properties, the dynamic mechanical properties in a sensible range of temperature and rheological properties have to be taken into account for engineering applications. The rising concern towards the reduction in the use of petroleum-based non-renewable resources has led to increasing interests in natural polymer composites filled with natural organic fillers, i. e. they are from renewable and biodegradable sources. This work is focused on the use of biowaste, specifically wood flour as a plasticizer replacement in a rubber compound. Plasticizers (also called softener, extender or process oils) are common additives for polymers with a low molecular weight.An increasing content of a plasticizer usually leads to a decrease in the viscosity of the rubber mixture, and therefore, its processability can be improved.Based on the given fact, the experiment is aimed at the studies of the rheological properties. The scanning electron microscopy results can confirm the compatibility or incompatibility of the biowaste, specifically wood flour with rubber matrix. In the case of a successful replacement for plasticizer with wood flour, we expect a significant reduction in the cost of the mixtures production as well as a reduction in the environmental impact, compared with the petroleum products.
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