Pavla Ryparová

Nanofibrous poly(lactide-co-glycolide) membranes loaded with diamond nanoparticles as promising substrates for bone tissue engineering.

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Influence of surface modification of wood with octadecyltrichlorosilane on its dimensional stability and resistance against Coniophora puteana and molds

A relatively new approach for wood protection against fungal decay is based on hydrophobization of wood and on lowering its moisture content. Water repellence of wood can be increased by polymerization of hydrophobic monomers in wood cell walls. It was found that Norway spruce wood after treatment with octadecyltrichlorosilane exhibited reduced water uptake by the wood cell walls, lowered water vapour sorption, and significantly increased dimensional stability of wood in terms of anti-swelling efficiency. Hydrophobicity and lower equilibrium moisture content were shown to cause increased resistance of the treated samples against brown-rot decay and molds.

Coating of wood by means of electrospun nanofibers based on PVA/SiO2 and its hydrophobization with octadecyltrichlorosilane (OTS)

Abstract Poly(vinyl) alcohol (PVA)/nanosilica (SiO2) based electrospun nanofibers has been deposited on wood substrate by means of the roll electrospinning process. The nanofibrous coating was hydrophobized by self-assembled monolayers of octadecyltrichlorosilane (OTS) via a sol-gel dipping process. The PVA/SiO2 nanofiber coating and OTS hydrophobized coating were characterized by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and energy dispersive X-ray analysis (EDXA). All methods confirmed the formation of OTS monolayers on hybrid coatings. The adhesive strength and resistance to scratch of nanofibers coating was also evaluated.

Mechanical Properties of Single and Double-Layered PVA Nanofibers

Multi-layered nanofiber textiles can be utilized in many applications. In such case the individual layers are laid in more stages and the question arises whether the connection is perfect. Two kinds of samples of PVA nanotextiles having the weight of 1.3 g/m2 (single-layered, AI) and 2.8 g/m2 (double-layered, AII), respectively. It was shown that mechanical properties, in particular the average tensile strength (24 N/mm for AI and 51 N/mm for AII) and stiffness (950 N/mm for AI and 1600 N/mm for AII), are independent of the number of layers, only their weight per unit area matters. This indicates that the bond between the individual layers is perfect.

PROTECTION OF WOODEN MATERIALS AGAINST BIOLOGICAL ATTACK BY USING NANOTECHNOLOGY

This article is focused on protection of wooden materials by using nanofibrous textiles with biocidal addition, which continues on the work of a group at the Center for Nanotechnology at the Faculty of Civil Engineering in the CTU. Timber is a natural material which is predisposed for biodegradation and therefore it is essential to study suitable and effective protection against microorganisms. Wood is a material susceptible to biological corrosion and therefore it is necessary to protect it. The study compares biocidal efficiency of polymer solution as a coating and as a layer from nanofiber textiles. We used polyvinyl alcohol (PVA) as a basic polymer which was enriched by substances from commercial Lignofix E – profi, solution of CuSO 4 · 5H 2 O and AgNO 3 and finally colloidal silver as an example of nanoparticles. The final concentration of the biocidal substance was 1 (v/wt)% in fiber. The nanofiber textiles are produced on the device Nanospider NS LAB 500 (Elmarco, CR) on cylinder rotating electrode. The study was divided into two parts, the first being an agar plate test and the second a test on samples from timber. The mixture of mold was used as the model organism. ( Alternaria tenuissima, Pochonia bulbiosa, Trichoderma viride and Acremonium sclerotigenum ). Comparison of efficiency between the polymer paint and nanofiber textiles showed no difference. The best results were shown by PVA with an addition of substances from the commercial biocidal treatment Lignofix-E Profi on the agar plate. The difference of result was shown on timbre samples, finding that the best results were with treatment by PVA doped by Silver nitrate. The anticipated results were shown by treatment with non-doped PVA, which does not have any fungicidal protective effect.

Influence of Copper Ions on Mechanical Properties of PVA-Based Nanofiber Textiles

The nanofiber textiles are utilized in the textile industry, as a treatment of exposed surfaces, they find their use in medicine and in future they might be used in civil engineering as vapor barriers. For some applications it is advantageous to use the textiles with special, e.g. antibacterial, treatment by means of silver or copper ions. This paper is focused on the determination of mechanical properties of PVA-based nanofiber textiles produced by electro-spinning. The polymer solution used for electrospinning contained copper in the form of ions. The results of the tensile testing were compared with the results for the reference sample without any additives. The results indicate that the addition copper ions cause an increase of the strength and stiffness.

Resistance of bamboo scrimber against white-rot and brown-rot fungi

ABSTRACT Bamboo scrimber is one of the most emerging structural materials for future building applications and it possesses properties comparable to other natural wood-based engineered materials such as glulam, laminated veneer lumber and cross-laminated timber. The goal of this work was to study the decay resistance of bamboo scrimber against white-rot (Trametes versicolor) and brown-rot fungi (Serpula lacrymans). Bamboo scrimber samples were incubated in petri dishes with the wood-decaying fungi and the weight loss after 12 weeks was measured. The surface morphology of fungal-degraded bamboo scrimber was evaluated using optical microscopy. Based on the percentage weight loss, bamboo scrimber could be classified as highly resistant against bio-deterioration by white and brown-rot fungi.

Methodology for Determination of the Requirement of Repair of External Facades of ETICS due to the Occurrence of Microorganisms

The submitted article deals with a relatively new phenomenon, which is monitoring and solution to minimization of microorganisms ́ occurrence on the surface of the External Thermal Insulation Composite Systems (ETICS). The importance of the solution has been becoming more important both from the point of view of health risk for inhabitants and accelerated degradation of particular layers of the ETICS due to the presence of these microorganisms. The article submits conceptual methodological solution to the reduction of count of microorganisms on the ETICS surface from diagnosis, setting out criteria for the necessity of determination of macrobiotic biodeteriogens to subsequent rehabilitation design.

The Efficiency of PVA Based Nanofiber Textile PVA Doped Silver Particles against Mold

Mold and algae are primitive organisms that cause biological degradation of many type of construction materials. Subsequent remediation of damaged structures is very demanding and it is therefore necessary to take into consideration the high preventive protection against these microorganisms. In practice, as the prevention it is often use chemical products as a classical biocidal compounds. One of the modern methods of protection investigate the use of nanotechnology with biocidal ingredients, which is the main topic of this article. Silver ions and silver nanoparticles were selected as a biocide for the experiment. Research revealed that the silver in the form of nanoparticles and ions have biocidal effect against fungi and algae and it is conform to use theoretically possible them as a preventive protection against mold and algae.

The Dependence of Mold on the Relative Humidity in Different Types of Materials

Building materials commonly used in Central Europe across the material base tend to have problems with the occurrence of mold. This is not only an aesthetic issue, but attacked material loses its properties as strength and durability and there is also a deteriorationening in other properties. This paper is focused on the susceptibility of wood and gypsum based materials to the development of mold at different humidity. There were also studied mold species occurred in samples naturally. Significantly increased the growth of mold on the surface was observed with samples placed into 98 % relative humidity than samples at 80 % relative humidity. Predominant mold was found on the surface of samples of solid wood. The most observed species was Trichoderma viride on wood based materials.