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EN
The melt-mixing method was used to obtain nanocomposites of poly(ethylene-co-vinyl acetate) (EVA) with 1, 3 or 5 wt% of hydrophilic zinc oxide (ZnO) nanoparticles. The contact angle, barrier and antimicrobial properties of the obtained composites were investigated. The nanocomposites were characterized by better hydrophilic and barrier properties, as evidenced by, respectively, a smaller contact angle and lower water vapor permeability and water absorption compared to EVA, which can be explained by the formation of hydrogen bonds between EVA and ZnO. In addition, the composites were characterized by greater bactericidal activity against E. coli and S. aureus. The optimal physical and microbial properties were obtained with 3 wt% ZnO content.
PL
Metodą mieszania w stanie stopionym otrzymano nanokompozyty kopolimeru etylen-octan winylu (EVA) z dodatkiem 1, 3 lub 5% mas. hydrofilowych nanocząstek tlenku cynku (ZnO). Zbadano kąt zwilżania, właściwości barierowe i przeciwdrobnoustrojowe otrzymanych kompozytów. Nanokompozyty charakteryzowały się lepszymi właściwości hydrofilowymi i barierowymi, o czym świadczy, odpowiednio, mniejszy kąt zwilżania oraz mniejsza przepuszczalność pary wodnej i absorp¬cja wody w porównaniu z EVA, co można wyjaśnić tworzeniem się wiązań wodorowych pomiędzy EVA i ZnO. Ponadto kompozyty miały większą aktywność bakteriobójczą wobec E. coli i S. aureus. Optymalny zespół właściwości uzyskano przy 3% mas. zawartości ZnO.
2
Content available remote Multifunctional Finishing of Cotton Fabric
EN
The research in textiles is being driven by ecology, economy, and functionality. Therefore, the present research is focused on the development of multifunctional textiles that consume minimum energy during their processing, eco-friendly chemicals for functionalization, and use short processing steps. Eco-friendly cross-linkers such as butanetetracarboxylic acid and zinc oxide nanoparticles are used to impart wrinkle recovery, antibacterial activity, ultraviolet (UV) protection, bending rigidity, and antistatic properties to cotton fabric just in one step. The treated fabric has been characterized with Fourier-transform infrared spectrophotometer, scanning electron microscope, and X-ray diffractometer. Wrinkle recovery, tear strength, antibacterial activity, UV protection, and antistatic properties were tested with AATCC 66-1990, ASTM D 1224, AATCC 147, AATCC 183, and UNI EN 1149, respectively. The treated fabric shows excellent functional properties up to 20 washing cycles.
3
Content available remote Optical properties of PVP/ZnO composite thin films
EN
Purpose: The aim of the work was the preparation of thin composite layers from PVP polymer doped by ZnO nanoparticles using the spin coating method and the analysis of the applied reinforcing phase on the morphology and optical properties of obtained composites. Design/methodology/approach: To analyse the morphology of thin coatings a technique of surface topography imaging using the atomic force microscopy (AFM) was applied. Analysis of the optical properties was conducted using absorbance spectrum in function of wavelength for all produced thin coatings using UV-Vis spectroscopy. Findings: AFM results show that mass concentration of ZnO nanoparticles of 10% in a solution of PVP/EtOH polymers has a meaningful influence on the morphology of the surface of the PVP/ZnO composite coatings. Using obtained absorbance spectra, the width of the band gap of the manufactured composite coatings were determined which were compared with a band gap values of pure polymer and used reinforcing phase. Practical implications: The analysis of the values of the energy band gap of the manufactured materials showed that both for pure polymer and composite coatings values of energy band gap are similar approx. 4 eV at the same time decrease the degree of absorption of electromagnetic radiation caused by the increasing concentration of the reinforcing phase, which indicates the broad possibilities of application of this type of the material.
EN
Experimental investigation was conducted on the thermal performance and pressure drop of a convective cooling loop working with ZnO aqueous nanofluids. The loop was used to cool a flat heater connected to an AC autotransformer. Influence of different operating parameters, such as fluid flow rate and mass concentration of nanofluid on surface temperature of heater, pressure drop, friction factor and overall heat transfer coefficient was investigated and briefly discussed. Results of this study showed that, despite a penalty for pressure drop, ZnO/water nanofluid was a promising coolant for cooling the micro-electronic devices and chipsets. It was also found that there is an optimum for concentration of nanofluid so that the heat transfer coefficient is maximum, which was wt. % = 0.3 for ZnO/water used in this research. In addition, presence of nanoparticles enhanced the friction factor and pressure drop as well; however, it is not very significant in comparison with those of registered for the base fluid.
EN
The paper presents a method for obtaining nanoparticles of ZnO by thermal decomposition of the Zn-containing compounds. The experiment was based on the thermal decomposition of basic zinc carbonate to zinc oxide (with a content of 58-61 wt.%). Basic zinc carbonate was analysed by derivatography and then annealed at a selected temperature (about 600ºC) for about 1 h. Products of thermal decomposition of the compound were studied by XRD analysis and SEM scanning microscopy.
PL
W pracy zaprezentowano metodę otrzymywania nanocząstek ZnO na drodze termicznego rozkładu związków zawierających Zn. W eksperymencie wykorzystano termiczny rozkład zasadowego węglanu tlenku cynku (o zawartości od 58-61% mas.). Zasadowy węglan cynku poddano analizie derywatograficznej a następnie wygrzewaniu w określonej temperaturze (ok. 600ºC przez ok. 1 godz.). Produkty termicznego rozkładu związku badano analizą XRD oraz mikroskopia skaningowa SEM.
EN
Studies of the effect of the kind of alcohol, electrolyte concentration and water on the anodic dissolution of zinc and the nature of dissolution products were performed. The dissolution products were analyzed by spectroscopic methods (SEM/EDS, XPS and UV-vis) and X-ray diffraction. These studies have shown that the process of anodic dissolution of zinc in alcohol electrolytes (methanol and ethanol) in the presence of water (1-5% vol.), is a simple way to obtain ZnO nanoparticles.
PL
Przeprowadzono badania wpływu rodzaju alkoholu, stężenia elektrolitu oraz zawartości wody na proces anodowego roztwarzania cynku i charakter tworzących się produktów roztwarzania w obszarze wysokich potencjałów. Do identyfikacji produktów anodowego roztwarzania wykorzystano spektroskopowe techniki badawcze (SEM/EDS, XPS, UV-vis) oraz metodę dyfrakcji rentgenowskiej. Badania te wykazały że proces anodowego roztwarzania cynku w alkoholowych elektrolitach (metanolowych i etanolowych) w obecności wody (1-5% obj.), jest prostym sposobem otrzymywania nanocząstek ZnO.
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