Vili Bukošek

Functionalization of PET fabrics by corona and nano silver

In this work, the antibacterial and other properties of polyester fabrics previously functionalized by corona and/or silver nano particles have been studied. Corona air plasma was used as a pretreatment of raw, washed and washed-thermostabilized polyester fabrics to increase the adhesion of nano silver particles resulting in an excellent antibacterial effect. X-ray photoelectron spectroscopy was applied to analyze the surface composition and chemical bonding of the surface atoms on untreated and treated fabrics. The surface morphological changes of polyester fibers were observed by scanning electron microscopy (SEM). The quantity of silver on the polyester fabrics was determined by the use of the inductively coupled plasma-atomic emission spectrometry method. The antimicrobial properties of functionalized polyester fabrics were tested according to American Society for Testing and Materials ASTM Designation: E 2149-01. Additionally, the dyeing of polyester fabrics with selected disperse dye as well as capillary action tests were performed to confirm the chemical and morphological changes of polyester fibers after corona treatment. Considerable differences in surface composition were found between the raw and washed or washed-thermostabilized fabrics. The surface of raw fabrics is richer in carbon and the concentrations of the C—O and O—C=O groups are lower than on the other samples. An opposite effect is observed for washed and washed thermostabilized fabrics. SEM analyses show that the plasma treatment also affects the surface morphology. The chemical surface composition and morphology are highly related to the hydrophobicity and hydrophylicity, and the achievement of better nano silver adhesion and enhanced dyeing and antimicrobial properties of differently prepared corona plasma-treated polyester fabrics. Therefore, corona air-treated raw polyester fabrics demonstrated optimum antimicrobial properties due to the excellent adhesion of nano silver.

CF4 plasma and silver functionalized cotton

In an attempt to use minimal concentrations, initially, of silver nanoparticles for loading onto textiles and to achieve maximum concentrations on the material, CF4 low-pressure plasma was used on bleached and mercerized cotton fabric. The concentrations of silver on the fabrics were determined by the ICP-MS method (inductively coupled plasma-mass spectrometry), the morphology of fiber surfaces was observed with a scanning electron microscope (SEM), and an x-ray photoelectron spectroscopy (XPS) study was used for the evaluation of surface chemical changes. The antibacterial effect of silver loaded fabrics was tested against Enterococcus faecalis and Pseudomonas aeruginosa. The best results were found for plasma-treated cotton fabric functionalized with 30 nm silver particles. The results show effective plasma etching of the fabric surface, which caused excellent adhesion of silver particles. Color measurements of dyed samples showed that CF 4 plasma does not affect the color of dyed cotton. The mechanical properties of cotton remain unaltered after plasma treatment.

Functionalization of Polyester Fabric by Ar/N2 Plasma and Silver

The objective of this research was to use Ar/N2 (50%:50%) plasma to increase the adhesion of nano silver particles to raw polyester fabric. RUCO-BAC AGP was applied using the exhaust method. X-ray photoelectron spectroscopy revealed differences in surface composition between the Ar/N2 plasma-treated and untreated raw fabrics. The Ar/N2 plasma treatment was found to increase the surface carbon concentration and decrease the concentration of C-O and O-C=O groups on the surface. After plasma etching, the specific surface of the polyester fabric and properties related to it were found to change significantly. This change was confirmed by a decrease in the whiteness index and an increase in the dyeability of the polyester fabric with disperse dye. Morphological changes in the surface of plasma-treated polyester fabric enabled greater adhesion of nano silver particles and increased the antimicrobial effect with respect to Pseudomonas aeruginosa, Escherichia coli and Streptococcus faecalis.

The Influence of Water Vapor Plasma Treatment on Specific Properties of Bleached and Mercerized Cotton Fabric

The influence of water vapor plasma on chemical, morphological and mechanical properties of bleached and mercerized cotton fabric was studied. Reactive exhaust dyeing was used for loading of nano silver. Inductively coupled plasma mass spectroscopy results show that plasma treatment enhanced nano silver adhesion to the fabric, which also contributed to antimicrobial effectiveness to Pseudomonas aeruginosa and Escherichia coli. Surface changes of plasma treated cotton were observed with scanning electron microscopy. Xray photoelectron spectroscopy results show the decrease of C—C bonds in favor of C—O, O—C—O, C=O, and O=C—O bonds and higher O/C atomic ratio in plasma treated fibers. Mechanical properties of cotton yarn after plasma treatment remained unchanged.

A study of the relaxation phenomena in the fabrics containing elastane yarns

Purpose – In this paper, special attention is focused on the study of the relaxation phenomena of fabrics containing elastane yarn.Design/methodology/approach – For this purpose, the relaxation phenomena of wound fabric under constant deformation, as the consequence of accumulated stress during winding, were analysed. Maxwells model and the modified standard linear solid model are used for explaining the relaxation.Findings – The results of the study of the relaxation phenomena of fabrics containing elastane yarn show a close connection between stress relaxation under constant deformation in the fabric roll and the degree of deformation with manual unwinding. Expert knowledge of the relaxation phenomena in fabrics containing elastane yarns has a big influence on explaining the problem of dimensional changes and instability in such fabrics.Originality/value – A better understanding of the relaxation phenomena in fabrics containing elastane yarns.

Surface texture and percolation effects in microporous oriented films of polyolefins

The surface structure of polypropylene and polyethylene microporous films prepared by the extrusion of the polymer melt with the subsequent stages of annealing, uniaxial extension, and thermal fixation of the samples has been analyzed using scanning electron microscopy. It has been shown that percolation through pores corresponds to the axial texture of the surface with the channel structure described by the fractal cluster model. The transition from open pores (through-flow channels) to closed pores leads to the formation of surface regions with a biaxial texture. An increase in the density of the solid phase cluster is accompanied by the formation of a homogeneous biaxial texture with a period of alternation of the density in two mutually perpendicular directions, one of which coincides with the direction of orientation of the films.

Superlattices of lamellae in microporous oriented polyolefine films

The structure and mechanism of the formation of superlattices lamellae in microporous polyolefine (polyethylene and polypropylene) films obtained by polymer melt extrusion followed by annealing, uniaxial extension, and thermal fixation stages have been studied by scanning electron and atomic-force microscopy. It has been shown that oriented anisometric particles, i.e., lamellae aggregates, are formed in films as the spin draw ratio λf increases. At the stage of uniaxial extension (pore formation) of annealed films, a particle ensemble transforms to spatial superlattices of lamellae. Numerical processing of electron microscopy images of the film surface show that the nonmonotonic dependences of the correlation length of density fluctuations and the ratios of the alternation period of particles along extension to their thickness on the parameter λf correspond to a unified mechanism of lamellae ordering.

Disorder-order transition in microporous oriented polyethylene films

Spatial correlations on the surface of microporous polyethylene films obtained by extrusion of the polymer melt with the subsequent stages of annealing, uniaxial extension, and thermal fixation have been studied using scanning electron microscopy. It has been shown that, as the degree of orientation of the melt increases, the formation of the periodic superlattice of oriented lamellae occurs in the films as a result of the disorder-order transition. This transition is preceded by the formation of two mutually complementary percolation clusters, which reflect the pores and the solid phase of the polymer.

Self-organization of lamellae and permeability of microporous oriented polypropylene films

The effect of the annealing temperature Tann of extruded polypropylene films on the structure of membranes prepared by the uniaxial extension of annealed films with the subsequent thermal fixation has been investigated using small-angle X-ray scattering and scanning electron microscopy. It has been shown that an increase in the permeability of membranes with increasing temperature Tann is due to the self-organization of elements of the lamellar structure of the polymer as a result of the ordering and aggregation of particles.

Regularities of lamellae ordering in the formation of polypropylene membrane porous structure

The lamellar structure of porous polypropylene membranes prepared by the extrusion of the polymer melt, annealing of extruded films, and their uniaxial extension has been investigated using data of computer analysis of scanning electron microscopy images. It has been shown that the formation of pores at the stage of uniaxial extension is accompanied by an ordering of lamellae or their self-organization controlled by the annealing temperature Tann. It has been found that the self-organization of lamellae can occur through two mechanisms depending on the spin draw ratio at the stage of extrusion of the polymer melt: in the first case, an increase in the temperature Tann leads to a gradual transition of the disorder-order type; in the second case, a bifurcation transition occurs with a nonmonotonic change in the order parameter. The conditions of the preparation of regular spatial lattices of lamellae have been discussed.