Investigation of the changes in physical properties of PES/PVC fabrics after aging

The aim of this work was to investigate the physical and mechanical performance of architectural polyester (PES)–poly(vinyl chloride) (PVC) membranes exposed to different artificial aging conditions. Two commercially available architectural membranes were chosen as research objects. The durability of the PES/PVC fabrics was evaluated by the loss in mechanical performance, scanning electron microscopy, and X-ray diffraction analysis in order to understand the effect of the degradation agents on the surface of the membranes. The mechanical performance of the PES/PVC membranes was unchanged. Scanning electron microscopy images of the tested materials showed initial cracks after aging. The X-ray fluorescence analysis showed that at the time of aging, the amount of Cl and Si decreased slightly, while Ti decreased by half, and Ca by volume increased twice. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47523.     

Analysis of knitted fabrics deformations non-uniformity

The article presents the tensile forces caused knitted fabrics’ deformations non-uniformity analysis. At first, the tensile behaviour was analysed by applying new method based on specific Y-shaped and stretching specimen. This shape of specimen allows to fulfil wearing conditions of apparel made of knitted fabrics. After this, the article analyses research conditions and knitted fabrics’ deformability physical characteristics and determines longitudinal, transverse and angular deformations. The deformations properties were evaluated using graphic and numerical methods. Investigations have shown that elastane fibres significantly influenced fabric deformability, dimensional changes and deformations’ non-uniformity. Experiments have also shown that Y-shaped specimen tensile test is a simple, universal and reliable method suitable to obtain quantitative information about textile materials deformability.     

Functionalization of Fluorinated Benzenesulfonamides and Their Inhibitory Properties toward Carbonic Anhydrases

Substituted tri‐ and tetrafluorobenzenesulfonamides were designed, synthesized, and evaluated as high‐affinity and isoform‐selective carbonic anhydrase (CA) inhibitors. Their binding affinities for recombinant human CA I, II, VA, VI, VII, XII, and XIII catalytic domains were determined by fluorescent thermal shift assay, isothermal titration calorimetry, and a stopped‐flow CO₂ hydration assay. Variation of the substituents at the 2‐, 3‐, and 4‐positions yielded compounds with a broad range of binding affinities and isoform selectivities. Several 2,4‐substituted‐3,5,6‐trifluorobenzenesulfonamides were effective CA XIII inhibitors with high selectivity over off‐target CA I and CA II. 3,4‐Disubstituted‐2,5,6‐trifluorobenzenesulfonamides bound CAs with higher affinity than 2,4‐disubstituted‐3,5,6‐trifluorobenzenesulfonamides. Many such fluorinated benzenesulfonamides were found to be nanomolar inhibitors of CA II, CA VII, tumor‐associated CA IX and CA XII, and CA XIII. X‐ray crystal structures of inhibitors bound in the active sites of several CA isoforms provide structure–activity relationship information for inhibitor binding affinities and selectivity.     

Recent progress in understanding the persistent luminescence in SrAl2O4:Eu,Dy

Ever since the discovery of SrAl₂O₄:Eu,Dy persistent afterglow material, that can intensively glow up to 20?h, the mechanism of long-lasting luminescence has been a popular area of research. The research is focused on discovering the mechanism of persistent luminescence in order to prolong the duration and intensity of afterglow in a controlled way. Although most researchers agree on the general things, there are still many unclarities and ambiguities to discuss upon. This review paper briefly sketches in the highlights of past research on the luminescence mechanism in SrAl₂O₄:Eu,Dy, mainly focusing on the research conducted in the past decade dedicated to clearing these ambiguities. This paper provides an overview of the latest persistent luminescence mechanisms offered by researchers.     

Properties of recycled polycaprolactone‐based thermoplastic polyurethane filled with montmorillonites

The properties of recycled low temperature biodegradable polycaprolactone‐based thermoplastic polyurethane (rTPU), filled with different types of organically modified montmorillonite (MMT) prepared by two‐roll milling, were studied. The dependence of rTPU properties on the mastication time and clays content was determined by various structural and physical testing methods. Results show that the melt flow and mechanical properties of rTPU deteriorate with increasing of mastication time, but thermal properties were affected only slightly. rTPU/MMT composites show exfoliated or intercalated structures depending on the nature of organic modifier of clay. MMT reduces slightly rTPU tensile and melt flow properties, but accelerates hydrolytic degradation process. During degradation the weight loss and polydispersity increase significantly in the presence of MMT, but it does not accelerate crystallinity changes. The degradation of rTPU composites with higher hydrophilicity organoclays proceeds faster than that with hydrophobic ones due to the relatively higher interaction with polymer matrix. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Photoelectrochemical phenomena at the interface Cu/Cu(II), glycine, α- or β-alanine

The analysis of photopotentials and photocurrents induced by laser beam perturbation of the interface Cu/solution of Cu(II)—glucine, α- or β-alanine complexes, has shown that phase layers containing Cu₂O display the properties of p-type semiconductors, except for the β-alanine system which displays n-type conductivity. In accordance with results of the analysis of thermodynamic and kinetic stability of Cu₂O layers the highest level of photoresponse is observed in the β-alanine system. Inversion of the photocurrent sign has been registered in the latter system at a certain cathodic overvoltage, the value of which depends on both the pH of solution and the laser emission intensity.     

The evaluation of the uncertainty of the research method on the geometrical parameters of the embroidery elements

The indirect measurement method of the contour width deformation of the embroidery element is presented in the work. The square-shaped, directly measured, embroidery element is compared to its digital image. Together with the used test methods steps, the reliability criteria for this method are presented as well. The reliability of the method of measuring the geometrical parameters of a closed contour element of an embroidered square shape is evaluated by analyzing its systematic and random errors and by calculating the total standard uncertainty. In assessing the accuracy of the measurement method, there is also a talk about a comprehensive assessment of measurement uncertainty. Measurement uncertainties are considered to be one of the most important parameters of the ability of a method to determine the possibilities of using and applying the method. When measuring the parameters of real samples, the components of total uncertainty related to the characteristics of the specimen (weave, surface density, filling characteristics, direction of the fabric yarn), their variation within certain limits and possible correlation among these components, influence of the standard means, data processing, digital image calibration were evaluated. It has been determined during the research that a negative error ～2.4% with expanded uncertainty ～3.3% complying with the requirements of the reliability of the method is typical for the deformation measurement method applied for the measurement of the five (6, 10, 14, 18, and 22?mm) elements of different contour widths. Because of that the evaluation of the uncertainty according its components is useful while analyzing the factors which have an impact on the deformation.     

Investigation of electrospun web porosity and its statistical evaluation

Abstract

In order to objectively study the influence of various factors on the structure and porosity of the electrospun nanofibers webs and to compare the results obtained by different authors, an objective method of porosity evaluation is needed. Analysis of literature has shown that the lack of a common method for evaluating the structure of electrospun webs generates uneven results. The method of electrospun web porosity evaluation by maximum pore size in the web is presented in this article. The main investigations were done with polyamide 6 electrospun nanofibrous web. It was stated that distribution of maximum pore size in various places of the web is close to Gausian normal distribution with some positively skew. This skew is the reason why classical statistical methods cannot be used for electrospun web porosity evaluation. It was stated that for maximum pore size evaluation with reliability 99.9%, it is not possible to use 4S (4 standard deviation) rule. In the case of 100 measurements, it is necessary to use 5S rule, and in the case of 20 or 10 measurements – even 7S or 8S rule, respectively. The results show that for maximum possible pore size evaluation, it is necessary to have much more than 10 or 20 measurements (photos), and for obtaining the same reliability, it is necessary to use a higher coefficient with standard deviation, as in the classical statistical case of Gausian distribution.