Sandra Bischof Vukušić

Polycarboxylic acids as non-formaldehyde anti-swelling agents for wood

Abstract Wood specimens of fir (Abies alba Mill) and beech (Fagus sylvatica L.) were chemically modified using polycarboxylic acids (PCA), cured by convection heating or microwave treatment and analyzed by HPLC. A new non-formaldehyde cross-linking system was composed of citric acid (CA) and 1,2,3,4-butanetetracarboxylic acid (BTCA), which are representative polycarboxylic acids (PCAs). These reagents require phosphono-based catalysts, so a sodium hypophosphite (SHP) catalyst was used in this study. The effects of PCA treatment were compared with a previously introduced 1,3-dimethylol 4,5-dihydroxy ethylene urea (DMDHEU) treatment. The dimensional stability of the modified wood was determined in terms of the anti-swelling efficiency (ASE) using the water soak/oven dry method. The results revealed an improvement in ASE for wood modified with PCA compared to modification with DMDHEU. Qualitative and quantitative determinations of bound acids were performed by HPLC. Further intensification of the wood modification process and an increase in the quality of wood-based materials were achieved using microwave treatment. Among other benefits, the formation of cross-links between the wood and the reagent components led to an improvement in the tensile strength retention, particularly in combination with the microwave treatment.

Cotton textiles modified with citric acid as efficient anti-bacterial agent for prevention of nosocomial infections

Aim To study the antimicrobial activity of citric acid (CA) and sodium hypophosphite monohydrate (SHP) against gram-positive and gram-negative bacteria, and to determine the influence of conventional and microwave thermal treatments on the effectiveness of antimicrobial treatment of cotton textiles. Method Textile material was impregnated with CA and SHP solution and thermally treated by either conventional or microwave drying/curing treatment. Antibacterial effectiveness was tested according to the ISO 20743:2009 standard, using absorption method. The surfaces were morphologically observed by scanning electron microscopy, while physical characteristics were determined by wrinkle recovery angles method (DIN 53 891), tensile strength (DIN 53 837), and whiteness degree method (AATCC 110-2000). Results Cotton fabric treated with CA and SHP showed significant antibacterial activity against MRSA (6.38 log10 treated by conventional drying and 6.46 log10 treated by microwave drying before washing, and 6.90 log10 and 7.86 log10, respectively, after 1 cycle of home domestic laundering washing [HDLW]). Antibacterial activity was also remarkable against S. aureus (4.25 log10 by conventional drying, 4.58 log10 by microwave drying) and against P. aeruginosa (1.93 log10 by conventional and 4.66 log10 by microwave drying). Antibacterial activity against P. aeruginosa was higher in samples subjected to microwave drying/curing than in those subjected to conventional drying/curing. As expected, antibacterial activity was reduced after 10 HDLW cycles but the compound was still effective. The surface of the untreated cotton polymer was smooth, while minor erosion stripes appeared on the surfaces treated with antimicrobial agent, and long and deep stripes were found on the surface of the washed sample. Conclusion CA can be used both for the disposable (non-durable) materials (gowns, masks, and cuffs for blood pressure measurement) and the materials that require durability to laundering. The current protocols and initiatives in infection control could be improved by the use of antimicrobial agents applied on cotton carbohydrate polymer.

Study of antimicrobial properties of cotton medical textiles treated with citric acid and dried/cured by microwaves

The purpose of this study was to examine antibacterial and antifungal activity of antibacterial finish based on Citric acid on cotton medical textiles. The ability to effectively reduce the number of gram-negative, gram-positive bacteria and yeast was evaluated, specifically comparing the antibacterial activity after two different drying/curing methods. Citric acid (CA) and diethyl–tetradecyl–[3–(trimethoxysilyl)-propyl] ammonium chloride (Quat) were used for hygiene and disinfection purposes of medical textiles in this study. It was applied by pad-dry process and its fixation to cellulose hydroxyls was enhanced either by high curing temperatures or microwaves (MW). Determination of antibacterial activity of finished products was performed according to ISO 20743:2007 standard before the washing and after the 10 washing cycles. Antibacterial activity was tested against gram-negative bacteria, Escherichia coli, gram-positive-Staphylococcus aureus and yeast, Candida albicans. Obtained results are confirming the possibility of eco-friendly CA application, for the purpose of antimicrobial finishing of cotton medical textiles. Prevention of nosocomial infections with the Citric acid is possible using both curing methods (convection and microwave) and furthermore, the treatment is durable up to 10 washing cycles. Citric acid, as one of the suitable active substances is crosslinked to the cellulose hydroxyls by the formation of ester linkages. Its antimicrobial effectiveness against the chosen microorganisms proved to be the best against S. aureus. Applied finish bath has additional crease proof effectiveness providing sufficient both antimicrobial and crease proof effectiveness, so as the durability against 10 washing cycles.

Influence of Microwaves on Nonformaldehyde DP Finished Dyed Cotton Fabrics

An alternative approach to formaldehyde-releasing conventional N-methylol com pounds is based on the use of nonformaldehyde durable press polycarboxlic acid (PCA) finishing agents. Another alternative approach, investigated here, is using microwave energy to impart durable crease resistance to dyed cotton fabric. The bifunctional dyes C.I. Reactive Red 195, C.I. Reactive Yellow 145, and C.I. Reactive Blue 221 are used in the study, and the isocratic HPLC method is employed to quantify the PCA reacted with the cellulosic material for two different curing procedures. Shade change evaluation reveals that microwave curing has a greater influence on the dE values than conventional curing. In all other aspects, primarily wrinkle recovery and deformation resistance, microwave curing offers much better results.

Comparison of Spanish broom (Spartium junceum L.) and flax (Linum usitatissimum) fibre

After a long break, Spanish broom gained interest as a natural, sustainable and renewable fibre for textile and technical applications. This paper describes the characterization of Spanish broom fibres (Spartium junceum L.) in comparison to the flax fibres (Linum usitatissimum). Spanish broom fibres were obtained by two different methods of maceration and some of the most significant chemical and physical properties of tested fibres are reported. Scanning electron microscopy has proven to be a useful tool for the determination of morphological characteristics of elementary and technical fibres. Other physical-chemical properties of fibres were determined by infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), fineness and tensile strength methods.

The Effect of Microwave Drying on Warp Sizing

The paper describes our research of microwave usage in drying the size pick-up. An analysis of three different drying processes in relation to physical-mechanical properties of sized yarn has been carried out. Under the same sizing conditions, but different drying methods, the following parameters were determined: breaking force, elongation at break, abrasion resistance and yarn hairiness. The application of microwave drying method for warp sizing showed to be equally good, or even better in some cases, compared to the conduct and convection drying methods.

Microwaves in Chemical Finishing of Textiles

The esterification involved in durable press (DP) finishing is one among several chemical reactions that can be improved by microwave radiation. Cotton material is usually esterified with modified 1,3 dimethylol 4,5 dihydroxyethylene urea (DMDHEU). In this study, a novel microwave planar device was used for simultaneous drying and curing processes. The device was constructed at the Department of Textile Chemistry and Material Testing of Faculty of Textile Technology and it is based on a magnetron-fed travelling wave applicator with meandered waveguide. The experimental results showed that microwave-assisted textile finishing yields better results than conventional curing at tenter frame. Noticeable improvements were obtained in wrinkle recovery resistance and tensile strength reduction. In addition, the influence of microwaves on formaldehyde release was investigated in order to decrease formaldehyde emission from textile material. Several different experimental methods were used in order to identify a mechanism of formaldehyde release

SEM Characterisation of the Cellulose Material Treated with Polycarboxylic Acid and Zeolite Nanoparticles

Coating of zeolite nanoparticles, previously dispersed in Polycarboxylic acid (PCA) solution, on cellulose textile surface has several advanced technological applications. One of the possible usages is for the Durable Press finishing enabling simultaneous enhanced antimicrobial or flame retardant properties. In this study, one of the polycarboxylic acid crosslinking agents, Citric acid (CA) is used to coat cotton fabric in the presence of synthesized zeolite applied as a catalyst. Cotton fabric samples were padded with a suspension containing zeolite powder in aqueous solution of CA crosslinking agent. Drying and curing of coated samples was performed at different curing conditions, either in a microwave oven or in conventional dryer. Scanning electron microscope (SEM) is used to characterize the surface morphology and confirm bonding of zeolite particles to cellulose fibers. Further characterization of coated surface is performed by attenuated total reflectance (ATR) Fourier transform infrared (FT-IR) spectroscopy while the effects of microwave irradiation on zeolite nanoparticles bonding is estimated by thermogravimetric analysis.