1,720,994 research outputs found
Application of enzymes in wool dyeing
No full textThe application of enzymes in wool dyeing process is an important goal of research in order to reduce the environmental impact and costs of this fundamental finishing process of wool. This work has focused on the possibility of reducing the temperature of conventional dyeing, using an enzymatic pretreatment. Proteolytic enzymes belonging to hydrolase class were used to improve the diffusion of the dye into the fibers at lower temperatures than traditional method, with or without auxiliary agents. Exhaustion curves of the dye bath apparent activation energy values and absorption rate constants were determined. The protection of wool fiber properties during the treatments has been investigated. In order to evaluate a possible fiber damage, the dyed samples were observed by scanning electron microscopy (SEM) and at the same time the loss of tensile strength and elongation were determined. The attack degree of the enzyme was controlled by SDS-Page analysis. In addition, colour fastness to domestic laundering, artificial light, rubbing and perspiration were carried out. These are very
important parameters related to the quality of the material produced. The results of this study show the possibility, thanks to the use of the enzyme investigated, to obtain an homogeneous and strenght dyeing, on fibers maintaining the same mechanical properties, already
working at 85°C, a temperature process clearly under 98°C currently used in industry
Hydrorepellent finishing of cotton fabrics by chemically modified TEOS based nanosol
No full textHydrorepellency was conferred to cotton fabrics by an hybrid organic-inorganic finishing via sol-gel. The nanosol was prepared by co-hydrolysis and condensation of tetraethoxysilane (TEOS) and 1H,1H,2H,2H-fluorooctyltriethoxysilane (FOS), or hexadecyltrimethoxysilane (C16), as precursors in weakly acid medium. The application on cotton was carried out by padding with various impregnation times, followed by drying and thermal treatment, varying the FOS add-on from 5 till 30 % on fabric weight or C16 add-on from 5 to 10 %. Treated samples were tested in terms of contact angles, drop absorption times, washing fastness and characterized by SEM, XPS and FTIR-ATR analyses. In the case of FOS modified nanosol applied with an impregnation time of 24 h or C16 modified nanosol, water contact angles values very close or even higher than 150° were measured, typical of a superhydrophobic surface. The application of the proposed sol-gel process yielded also a satisfactory treatment fastness to domestic washing, in particular for FOS modified nanoso
Enzyme-aided Wool Dyeing: Influence of Internal Lipids
No full textDyeing and diffusion properties of dyes into wool fiber are governed by a membranous structure which is formed
by a matrix protein and lipid components. External lipids (wool wax) are mainly non-polar, while internal lipids consist mainly of sterols, polar lipids (ceramides), and free fatty acids. These components constitute a real hydrophobic barrier to the diffusion of dye molecules and in fact conventional wool dyeing methods are based on long times at temperature near the boil in order to ensure good levels of dye penetration. To limit the action of this barrier and to achieve higher values of dye bath exhaustion operating at temperatures lower than 98 oC, wool fabric was subjected to three different pre-treatments. The first
pre-treatment consisted of the removal of internal lipids by extraction with solvents in order to obtain a higher affinity of the fiber towards the dyes. The second involved hydrolysis with a protease, which leads to the formation of access routes within the fiber to improve the uptake of dyes or other reagents. Finally, the third took into account the combined action of the two previous pre-treatments. The influence of each individual pre-treatment and their combinations on the kinetics and final exhaustion of the dye bath were studied, and assessment of color fastness (to washing and to light) were carried out
Cotton and polyester textiles finishing by sol-gel technique
No full textCurrent efforts of research in the field of textile materials are focused on surface functionalization, by innovative and cost effective processes, to obtain products with new or improved properties and high added value that can widen their industrial application. The interest is focused on flame retardancy, UV-protection, resistance to weathering and microbiological attack, super-hydrophobicity and soil resistance. High finishing durability, high degree of homogeneity and superior chemical-physical properties coupled with a reduction of harmful compounds in textile finishing industry can be reached by the application of an hybrid inorganic-organic coating by sol-gel techniques[1-3]. The aim of this work is to confer a hydrophobic behaviour to cotton and polyester fabrics depositing a modified silica based film by sol-gel technique. Sol gel coatings were prepared mixing tetraetoxysilane-based sols with low amounts of hydrophobic additives (n-propyltrimethoxysilane, hexadecyltrimetoxysilane, 1H,1H,2H,2H–Fluorooctyltriethoxysilane). Moreover a LTP, low temperature plasma, pre-treatment was carried out on fabrics to improve the sol gel coating adhesion and fastness. Treated fabrics were characterized by SEM, FTIR and XPS while their wettability was evaluated by measuring the water contact angle. Best results were obtained with a TEOS/FOS combination (θ=148°) for polyester and TEOS/C16 for cotton (θ=140°). The enhanced coating adhesion, due to plasma surface activation, was confirmed by abrasion and washing fastness tests
Hydrophobic sol-gel finishing for textiles: Improvement by plasma pre-treatment
No full textThe surface of cotton (COT) and polyester (PET) fabrics was modified to create a water-repellent finishing by depositing
a modified silica-based film using the sol-gel technique. TEOS (tetraethoxysilane)-based physically modified sols with 2%
and 11% on weight fabric (o.w.f.) of hydrophobic additives were tested. N-propyltrimethoxysilane (C3), hexadecyltrimethoxysilane
(C16) and 1H,1H,2H,2H-fluorooctyltriethoxysilane (FOS) were investigated as additives.
Furthermore, a low-temperature plasma pre-treatment was used to activate the COTand PET fabric surface to improve
the sol-gel coating adhesion, resistance to abrasion and fastness to washing stresses.
A complete chemical/morphological (Fourier transform infrared, X-ray photoelectron spectroscopy, scanning electron
microscopy) and physical characterization (abrasion and air permeability test) of treated samples was carried out. High
values of y (around 140) on PET and COT samples were obtained with all additives used (C3, C16 and FOS) even at a
low concentration (2%). Due to plasma pre-treatment, interesting water-repellent properties were achieved for PET
(y1⁄4148) treated with TEOS/FOS molar ratio 0.63 and for COT (y1⁄4140) with TEOS/C16 molar ratio 0.63. The
enhanced coating adhesion, due to plasma surface activation, was confirmed by abrasion and washing tests
Applicazione degli enzimi nella tintura della lana
Full text linkIn questo lavoro è stata studiata la possibilità di ridurre la temperatura di tintura convenzionale della lana mediante l’impiego di enzimi proteolitici. Differenti proteasi di origine batterica sono state testate al fine di migliorare l’accessibilità del colorante alla fibra anche a basse temperature. Per ogni tintura sono state determinate le curve di esaurimento del colorante nel bagno di tintura.
I campioni tinti sono stati sottoposti ad una valutazione di danneggiamento mediante osservazione al microscopio elettronico a scansione e a prove dinamometriche per valutare la perdita di carico di rottura ed allungamento. Inoltre, i campioni tinti sono stati sottoposti a prove di solidità ad umido e alla luce, parametro molto importante perché legato alla qualità del materiale ottenuto
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