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UPCommons - E-prints UPC Universitat Politècnica de Catalunya (59.763 recursos)
E-prints UPC cobreix dues finalitats: per una banda, és el dipòsit institucional de la UPC que recull els articles de revista, les comunicacions de congrés i els reports de recerca generats en les activitats de recerca del personal docent i investigador de la universitat; per l'altra, és una eina que permet accelerar la producció científica, allotjant versions de documents prèvies a la publicació en una revista o a les actes d’un congrés.

Articles de revista

Mostrando recursos 1 - 20 de 94

1. Effectiveness of novel xylanases belonging to different GH families on lignin and hexenuronic acids removal from specialty sisal fibres - Valenzuela Mayorga, Susana Valeria; Valls Vidal, Cristina; Roncero Vivero, María Blanca; Vidal Lluciá, Teresa; Díaz Lucea, Pilar; Pastor Blasco, Francisco Ignacio Javier
Background: The effectiveness of xylanases on lignin removal from pulps differs widely depending on the enzyme family, the type of pulp and the bleaching sequence among other factors. Xylanases can also reduce the presence of undesirable hexenuronic acids in the papermaking fibers. The performance of non-commercial xylanases belonging to families GH10, GH30, GH30-CBM35 and GH11, and of the multicomponent xylanase from Paenibacillus barcinonensis for lignin and hexenuronic acids removal from sisal (Agave sisalana) has been evaluated. Results: Sisal pulps were bleached by an XP sequence, where X denotes the enzyme treatment and P a hydrogen peroxide extraction stage. Kappa number,...

2. Enzymatic strategies to improve removal of hexenuronic acids and lignin from cellulosic fibers - Valls Vidal, Cristina; Vidal Lluciá, Teresa; Roncero Vivero, María Blanca
Different enzymatic strategies were applied to improve lignin and hexenuronic acid (HexA) removal. Three laccases (L) with different redox potentials were applied in combination with 1-hydroxybenzotriazole or methyl syringate to softwood sulfite and hardwood kraft fibers. The enzymes with a high-redox potential from Pycnoporus cinnabarinus and Trametes villosa were found to be the most efficient. The bleaching efficiency was not significantly influenced by the presence or absence of HexA in the different types of lignocellulosic fibers.Subsequently, the lignin or HexA removal in the presence of different mediators was evaluated in eucalyptus fibers with the T. villosa laccase (TvL). Natural mediators...

3. Preparation of durable insecticide cotton fabrics through sol–gel treatment with permethrin - Ardanuy Raso, Mònica; Faccini, Mirko; Amantia, David; Aubouy, Laurent; Borja, Guadalupe
This paper presents the development of an industrially viable procedure for the fabrication of durable insecticide textiles based on the sol–gel technique. Permethrin was incorporated on cotton fabrics by a silicon oxide nanocoating applied by conventional padding followed by curing. The effect of the sol–gel process parameters, such as silica solid content and the permethrin/tetraethyl orthosilicate (TEOS) ratio on the insecticide activity and on the textile properties of the resulting fabricswas evaluated. The application of the nanosol coating results in textiles with a high anti-mosquito effect without altering their flexibility and softness.Moreover, this method allows the insecticide content to be...

4. Plasma surface functionalization and dyeing kinetics of Pan-Pmma copolymers - Labay, Cedric; Canal Barnils, Cristina; Rodríguez Sorigué, M. Cristina; Caballero Manresa, Gabriel; Canal Arias, José Ma
Fiber surface modification with air corona plasma has been studied through dyeing kinetics under isothermal conditions at 30 °C on an acrylic-fiber fabric with a cationic dye (CI Basic Blue 3) analyzing the absorption, desorption and fixing on the surface of molecules having defined cationic character. The initial dyeing rate in the first 60 s indicates an increase of 58.3% in the dyeing rate due to the effect of corona plasma on the acrylic fiber surface. At the end of the dyeing process, the plasma-treated fabrics absorb 24.7% more dye, and the K/S value of the acrylic fabric increases by 8.8%....

5. An enzyme-catalysed bleaching treatment to meet dissolving pulp characteristics for cellulose derivatives applications - Quintana, Elisabet; Valls Vidal, Cristina; Vidal Lluciá, Teresa; Roncero Vivero, María Blanca
Bleached cellulose with good end-properties (_90% ISO brightness and 62% cellulose preservation) was obtained by using a totally chlorine-free biobleaching process (TCF). Unbleached sulphite cellulose was treated with Trametes villosa laccase in combination with violuric acid. This enzymatic stage (L) was followed by a chelating stage (Q) and then by a hydrogen peroxide stage reinforced with pressurized oxygen (Po), resulting to an overall LQPo sequence. The use of violuric acid was dictated by the results of a preliminary study, where the bleaching efficiency of various natural (syringaldehyde and p-coumaric acid) and synthetic mediators (violuric acid and 1-hydroxybenzotriazole) were assessed. The...

6. Abrasive elements and abrasion resistance tests for car seat upholstery - Jerkovic, Ivona; Pallarés, Josep Maria; Ardanuy Raso, Mònica; Capdevila Juan, Francisco Javier
The weight of textile components in automobiles is expected to rise to 35 kg by 2020, and the average lifetime of a vehicle is about 12 years. Car seats are the most important part of the interior decoration, and polyester is the most widely used material in car seat covering. Abrasion resistance tests are used to quantify the duration of car seat upholstery in normal usage, and this is one of the most important requirements. Several testing methods, standards, and car producer specifications have been developed to define the abrasion resistance of specified materials, and pre-tests have been taken to...

7. Relationship between microstructure and properties of false-twist textured and stabilized polylactide. Part 2: physicochemical characterization, accessibility of the amorphous phase and dyeing behavior - Cayuela Marín, Diana; Montero, Lucila; Riva Juan, Ascensión; Prieto Fuentes, María Remedios; Martí, Meritxell; Manich, Albert M.
Polylactide fibers (PLA), textured by false twist at different temperatures (135, 150 and 165º C) and draw ratios (1.30, 1.35 and 1.40) were stabilized by the application of a continuous thermal treatment at 100º C and 50 m/min. The effect of thermal stabilization on the microstructure was determined by physicochemical tests such as iodine sorption or differential solubility. Iodine sorption and differential solubility are closely related to the crystallinity of the samples. Stabilization enhances crystallinity and orientation with the result that differences between the samples are diminished. Color value differences, albeit reduced, in some cases exceed the accepted limits. Color...

8. Laccase-mediated coupling of nonpolar chains for the hydrophobization of lignocellulose - García Ubasart, Jordi; Vidal Lluciá, Teresa; Torres López, Antonio Luis; Rojas, Orlando J.
We investigate the use of laccase enzymes to couple short nonpolar chains containing aromatic groups onto flax fibers and nanofibrillated cellulose (NFC) with different lignin contents. Trametes villosa, Pycnoporus cinnabarinus, and Myceliophthora thermophila were used to facilitate surface coupling and to produce materials with different levels of hydrophobicity. Heat treatment of fiber webs after lacccase-mediated coupling markedly increased the resistance to water absorption. The highest hydrophobization levels of flax fibers was achieved by coupling dodecyl 3,4,5-trihydroxybenzoate (HB-C12), which yielded water contact angles (WCAs) of 80−96 degrees and water absorption times (drop tests) of ca. 73 min. The results from apparent...

9. Biomodification of cellulose flax fibers by a new cellulase - Garcia Ubasart, Jordi; Torres López, Antonio Luis; Vila, Carlos; Pastor, Francisco J.; Vidal Lluciá, Teresa
The potential of the new cellulase Cel9B from Paenibacillus barcinonensis for the modification of cellulose flax fibers was for the first time assessed in this work. Cel9B treatments were found to enhance the development of properties during the refining of fibers, the precise effects depending on the enzyme dose used. Scanning electron micrographs showed the treatments to alter flax fiber surface and cause defibrillation, peeling and fiber wall removal. Zero-span tensile strength was determined to elucidate the changes in intrinsic resistance of cellulose fibers and solubilization of carbohydrates evaluated by HPLC. Low Cel9B doses resulted in improved tensile strength in...

10. Effect of commercial xylanases applied at extreme conditions in a eucalyptus pulp mill - Fillat, Úrsula; Roncero Vivero, María Blanca; Bassa, Alexandre; Sacón, Vera Maria
In this study, we examined the effect of treating eucalyptus pulp with various commercial xylanases to identify the most effective enzyme for use under the industrial bleaching conditions used at the Jacareí mill of the Brazilian firm Fibria, which include a high pH and temperature. Based on the results, the use of two of the nine enzymes studied reduced the kappa number by 1.5 units, increased brightness by 2.5% ISO, and decreased hexenuronic acids (HexA) content by more than 10 μmol/g relative to a control treatment in the absence of enzyme. The most marked changes in brightness were observed on...

11. Laccase for biobleaching of eucalypt kraft pulp by means of a modified industrial bleaching sequence - Moldes, Diego; Vidal Lluciá, Teresa
Biobleaching of kraft pulp is a possible application of laccase, but it has not been described in detail for complete industrial bleaching sequences yet. Therefore, in this work, the biobleaching of Eucalyptus globulus kraft pulp was performed using a modified industrial totally chlorine-free sequence. The modification consisted in the substitution of an enzymatic delignification stage, based on the application of laccase from Trametes villosa, for the first alkaline extraction one. The enzymatic stage was performed with several synthetic and natural mediators, namely 1-hydroxybenzotriazole (HBT), violuric acid (VA), methyl syringate, and syringaldehyde. Several pulp properties were analyzed after each stage of...

12. Effect of residual lignin and heteropolysaccharides in nanofibrillar cellulose and nanopaper from wood fibers - Ferrer Carrera, Ana; Quintana, Elisabet; Filpponen, Ilari; Solala, Iina; Vidal Lluciá, Teresa; Rodríguez Pascual, Alejandro; Laine, Janne; Rojas, Orlando J.
Unbleached (UN), oxygen-delignified and fully-bleached (FB) birch fibers with a residual lignin content of ca. 3, 2 and\1 %, respectively, were used to produce nanofibrillated cellulose (NFC) and nanopaper by using an overpressure device. The tensile index, elongation and elastic modulus of nanopaper were compared and the effect of residual cellwall components accessed. Under similar manufacturing conditions, UN NFC produced nanopaper with a density of 0.99 g/cm3, higher than that from FB NFC (0.7 g/cm3). This translated in much lower air permeability in the case of UN nanopaper (1 and 11 mL/min for UN and FB samples, respectively). Fundamentally, these...

13. Continuous reuse of water and electrolyte from decolorized reactive dyebaths - López Grimau, Víctor; Gutiérrez Bouzán, María Carmen; Valldeperas Morell, José; Crespi Rosell, Martin
In this work, the feasibility of reusing water and salt from reactive dyebaths after electrochemical decolourization was evaluated. Dyeing series of ten reuses with three reactive dyes (Navy Blue Procion H-EXL, Crimson Procion H-EXL and Yellow Procion H-EXL) were carried out (individually and in a trichromie) and color differences and total organic carbon values were measured to study how the successive reuses affect the quality dyeing. The first reuse produced dyeings with low colour differences with respect to a standard dyeing. In the subsequent reuses, colour differences increased until they reached a constant value at the 4th or 5th reuse, following a similar behavior to the organic...

14. Washing wool with surfactants and a non-toxic solvent microemulsion: influence of water hardness - Carrión Fité, Francisco Javier
In this work, detersive power (soil removal) was studied after washing a soiled wool fabric with addition of a non-toxic solvent microemulsion to conventional washing detergent formulations with the aim of improving the performance of the conventional washing. The non-toxic solvent used was dimethyl sulfoxide micro-dispersed with an amphoteric surfactant as emulsifier. The fabric was washed with biodegradable non-ionic surfactants such as an alcohol ethoxylate (AE) with 7 mE.O. and an alkyl polyglucoside with 1.4 glucoside groups (APG). The fabric used was EMPA 107 wool (soiled with standard impurities). The non-ionic surfactants were used separately and in mixture in varying...

15. Cyclodextrin functionalization of several cellulosic substrates for prolonged release of antibacterial agents - Cusola Aumedes, Oriol; Tabary, Nicolas; Naceur Belgacem, Mohamed; Bras, Julien
Several cellulosic substrates have been surface-functionalized with cyclomaltoheptaose (b-cyclodextrin, b-CD) using citric acid as a crosslinker agent to obtain new surface-modified materials able to release antiseptic molecules over a prolonged period, in view of their use in medical domain. Three different commercial cellulosic substrates were used, namely: (i) an uncoated paper, (ii) a crepe paper, and (iii) a medical bandage. They were successfully grafted by a crosslinked polymer consisting on b-CD molecules as assessed by scanning electron microscopy and Fourier transform infrared spectroscopy analysis. Several time–temperature kinetic cycles were performed to reach the optimum curing parameters. The grafted and nongrafted...

16. The PVP/VI copolymer dye transfer inhibition agent during the washing of the polyester fabric - Carrión Fité, Francisco Javier
The objective of this research was to study the effect of the copolymer polyvinylpyrrolidone/vinylimidazole (PVP/VI) for use as a dye transfer inhibitor (DTI) during the washing of dyed polyester fabric, depending on the detergent components. The DTI was used to find its efficiency during repeated washings of polyester fabric dyed with disperse dyes. At the same time, its efficiency was tested fer preventing dye migration to other fabrics, such as polyester, cellulose diacetate, acrylic, polyamide, cotton and wool. The influence of anionic (SDBS) and non-ionic (alkyl ethoxylates with 6 EO-groups) surfactants in different proportions and with zeolite as a builder...

17. Application of surface enzyme treatments using laccase and a hydrophobic compound to paper-based media - Cusola Aumedes, Oriol; Valls Vidal, Cristina; Vidal Lluciá, Teresa; Roncero Vivero, María Blanca
A new approach for the hydrophobization of finished cellulosic substrates based on a previously reported enzymatic technique is proposed. Commercial finished paper was hydrophobized by using laccase from Trametes villosa in combination with lauryl gallate (LG) as hydrophobic compound. The efficiency of the method was increased by the use of a lignosulfonate as a natural dispersant to improve the surface distribution of LG on the paper, raise its hydrophobicity and help preserve the enzyme activity. No similar threefold effect from a single compound for the improvement of enzymatic treatments was previously reported. The influence of processing conditions including the LG...

18. Laccase from Pycnoporus cinnabarinus and phenolic compounds: can the efficiency of an enzyme mediator for delignifying kenaf pulp be predicted? - Andreu Terrén, Glòria; Vidal Lluciá, Teresa
In this work, kenaf pulp was delignified by using laccase in combination with various redox mediators and the efficiency of the different laccase–mediator systems assessed in terms of the changes in pulp properties after bleaching. The oxidative ability of the individual mediators used (acetosyringone, syringaldehyde, p-coumaric acid, vanillin and actovanillone) and the laccase–mediator systems was determined by monitoring the oxidation–reduction potential (ORP) during process. The results confirmed the production of phenoxy radicals of variable reactivity and stressed the significant role of lignin structure in the enzymatic process. Although changes in ORP were correlated with the oxidative ability of the mediators,...

19. Enzymatic grafting of natural phenols to flax fibres: development of antimicrobial properties - Fillat Latorre, Amanda; Gallardo Román, Óscar; Vidal Lluciá, Teresa; Pastor Blasco, Francisco I. Javier; Díaz Lucea, Pilar; Roncero Vivero, María Blanca
Unbleached flax fibres for paper production were treated with laccase from Pycnoporus cinnabarinus and low molecular weight phenols (syringaldehyde – SA, acetosyringone – AS and p-coumaric acid – PCA) to evaluate the potential of this treatment to biomodify high cellulose content fibres. After the enzymatic treatment with the phenols, an increase in kappa number was found, probably due to a covalent binding of the phenoxy radicals on fibres. Grafting was more evident in pulps treated with PCA (an increase of 4 kappa number points with respect to the laccase control was achieved). Paper handsheets from treated pulps showed antimicrobial activity...

20. Use of cyclic voltammetry as an effective tool for selecting effcient enhancers for oxidative bioprocesses: importance of pH - Aracri, Elisabetta; Tzanov, Tzanko; Vidal Lluciá, Teresa
Seven natural phenols and two synthetic compounds were evaluated by means of cyclic voltammetry as enhancers for the oxidation of the lignin model compound veratryl alcohol (VAl) and a sulfonated lignin (SL). Their electrochemical behaviors and catalytic efficiencies (CEs) against both substrates were assessed as a function of pH. A general increase in CE of the phenols was for the first time observed in the oxidation of VAl at pH 7 and 8. Methyl syringate (MS), syringic acid (SRC), and syringaldehyde (SRD) exhibited the highest CEs against VAl among the studied phenolic compounds despite the reduced stabilities of their phenoxy...

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