Bacterial cellulose for increasing barrier properties of paper products

Bacterial cellulose was combined with wood cellulose papers in order to obtain biomaterials with increased barrier properties. For this purpose, different parameters were assessed: two producing bacterial strains (Komagataeibacter xylinus and Gluconacetobacter sucrofermentans), two paper supports to hold bacterial cellulose (filter paper and eucalyptus paper), two kinds of combined biomaterials (composite and bilayer) and two drying temperatures (90ºC and room temperature). Papers with increased barrier properties (100º of water contact angle, 1220s of water drop test and air permeability ˂1µm (Pa·s)-1) were obtained by the addition of bacterial cellulose to each paper support. However, due to the lower initial barrier properties of filter paper, higher improvements were produced with this paper. In addition, bacterial cellulose provided smoother surfaces with higher gloss without a detrimental effect on physical properties. Higher resistance to water absorption was obtained with K. xylinus possibly explained by its longer size fibers than G. sucrofermentans, as analysed by SEM. Smoothness and gloss were specially increased in the bilayer biomaterial although resistance to air and water were further improved in the composite. In this biomaterial drying at high temperature had a detrimental effect. SEM analysis of the products obtained showed the intimate contact among fibers of bacterial cellulose and wood paper. Results obtained show the contribution of bacterial cellulose to improve the properties of paper and its potential for the design of new added value paper products from biomass

Bacterial cellulose for increasing barrier properties of paper products

Bacterial cellulose was combined with wood cellulose papers in order to obtain biomaterials with increased barrier properties. For this purpose, different parameters were assessed: two producing bacterial strains (Komagataeibacter xylinus and Gluconacetobacter sucrofermentans), two paper supports to hold bacterial cellulose (filter paper and eucalyptus paper), two kinds of combined biomaterials (composite and bilayer) and two drying temperatures (90 °C and room temperature). Papers with increased barrier properties (100° of water contact angle, 1220 s of water drop test and air permeability < 1 µm (Pa s)-1) were obtained by the addition of bacterial cellulose to each paper support. However, due to the lower initial barrier properties of filter paper, higher improvements were produced with this paper. In addition, bacterial cellulose provided smoother surfaces with higher gloss without a detrimental effect on physical properties. Higher resistance to water absorption was obtained with K. xylinus possibly explained by its longer size fibers than G. sucrofermentans, as analysed by SEM. Smoothness and gloss were specially increased in the bilayer biomaterial although resistance to air and water were further improved in the composite. In this biomaterial drying at high temperature had a detrimental effect. SEM analysis of the products obtained showed the intimate contact among fibers of bacterial cellulose and wood paper. Results obtained show the contribution of bacterial cellulose to improve the properties of paper and its potential for the design of new added value paper products from biomassPostprint (author's final draft

Biorefinery: the paper mill of tomorrow

Peer Reviewe

Flax fibre modification using enzyme systems to obtain high-value cellulose products

The aim of this thesis is to modify flax pulp fibres (Linum usitatissimum) by more friendly environmental processes. Pulp and paper research is focussing through enzyme systems investigation for developing green chemistry technologies due to existing environmental concerns and to legal restrictions. Moreover, it exists also an increasing strategic interest in using flax fibres to obtain high-quality specialty papers. That is why we study the application of biotechnology as an efficient alternative to traditional industrial processes based on the use of chemical agents. This work is framed by two of the main research topics of the Paper and Graphic Specialty Laboratory in the Textile and Paper Engineering Department of the Universitat Politècnica de Catalunya. One research line is based on pulp bleaching and is focused basically on the study of enzymatic systems as biobleaching agents; the other research topic that has been recently introduced in our investigation group is the use of enzymes as functionalisation agents by promoting the grafting of several compounds. Laccase is the main enzyme used in this thesis; it is an oxidoreductase that can assist reactions in an eco-friendly way since laccase uses air and produces water as the only by-product. Moreover, laccase can work under mill conditions and has wide application potential. The first part of this thesis involved the use of enzymes to bleach flax pulp. The aim was to explore the potential of various natural mediators (lignin-derived compounds) for delignifying flax fibres in order to identify the most efficient and ecofriendly choice among them. Afterwards, we assessed the use of various enzyme delignification stages in an industrial bleaching sequence. The ensuing totally chlorine free (TCF) sequence comprised various laccase-mediator system treatments (L stage) followed by a by a chelating stage (Q stage) and a subsequent bleaching step with hydrogen peroxide (Po stage). A xylanase pretreatment was additionally carried out. Laccases used came from the fungi Pycnoporus cinnabarinus and Myceliophthora thermophila; the performance of several natural mediators was compared with the obtained with the application of various synthetic mediators. In addition, the lack of studies on the properties of effluents from the treatment of non-wood pulp with laccase and natural mediators led A-1 A-2 us to examine effluent properties upon biotreatments and after different bleaching stages. The results obtained warrant upscaling any of the biobleaching sequences for flax pulp as they provide sustainable flax fibre with a high cellulose content and brightness above 80% ISO. The use of xylanase pretreatment was found to efficiently remove HexA and enhance delignification by laccase

Elucidating the effects of laccase-modifying compounds treatments on bast and core fibers in flax pulp

Laccases in combination with various chemical compounds have been tested with a view to obtain environmental friendly, high-value paper products from unbleached flax pulp, which is currently being assessed as a raw material for biotechnological innovation. With the aim of better understanding the effects of violuric acid (VA) and p-coumaric acid (PCA) on flax pulp, changes in the chemical composition of the two major fiber types it contains were assessed. Following classification, the initial pulp was split into two fractions according to fiber size, namely: bast (long) fibers and core (short) fibers. Fiber size was found to significantly influence the properties of pulp and it response to various laccase treatments. The laccase-PCA treatment substantially increased kappa number (KN) and color in both fiber fractions, which suggests grafting of the phenolic compound onto fibers. On the other hand, the laccase-VA treatment produced long fibers with a low lignin content (KN¼1.3) and a high brightness (5% points higher than for the control fraction), which testifies to its bleaching efficiency. Both biotreatments produced long fibers containing highly crystalline cellulose and caused HexA removal from global and short fibers. On the other hand, the laccase treatments caused no morphological changes in the fibers, the integrity of which was largely preserved. As shown here, laccase acts as polymerization agent with PCA and as delignification agent with VA; also, the two enzymes systems act differently on bast and core fibers

Panel products directory

SIGLEAvailable from British Library Document Supply Centre- DSC:Vq94/05920 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Study of the effects on bast and core flax fibres of laccase + mediator/phenol treatments

Postprint (published version

Perspectives on European standards for wood-based panels

SIGLEAvailable from British Library Document Supply Centre- DSC:2277.485(BRE-IP--9/93) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Elucidating the effects of laccase-modifying compounds treatments on bast and core fibers in flax pulp

Laccases in combination with various chemical compounds have been tested with a view to obtain environmental friendly, high-value paper products from unbleached flax pulp, which is currently being assessed as a raw material for biotechnological innovation. With the aim of better understanding the effects of violuric acid (VA) and p-coumaric acid (PCA) on flax pulp, changes in the chemical composition of the two major fiber types it contains were assessed. Following classification, the initial pulp was split into two fractions according to fiber size, namely: bast (long) fibers and core (short) fibers. Fiber size was found to significantly influence the properties of pulp and it response to various laccase treatments. The laccase-PCA treatment substantially increased kappa number (KN) and color in both fiber fractions, which suggests grafting of the phenolic compound onto fibers. On the other hand, the laccase-VA treatment produced long fibers with a low lignin content (KN¼1.3) and a high brightness (5% points higher than for the control fraction), which testifies to its bleaching efficiency. Both biotreatments produced long fibers containing highly crystalline cellulose and caused HexA removal from global and short fibers. On the other hand, the laccase treatments caused no morphological changes in the fibers, the integrity of which was largely preserved. As shown here, laccase acts as polymerization agent with PCA and as delignification agent with VA; also, the two enzymes systems act differently on bast and core fibers