Cellulose Fibre-Reinforced Biofoam for Structural Applications

Traditionally, polymers and macromolecular components used in the foam industry are mostly derived from petroleum. The current transition to a bio-economy creates demand for the use of more renewable feedstocks. Soybean oil is a vegetable oil, composed mainly of triglycerides, that is suitable material for foam production. In this study, acrylated epoxidized soybean oil and variable amounts of cellulose fibres were used in the production of bio-based foam. The developed macroporous bio-based architectures were characterised by several techniques, including porosity measurements, nanoindentation testing, scanning electron microscopy, and thermogravimetric analysis. It was found that the introduction of cellulose fibres during the foaming process was necessary to create the three-dimensional polymer foams. Using cellulose fibres has potential as a foam stabiliser because it obstructs the drainage of liquid from the film region in these gas-oil interfaces while simultaneously acting as a reinforcing agent in the polymer foam. The resulting foams possessed a porosity of approximately 56%, and the incorporation of cellulose fibres did not affect thermal behaviour. Scanning electron micrographs showed randomly oriented pores with irregular shapes and non-uniform pore size throughout the samples

Topochemical engineering of composite hybrid fibers using layered double hydroxides and abietic acid

Topochemical engineering of hybrid materials is an efficient way of synthesizing hydrophobic and highly tensile fiber composites by utilizing the intermolecular hydrogen bonds in natural materials. These materials include wood pulp fibers, abietic acid (resin acid) and inexpensive metal salts. In this work, a hybrid composite was created using bleached and unbleached kraft pulp fibers as cellulose platform. In situ co-precipitation of layered double hydroxide (LDH) was performed to grow LDH crystals on the surface of the cellulose fibers, followed by the immobilization of abietic acid (AA) on LDH-grafted cellulose. Here we aimed to benefit from the hydrogen bonding between -OH groups of cellulose and LDH, and the -COOH groups of AA to obtain charge-directed assembly of one material on the other material. Thus, composite hybrid fibers (C-HF) were produced and then characterized by optical (CAM), spectroscopic (XRD, IR) and microscopic techniques (SEM) to determine their average length and distribution, structure and purity, bonding, and morphology. These fibers further were tested for water contact angle (hydrophobicity), oil absorption (lipophilicity), tensile strength and ISO brightness measurements. The performance of C-HF was compared with unmodified reference fibers (REF), fibers composed with only AA (C-F) and LDH-hybridized fibers (HF). The results revealed a variety of correlations between materials and their properties due to characteristic surface morphology, functional groups, hydrogen bonding and natural co-materials such as lignin and hemicelluloses. Attractive and repulsive van der Waals forces between material entities play a crucial role in the resulting properties

Hydrogen peroxide bleaching of cellulose pulps obtained from brewer’s spent grain

Brewer’s spent grain (BSG) was evaluated for bleached pulp production. Two cellulose pulps with different chemical compositionswere produced by soda pulping: one from the original raw material and the other from material pretreated by dilute acid. Both of them were bleached by a totally chlorine-free sequence performed in three stages, using 5% hydrogen peroxide in the two initial, and a 0.25 NNaOHsolution in the last one. Chemical composition, kappa number, viscosity, brightness and yield of bleached and unbleached pulps were evaluated. The high hemicellulose (28.4% w/w) and extractives (5.8% w/w) contents in original BSG affected the pulping and bleaching processes.However, soda pulping of acid pretreated BSG gave a celluloserich pulp (90.4% w/w) with low hemicellulose and extractives contents (7.9% w/w and <3.4% w/w, respectively), which was easily bleached achieving a kappa number of 11.21, viscosity of 3.12 cp, brightness of 71.3%, cellulose content of 95.7% w/w, and residual lignin of 3.4% w/w. Alkaline and oxidative delignification of acid pretreated BSG was found as an attractive approach for producing high-purity, chlorine-free cellulose pulp.FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo), Brazil.CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico).Capes (Coordenação de Aperfeiçoamento de Pessoal de Nível Superior)

Paper And Surface Chemistry Part Ii - Coating And Printability [papel E Química De Superfície Parte Ii - Revestimento E Printabilidade]

Surface chemical interactions are important in many steps of paper manufacturing and converting. Interactions between fibres and colloidal particles, polymers, minerals and dyes are fundamental in papermaking, for example in floc formation, sizing and coating adhesion as well as in paper printability. Most papermaking interactions are complex and not very well understood, consequently, many paper formulations are designed according to an empirical trial-and-error approach. This work is a critical literature review of some interactions present in papermaking, coating and printing. In the first part of the review the interactions concerning the pulp fibres and other papermaking components in the wet-end were. In this second part the surface chemistry interactions present in coating formulation and printing are discussed. The surface engineering of paper and coating is also presented as a good potential for improving coating formulation, adhesion and paper printability. The knowledge of surface chemical interactions can be useful, not only for patents and product development, but also for improving in troubleshooting and customers support.6357583Alince, B., Lepoutre, P., Porosity and optical properties of clay coatings (1980) J. Coll. Interf. Sci., 76 (2), p. 439Allem, R., Characterization of paper coatings by scanning electron microscopy and image analysis (1998) J. Pulp Pap. Sci., 24 (10), p. 329Aspler, J.S., Interactions of ink and water with the paper surface in printing (1993) Nord. Pulp Pap. Res. J., 8 (1), p. 68Barber, E.J., Effect of hydrocolloids on coating color operability and coated paper properties (1973) Tappi J., 56 (1), p. 52Beghello, L., Some factors that influence fiber flocculation (1998) Nord. Pulp Pap. Res. J., 13 (4), p. 274Berg, J.C., The importance of acid base interactions in wetting, coating, adhesion and related phenomena (1993) Nord. Pulp Pap. Res. J., 8 (1), p. 75Chen, C.Y., Pruett, R.J., Wygant, R.W., A review of techniques for characterizing paper coating surfaces, structures and printability (1995) Proc. Tappi Coating Adv. Fund. Symp., p. 1Dahlvik, P., (2000) Thermal thickening of paper coatings, , Tese de Doutorado, Universidade Åbo Akademi, ÅboDahlvik, P., Ström, G., Eklund, D., Variations in calcium ion concentration and pH influencing coating colour rheology, dewatering and immobilization (1997) Nord. Pulp Pap. Res. J., 12 (1), p. 61Diz, H.M.M., Rand, B., The variable nature of the isoelectric point of the edge surface of kaolinite (1989) Br. Ceram. Trans. J., 88, p. 162Dollimore, D., Horridge, T.A., Dependence of flocculation behavior of china clay - Polyacrylamide suspensions on the suspensions pH (1973) J. Coll. Interf. Sci., 42 (3), p. 581Donigian, D.W., Ishley, J.N., Wise, K., Coating pore structure and offset printed gloss (1997) Tappi J., 80 (5), p. 163Elftonson, J., Ström, G., Penetration of aqueous solution into models for coating layers (1995) Proc. Tappi Coating Adv. Fund. Symp., p. 17Engström, G., Morin, V., Quantitative description of the increase in surface roughness of the base paper during coating (1994) Nord. Pulp Pap. Res. J., 9 (2), p. 106Erbil, H.Y., Calculation of spreading pressure of water on cellulosic films from contact angle data (1997) Turkey J. Chem., 21, p. 332Eriksson, U., Rigdahl, M., Dewatering of coating colors containing CMC or starch (1994) J. Pulp Pap Sci., 20 (11), p. 333Evans, D.F., Wennerström, H., (1999) The colloidal domain, where physics, chemistry, biology and technology meet, p. 426. , Willey, New YorkFadat, G., Rigdahl, M., Interactions in coating colors Part 2. Effects of ionic strength (1986) Nord. Pulp Pap. Res. J., 1 (4), p. 37Fardim, P., (1999) Composição química da superfície da polpa kraft de eucalyptus: Caracterização e influências nas propriedades físicas e físico-químicas das fibras, , Tese de Doutorado. Instituto de Química, Universidade Estadual de Campinas, UNICAMPGane, P.A.C., Waters, P., McGenity, P., Factors influencing the runnability of coating colors at high speed (1992) Proc. Tappi Coating Conf., p. 117Granier, V.V., Sartre, A., Joanicot, M.M., Adhesion of latex particles on inorganic surfaces (1994) Tappi J., 77 (5), p. 419Grön, J., Eklund, D., Temperature effect on rheological and dewatering properties for starch-based coating colors (1998) Nord. Pulp Pap. Res. J., 13 (1), p. 10Grön, J., Kuni, S., The impact of different coating pigments and molecular weight of carboxymethyl cellulose on coating structure (1995) Proc. Tappi Coating Conf., p. 447Grön, J., Dahlvik, P., Ström, G., Influence of starch modification on the chemical composition and structure of coated layers (1998) Nord. Pulp Pap, Res. J., 13 (2), p. 119Grön, J., (1998) Coating suspension structure and rheology, , Tese de Doutorado, Universidade Åbo Akademi, ÅboIsraelachvili, J., 1996Joanicot, M., Wong, K., Cabane, B., Structure of latex films (1993) Proc. Tappi Coating Conf., p. 383Kline, J.E., Fundamental aspects of latex mobility in paper coatings (1993) Proc. Tappi Adv. Coating Fund. Symp., p. 93Krieger, I.M., Dougherty, T.J., A mechanism for non-Newtonian flow in suspensions of rigid spheres (1957) Trans. Soc. Rheol., 3, p. 137Lepoutre, P., Lord, D., Desestabilized clay suspensions: Flow curves and dry film properties (1990) J. Coll. Interf. Sci., 134 (1), p. 66Malik, J.S., Kline, J.E., A study of the effect of water soluble polymers on water holding and binder migration tendencies of coatings (1992) Proc. Tappi Coating Conf., p. 105McGenity, P.M., Gane, P.A.C., Husband, J.C., Engley, M.S., Effect of interactions between coating color components on rheology, water retention and runnability (1992) Proc. Tappi Coating Conf., p. 133Perry, S.S., Somorjai, G.A., Characterization of organic surfaces (1994) Anal. Chem., 63 (7), p. 403Rand, B., Melton, I.E., Particle interactions in aqueous kaolinite suspensions 1. Effect of pH and electrolyte upon the mode of particle interaction in homoionic sodium kaolinite suspensions (1977) J. Coll. Interf. Sci., 60 (2), p. 308Reinbold, I., Ulrich, H., Possibilities and limitations of high solids coating colors (1979) Proc. Tappi Coaling Conf., p. 31Sanders, N.D., The effect of surface modification of pigments on colloidal stability and structural performance (1992) J. Pulp Pap. Sci., 18 (5), p. 169Sandås, S., Salminen, P., Pigment-co binder interactions and their impact on coating rheology, dewatering and performance (1991) Tappi J., 74 (12), p. 179Schramm, G., (1994) A practical approach to rheology and rheometry, , Haake GmbH Publication, KarlsruheScott, W.E., Abbott, J.C., Trosset, S., (1995) Properties of paper: An introduction, p. 161. , Tappi Press, AtlantaShaw, D.J., (1980) Introduction to colloid and surface chemistry, p. 208. , Butterworth, LondresStenius, P., Järnström, L., Rigdahl, M., Aggregation in concentrated kaolin suspensions stabilized by poiyacrylate (1990) Coll. Surf., 51, p. 219Ström, G., Härdin, A.-M., Salminen, P., A novel approach for improving fibre coverage during blade coating (1995) Nord. Pulp Pap. Res. J., 10 (4), p. 227Swerin, A., (1995) Flocculation and fiber network strength in papermaking suspensions flocculated by retention aids systems, , Tese de Doutorado. Royal Institute of Technology, EstolcomoVan Gilder, R.L., Purfeerst, R.D., The effect of coating color solids on properties and surface uniformity (1986) Tappi J., 69 (5), p. 119Verhoeff, J., Hart, J.A., Gallay, W., Sizing and the mechanism of penetration of water into paper (1963) Pulp Pap. Mag. Can., 64, pp. T509Wang, X.Q., Grön, J., Eklund, D., Temperature dependence for adsorption of carboxymethyl cellulose on clay (1996) Proc. Tappi Coating Conf., p. 79Whalen-Shaw, M., Gautam, N., A model for colloidal and rheological characteristics of kaolin latex NaCMC formulations (1990) Proc. Tappi Coating Conf., p. 371Whalen-Shaw, M., Coating structure - Part I: A mechanistic view to the development of wet coating structure (1989) Proc. Tappi Coating Conf., p. 9Wickman, M., (1998) Surface chemical behavior of alkyd resins in offset printing inks, , Tese de Doutorado. Royal Instute of Technology, EstolcomoYoung, T.S., Fu, E., Associative behavior of cellulosic thickeners and its implications on coating structure and rheology (1991) Tappi J., 74 (4), p. 197Zang, Y.-H., Aspler, J.S., The effect of surface binder content on print density and ink receptivity of coated paper (1998) J. Pulp Pap. Sci., 24 (5), p. 14

Paper And Surface Chemistry - Part 2 - Coating And Printability

The surface chemical interaction that was involved in manufacturing and printing of paper was investigated. Different treatments like- calendering or coating were applied to paper surfaces to improve printability, optical properties and strength. Coating was found as the mixture of minerals, colloidal particles and dissolved polymers applied on the base paper that require optimum flow properties. It was found that the concept of surface engineering applied in coating and printing ink formulations made possible the development of economically beneficial paper.194456Alince, B., Lepoutre, P., Porosity and optical properties of clay coatings (1980) J. Coll. Interf. Sci., 76 (2), p. 439Allem, R., Characterization of paper coatings by scanning electron microscopy and image analysis (1998) J. Pulp Pap. Sci., 24 (10), p. 329Aspler, J.S., Interactions of ink and water with the paper surface in printing (1993) Nord. Pulp Pap. Res. J., 8 (1), p. 68Barber, E.J., Effect of hydrocolloids on coating color operability and coated paper properties (1973) Tappi J., 56 (1), p. 52Beghello, L., Some factors that influence fiber flocculation (1998) Nord. Pulp Pap. Res. J., 13 (4), p. 274Berg, J.C., The importance of acid base interactions in wetting, coating, adhesion and related phenomena (1993) Nord. Pulp Pap. Res. J., 8 (1), p. 75Chen, C.Y., Pruett, R.J., Wygant, R.W., A review of techniques for characterizing paper coating surfaces, structures and printability (1995) Proc. Tappi Coating Adv. Fund. Symp., p. 1Dahlvik, P., (2000) Thermal Thickening of Paper Coatings, , Doctoral Thesis, Åbo Akademi University, Turku/ÅboDahlvik, P., Ström, G., Eklund, D., Variations in calcium ion concentration and pH influencing coating colour rheology, dewatering and immobilization Nord (1997) Pulp Pap. Res. J., 12 (1), p. 61Diz, H.M.M., Rand, B., The variable nature of the isoelectric point of the edge surface of kaolinite (1989) Br. Ceram. Trans. J., 88, p. 162Dollimore, D., Horridge, T.A., Dependence of flocculation behavior of china clay - Polyacrylamide suspensions on the suspensions pH (1973) J. Coll. Interf. Sci., 42 (3), p. 581Donigian, D.W., Ishley, J.N., Wise, K., Coating pore structure and offset printed gloss (1997) Tappi J., 80 (5), p. 163Elftonson, J., Ström, G., Penetration of aqueous solution into models for coating layers (1995) Proc. Tappi Coating Adv. Fund. Symp., p. 77Engström, G., Morin, V., Quantitative description od the increase in surface roughness of the base paper during coating (1994) Nord. Pulp Pap. Res. J., 9 (2), p. 106Erbil, H.Y., Calculation of spreading pressure of water on cellulosic films from contact angle data (1997) Turkey J. Chem., 21, p. 332Eriksson, U., Rigdahl, M., Dewatering of coating colors containing CMC or starch (1994) J. Pulp Pap Sci., 20 (11), p. 333Evans, D.F., Wennerström, H., (1999) The Colloidal Domain, Where Physics, Chemistry, Biology and Technology Meet, p. 426. , Willey, New YorkFadat, G., Rigdahl, M., Interactions in coating colors Part 2. Effects of ionic strength (1986) Nord. Pulp Pap. Res. J., 1 (4), p. 37Fardim, P., (1999) Surface Chemical Composition of Eucalyptus Kraft Pulp: Caharacterisation and Influences on Strength and Physicochemical Properties of Fibres, , PhD Thesis, Instituto de Química, Universidade Estadual de Campinas, UNICAMP, CampinasGane, P.A.C., Waters, P., McGenity, P., Factors influencing the runnability pf coating colors at high speed (1992) Proc. Tappi Coating Conf., p. 117Granier, V.V., Sartre, A., Joanicot, M.M., Adhesion of latex particles on inorganic surfaces (1994) Tappi J., 77 (5), p. 419Grön, J., Eklund, D., Temperature effect on rheological and dewatering properties for starch-based coating colors (1998) Nord. Pulp Pap. Res. J., 13 (1), p. 10Grön, J., Kuni, S., The impact of different coating pigments and molecular weight of carboxymethyl cellulose on coating structure (1995) Proc. Tappi Coating Conf., p. 447Grön, J., Dahlvik, P., Ström, G., Influence of starch modification on the chemical composition and structure of coated layers (1998) Nord. Pulp Pap. Res. J., 13 (2), p. 119Grön, J., (1998) Coating Suspension Structure and Rheology, , Doctoral Thesis, Åbo Akademi University, Turku/ÅboJoanicot, M., Wong, K., Cabane, B., Structure of latex films (1993) Proc. Tappi Coating Conf., p. 383Kline, J.E., Fundamental aspects of latex mobility in paper coatings (1993) Proc. Tappi Adv. Coating Fund. Symp., p. 93Krieger, I.M., Dougherty, T.J., A mechanism for non-Newtonian flow in suspensions of rigid spheres (1957) Trans. Soc. Rheol., 3, p. 137Lepoutre, P., Lord, D., Desestabilized clay suspensions: Flow curves and dry film properties (1990) J. Coll. Interf. Sci., 134 (1), p. 66Malik, J.S., Kline, J.E., A study of the effect of water soluble polymers on water holding and binder migration tendencies of coatings (1992) Proc. Tappi Coating Conf., p. 105McGenity, P.M., Gane, P.A.C., Husband, J.C., Engley, M.S., Effect of interactions between coating color components on rheology, water retention and runnability (1992) Proc. Tappi Coating Conf., p. 133Perry, S.S., Somorjai, G.A., Characterization of organic surfaces (1994) Anal. Chem., 63 (7), p. 403Rand, B., Melton, I.E., Particle interactions in aqueous kaolinite suspensions 1. Effect of pH and electrolyte upon the mode of particle interaction in homoionic sodium kaolinite suspensions (1977) J. Coll. Interf. Sci., 60 (2), p. 308Reinbold, I., Ulrich, H., Possibilities and limitations of high solids coating colors (1979) Proc. Tappi Coating Conf., p. 31Sanders, N.D., The effect of surface modification of pigments on colloidal stability and structural performance (1992) J. Pulp Pap. Sci., 18 (5), p. 169Sandås, S., Salminen, P., Pigment-cobinder interactions and their impact on coating rheology, dewatering and performance (1991) Tappi J., 74 (12), p. 179Schramm, G., (1994) A Practical Approach to Rheology and Rheometry, , Haake GmbH Publication, KarlsruheScott, W.E., Abbott, J.C., Trosset, S., (1995) Properties of Paper: An Introduction, p. 161. , Tappi Press, AtlantaShaw, D.J., (1980) Introduction to Colloid and Surface Chemistry, p. 208. , Butterworth, LondresStenius, P., Järnström, L., Rigdahl, M., Aggregation in concentrated kaolin suspensions stabilized by polyacrylate (1990) Coll. Surf., 51, p. 219Ström, G., Härdin, A.-M., Salminen, P., A novel approach for improving fibre coverage during blade coating (1995) Nord. Pulp Pap. Res. J., 10 (4), p. 227Swerin, A., (1995) Flocculation and Fiber Network Strength in Papermaking Suspensions Flocculated by Retention Aids Systems, , PhD Thesis, Royal Institute of Technology, StockholmVan Gilder, R.L., Purfeerst, R.D., The effect of coating color solids on properties and surface uniformity (1986) Tappi J., 69 (5), p. 119Verhoeff, J., Hart, J.A., Gallay, W., Sizing and the mechanism of penetration of water into paper (1963) Pulp Pap, Mag. Can., 64, pp. T509Wang, X.Q., Grön, J., Eklund, D., Temperature dependence for adsorption of carboxymethyl cellulose on clay (1996) Proc. Tappi Coating Conf., p. 79Whalen-Shaw, M., Gautam, N., A model for colloidal and rheological characteristics of kaclin latex NaCMC formulations (1990) Proc. Tappi Coating Conf., p. 371Whalen-Shaw, M., Coating structure - Part I: A mechanistic view to the development of wet coaling structure (1989) Proc. Tappi Coating Conf., p. 9Wickman, M., (1998) Surface Chemical Behavior of Alkyd Resins in Offset Printing Inks, , PhD Thesis. Royal Instute of Technology, StockholmYoung, T.S., Fu, E., Associative behavior of cellulosic thickners and its implications on coating structure and Theology (1991) Tappi J., 74 (4), p. 197Zang, Y.-H., Aspler, J.S., The effect of surface binder content on print desnity and ink reciptivity of coated paper (1998) J. Pulp Pap. Sci, 24 (5), p. 14

Paper And Surface Chemistry - Part 1 - Fiber Surface And Wet End Chemistry

The concepts of surface chemistry in papermaking was discussed. Beating, stock prepration, coating and converting process were the steps where surface phenomena plays important role in paper consolidation and performance. The papermaking process included the fundamentals of interactions between fibers and colloids, polymers, minerals and dyes. It was found that surface engineering that was usually applied for metal coating can be applied for fiber surfaces in technological improvement of eucalyptus pulp and paper.193043Beghello, L., (1998) The Tendency of Fibres to Build Flocs, , Doctoral Thesis, Åbo Akademi University, Turku/ÅboBerg, J.C., The importance of acid base interactions in wetting, coating, adhesion and related phenomena (1993) Nord. Pulp Pap. Res. J., 8 (1), p. 75Brinen, J.S., Proverb, R., SIMS Imaging of paper surfaces - Part 2 - Distribution of organic surfactants (1991) Nord. Pulp Pap. Res. J., 6 (4), p. 177Brinen, J.S., The observation and distribution of organic additives on paper surfaces using surface spectroscopic techniques (1993) Nord. Pulp Pap. Res. J., 8 (1), p. 123Brinen, J.S., Greenhouse, S., Dunlop-Jones, N., SIMS (secondary ion mass spectrometry) imaging: A new approach for studing paper surfaces (1991) Nord. Pulp Pap. Res. J., 6 (2), p. 47Buchert, J., Carlsson, G., Vikari, L., Strom, G., Surface characterization of unbleached kraft pulps by enzimatic peeling and ESCA (1996) Holzforschung, 50 (1), p. 69Carlsson, G., (1996) Surface Composition of Wood Pulp Fibers - Relevance to Wettability, Sorption and Adhesion, , PhD Thesis, Royal Institute of Technology, StockholmClark, J.A., (1978) Pulp Technology and Treatment for Paper, p. 48. , Miller Freeman Publications, San FranciscoEverett, D.H., (1989) Basic Principles of Colloid Science, p. 121. , Royal Society of Chemistry, LondonFardim, P., (1999) Surface Chemical Composition of Eucalyptus Kraft Pulp: Caharacterisation and Influences on Strength and Physicochemical Properties of Fibres, , PhD Thesis, Instituto de Química, Universidade Estadual de Campinas, UNICAMP, CampinasFardim, P., Durán, N., Surface properties investigation of unbleached eucalyptus kraft pulp using apparent contact angle measurements (2000) Proc. Third Int. Symp., Workshop Prog. Prod. Process. Cell. Fibers Nat. Polm., ISNaPOL, p. 241Fardim, P., Durán, N., Surface characterisation of unbleached eucalyptus kraft pulp using XPS and TOP-SIMS (2000) Proc. Sixth Europ. Workshop Lignocell. Pulp, EWLP, p. 307Fardim, P., Durán, N., Surface chemical composition and mechanical properties of eucalyptus grandis kraft pulp investigated by XPS and PCA (2001) Proc. 11th Int. Symp. Wood Pulping Chem., ISWPC, 1, p. 305Fardim, P., Holmbom, B., Ivaska, A., Mortha, G., Laine, J., Anionic groups in different pulp fibres (2001) Proc. Seventh Braz. Symp. Chem. Lignins Wood Comp., BSCLW, 2, p. 309Gerly, A., Clémençon, I., The effect of flocculant/microparticles retention programs on floc properties (1999) Nord. Pulp Pap. Res. J., 14 (1), p. 23Hagenhoff, B., High resolution surface analysis by TOF-SIMS (2000) Mikrochim. Acta, 132, p. 259Herrington, T.M., Midmore, B.R., Adsorption of ions at the cellulose aqueous electrolyte interface. 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Ruvo, Marcel Dekker, New YorkLaine, J., Stenius, P., The Effect of ECF and TCF Bleaching on the surface Chemical composition of kraft pulp as determined by ESCA (1996) Nord. Pulp Pap. Res. J., 11 (3), p. 201Laine, J., Buchert, J., Viikari, L., Stenius, P., Characterization of unbleached kraft pulps by enzymatic treatment, potentiometric titration and polylectrolyte adsorption (1996) Holzforschung, 50, p. 208Laine, J., Stenius, P., Carlsson, G., Strom, G., Surface characterization of unbleached kraft pulps by means of ESCA (1994) Cellulose, 1, p. 145Larsson, P.T., Wickholm, K., Iversen, T., A CP/MAS 13C NMR investigation of molecular ordering in celluloses (1997) Carbohyd. Res., 302, p. 19Lindquist, A., Dahlman, O., Characterization of pulp hemicelluloses using MALDI-TOF-SIMS (1998) Proc. Fifth Europ. Workshop Lignocell. Pulp, EWLP, p. 483Lindström, T., Some fundamental chemical aspects on paper forming (1989) Fundamentals of Papermaking, 1, p. 309. , Mechanical Engineering Publishing Ltd., LondonLorenzoni, D.E.D.P., (1998) Lignin Studied by Atomic Force Microscopy, , PhD Thesis, Basle University, BasleMaloney, T.C., Paulapurc, H., The formation of pores in the cell wall (1999) J. Pulp Pap Sci, 25 (12), p. 430Mangelsdorf, C.S., White, R.L., The dynamic double layer, Part 1-theory of a mobile Stern layer (1998) J. Chem. Soc. Faraday T., 94 (16), p. 2441Okamoto, T., Meshitsuka, G., Interpretation of AFM image of kraft pulp (1999) Proc. 10th Int. Symp. Wood Pulping Chem., ISWPC, 1, p. 154Overbeek, J.T., Recent developments in the understanding of colloid stability (1977) J. Colloid Interf. Sci., 58 (2), p. 408Ozaki, Y., Sawatari, A., Surface characterization of a rosin sizing agent in paper by means of EPMA (1997) ESCA and TOF-SIMS. Nord. Pulp Pap. Res. 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Molecular Assembly In Kraft Pulping Of Eucalyptus [organização Molecular Na Polpação Kraft De Eucalipto]

Kraft pulp is a nanostructured material which is produced under chemical degradation conditions where less ordered components are removed and new (supra)molecularly organized systems are created. The effects of kraft pulping on the chemistry of eucalyptus pulp were investigated here by using X-ray Diffraction (XRD), Cross Polarization Magic Angle Spinning Carbon-13 Nuclear Magnetic Resonance (CP/MAS 13CNMR) and Near Infrared Spectrometry (NIR) combined with Principal Component Analysis (PCA). Cellulose, hemicellitloses, uronic acids, lignin and extractive amounts in pulp were determined using either chromatographic or different specific methods. The elastic modulus and tensile strength of pulp hand sheets and fiber morphological parameters such as length, width, cell wall thickness and lumen diameter were also measured. Pulping experiments were conducted varying the active alkali range while temperature, sulfidity, heating rate and liquor-to-wood ratio were kept constant. Two molecular assemblies were suggested and identified as function of active alkali used in pulping. Each molecular assembly had characteristic degree of crystallinity and affected the elastic modulus and tensile strength of the hand sheets. A transition point between the two assemblies was also identified and ascribed to hydrogen bond intermolecular interactions due to removal of lignin, hemicelluloses and bounded water. A mechanism of assembly of cellulose nanofibrils, driven by freeenergy of interaction, was proposed to affect the fibre morphology, decrease fibre wall flexibility and lower inter-fibre bonds. Our results also suggested that the variations in alkali charge usually present in industrial digesters can cause the formation of different molecular assemblies in a very sensitive limit. As a consequence, impacts on mechanical andphysicochemical properties of fibres are expected.68898108Fengel, D., Wegener, G., (1989) Wood: Chemistry, Ultrastructure and Reactions, , Walter de Gruyter, BerlinKlemm, D., Philipp, B., Heinze, T., Heinze, U., (1998) Comprehensive Cellulose Chemistry, 1. , Wiley-VCH, WeinheimDuchesne, I., Daniel, G., The ultrastructure of wood fibre surfaces as a variety of microscopical methods- a review (1999) Nord. Pulp Pap. Res. J, 14, p. 129Atalla, R., Isogai, A., (2005) Polysaccharides: Structural Diversity and Functional Versatility, , Dimitriu, S. ed, Marcel Dekker, New York, Ch 5Wickholm, K., Larsson, P.T., Iversen, T., Assignment of non-crystalline forms in cellulose I by CP/MAS 13CNMR spectroscopy (1998) Carb. Res, 312, p. 123VanderHart, D.L., Atalla, R.H., Studies of microstructure in native celluloses using solid state 13CNMR (1984) Macro molecules, 17, p. 1465E. -L. Huit, P. T, Larsson, T. Iversen, A CP/MAS13C-NMR study of supermolecular changes in the cellulose and hemicellulose structure during kraft pulping, Nord. Pulp. Pap. Res. J. 2001, 16, 46Duchesne, I., Daniel, G., Changes in surface ultrastructure of Norway spruce fibres during kraft pulping visualisation by field emission-SEM (2000) Nord. Pulp Pap Res. J, 15, p. 54Fahlén, J., Salmén, L., Ultrastructural changes in a holocellulose pulp revealed by enzymes, thermoporosimetry and atomic force microscopy (2005) Holzforschung, 59, p. 589Huit, E.-L., Larsson, P.T., Iversen, T., Cellulose fibril aggregation - an inherent property of kraft pulps (2001) Polymer, 42, p. 3309Wickholm, K., (2001), PhD Thesis, Royal Institute of Technology, StockholmEfland, M., Modified procedure to determine acid-soluble lignin in wood and pulp (1977) Tappi J, 60, p. 143Newman, R.H., Hemmingson, J.A., Determination of the degree of cellulose crystallinity in wood by Carbon-13 Nuclear Magnetic Resonance Spectroscopy (1990) Holzforschung, 44, p. 351Segal, L., Creely, J.J., Martin, A.E., Conrad, C.M., An empirical method for estimating the degree of crystallinity using the X-ray difractometer (1959) Text. Res. J, 29, p. 786Tang, H., Belton, P., Ng, A., Ryden, P., 13C MAS NMR studies of the effects of hydration on the cell walls of potatoes and chinese water chestnuts (1999) J. Agric. Food Chem, 47, p. 510Meites, L., (1963) Handbook of Analytical Chemistry, , McGraw-Hill, New YorkRedko, B., Maggion, R., Bugajer, S., A influência da deslignifeacão e do branqueamento na cristalinidade da celulose (1979) O Papel, 3, p. 51Fardim, P., Duran, N., Effects of kraft pulping on the interfacial properties of Eucalyptus pulp fibres (2005) J. Braz. Chem. Soc, 16, p. 91