Swelling Of Recycled Wood Pulp Fibers: Effect On Hydroxyl Availability And Surface Chemistry


  • William T. Tze
  • Douglas J. Gardner


Recycled fiber, swelling, surface chemistry, hydroxyl group, fiber hornification


The objective of this research was to examine how swelling treatments affect the hydroxyl availability and surface chemistry of recycled fibers. It also assessed the use of organic liquids in mitigating fiber hornification, the loss of hydrogen-bonding ability in recycled fibers. Hardwood bleached kraft pulp fibers were recycled, swollen, and subsequently analyzed for water retention value (WRV), dynamic contact angle, and hydroxyl number. Results show that the relative swelling powers of the liquids were: 12% NaOH > formamide > dimethyl sulfoxide = 2% NaOH = ethylene glycol. These liquids resulted in WRVs that were 23-72% higher than the control, i.e. the water-swollen recycled fibers (WRV 1.10). Swelling increased the hydroxyl number of the fibers except for those treated with 12% NaOH. Fibers that were swollen to a greater extent had a higher total surface-free energy and a lower water contact angle. By swelling the fibers in organic liquids, polar surface-free energy increased with an increase in hydroxyl numbers. Such a relationship was obscured for the alkaline treatments, which presumably altered the chemical composition of the fibers. These findings promote understanding for a more effective formulation of treatment methods for recycled fibers. An immediate implication from this study is the strong fiber swelling power of formamide whose concentration and cost efficiency should be optimized in future studies.


American Society For Testing And Materials. (ASTM) 1996. ASTM Standard D 4274-94. Standard test methods of testing polyurethane raw materials: Determination of hydroxyl numbers of polyols. Philadelphia. PA.nAnonymous. 1997. Properties of common laboratory solvents. Pages 15-14-15-18 in D. R. Lide, ed. Handbook of chemistry and physics 78th ed. CRC Press, New York, NY.nAnonymous. 2000. Chemical prices ending October 27, 2000. Chemical Market Reporter 258(18):38-46.nAtalla, R. H. 1992. Structural changes in cellulose during papermaking and recycling. Pages 229-236 in R. M. Rowell, T. L. Laufenberg, and J. K. Rowell, eds. Materials interactions relevant to recycling of wood-based materials. Proc. Materials Research Society Symposium, vol. 266. Materials Research Society, Pittsburg, PA.nBerg, J. C. 1993. The importance of acid-base interactions in wetting, coating, adhesion, and related phenomena. Nord. Pulp Pap. Res. J. 1:75-85.nCorte, H., H. Schaschek, and O. Broens. 1957. The rupture energy of paper and its dependence on stress-time characteristics during drying. Tappi 40(6):441-447.nFengel, D., And G. Wegener. 1984. Wood chemistry, ultrastructure, reactions. Walter de Gruyter, New York, NY. 613 pp.nFreeland, S. A., And B. F. Hrutfiord. 1994. Caustic treatment of OCC for strength improvement during recycling. Tappi J. 77(4):185-191.nGardner, D. J., W. T. Tze, And S. Q. Shi. 1999. Surface energy characterization of wood particles by contact angle analysis and inverse gas chromatography. Pages 263-293 in D. S. Argyropoulos, ed. Advances in lignocellulosics characterization. TAPPI Press, Atlanta, GA.nHodgson, K. T., And J. C. Berg. 1988. Dynamic wettability properties of single wood pulp fibers and their relationship to absorbency. Wood Fiber Sci. 20(1):3-17.nHoward, R. C. 1990. The effects of recycling on paper quality. J. Pulp Pap. Sci. 16(5):J143-J149.nJacob, P. N., And J. C. Berg. 1993. Contact angle titration of pulp fiber furnishes. Tappi J. 76(5):133-137.nKatagiri, T., And T. Maekawa. 1991. Influence of solvents on the structure of SiO2 gel from hydrolysis of tetramethylorthosilicate. J. Non-Cryst. Solids 134:183-190.nKatz, S., N. Liebergott, And A. M. Scallan. 1981. A mechanism for the alkali strengthening of mechanical pulp. Tappi 64(7):97-100.nKim, N.-H., J. Sugiyama, And T. Okano. 1993. Alkaliswollen structures of native cellulose fibers. Pages 75-80 in J. F. Kennedy, G. O. Phillips, and P. A. Williams, eds. Cellulosics: Chemical, biochemical and material aspects. Ellis Horwood, New York, NY.nKlungness, J. H., And D. F. Caulfield. 1982. Mechanisms affecting fiber bonding during drying and aging of pulp. Tappi J. 65(12):94-97.nLiu, F. P., M. P. Wolcott, D. J. Gardner, and T. G. Rials. 1994. Characterization of the interface between cellulosic fibers and a thermoplastic matrix. Composite Interfaces 2(6):419-432.nLiu, F. P., M. P. Wolcott, T. G. Rials, And J. Simonsen. 1998. Relationship of wood surface energy to surface composition. Langmuir 14(2):536-541.nMantanis, G. I., And R. A. Young. 1997. Wetting of wood. Wood Sci. Technol. 31:339-353.nMantanis, G. I., And R. M. Rowell. 1995. Swelling of compressed cellulose fiber webs in organic liquids. Cellulose 2: 1-22.nMcKenzie, A. W., And H. C. Higgins. 1955. The structure and properties of paper: III. Significance of swelling and hydrogen bonding in interfiber adhesion. Austral. J. Appl. Sci. 6:208-217.nNayer, A. N., And R. L. Hossfeld. 1949. Hydrogen bonding and the swelling of wood in various organic liquids. J. Amer. Chem. Soc. 71:2852-2855.nQin, X., And W. V. Chang. 1995. Characterization of polystyrene surface by a modified two-liquid laser contact angle goniometry. J. Adhesion Sci. Technol. 9(7):823-841.nRobertson, A. A. 1964. Cellulose-liquid interactions. Pulp Paper Mag. Canada 65:T171-T178.nRobinson, J. V. 1980. Fiber bonding. Pages 915-963 in J. P. Casey, ed. Pulp and paper chemistry and chemical technology. vol. 2, 3rd ed. John Wiley & Sons, New York, NY.nRodriguez, F. 1982. Principles of polymer systems. Hemisphere Publishing, New York, NY. 575 pp.nStamm, A. J. 1964. Wood and cellulose science. Ronald Press, New York, NY. 549 pp.nTechnical Association Of The Pulp And Paper Industry. (TAPPI) 1991. TAPPI Useful Method UM 256. Water retention value. Atlanta, GA.nThode, E. F., And R. G. Guide. 1959. A thermodynamic interpretation of the swelling of cellulose in organic liquids: the relations among solubility parameter, swelling, and internal surface. Tappi 42(1):35-39.nTze, W. T., And D. J. Gardner. 2001. Contact angle and IGC measurements for probing surface-chemical changes in the recycling of wood pulp fibers. J. Adhesion Sci. Technol. 15(2):223-241.nVan Oss, C. J., M. K. Chaudhury, And, R. J. Good. 1988. Interfacial Lifshitz-van der Waals and polar interactions in macroscopic systems. Chem. Rev. 88:927-941.nWilhelmy, J. 1863. Über die Abhängigkeit der Kapillaritäts-Konstanten des Alkohols von Substanz und Gestalt des benetzten festen Körpers. Ann. Physik. 119: 177-217. Cited by Hodgson and Berg. 1988.n






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