Dinesh Fernando & Geoffrey Daniel CRUW COST FP1105 Workshop, Coimdra Morphological Ultrastructural Characteristics of Fines Fraction Produced during HC and LC refining of TMP for Fundamental Understanding of Property Development Dinesh Fernando & Geoffrey Daniel Center for Research on Ultrastructure of Wood Fibers (CRUW) Dept. of Forest Products Swedish University of Agricultural Sciences (SLU) Uppsala, Sweden. 08 May 2014 Dinesh Fernando 1

Results and Discussions CRUW Results and Discussions Morphological characteristics of fines produced during HC and LC refining 40 µm Primary pulp fines Similar properties between HC & LC pulps; - tensile index (~40 Nm/g), - density (398 kg/m3), - light scattering (59 m2/kg) But with a lower energy (20%) from LC refining HC Fines LC Fines A considerable differences in ultrastructural characteristics between HC & LC Fines - Arrowheads; broader fibrils - Arrow; String-like - Arrows; Flake-like 08 May 2014 Dinesh Fernando 2

Results and Discussions CRUW Results and Discussions HC fines A wide variation in the morphology; - predominantly ribbon-type fibrils from S2 layer - ranging from narrow string-like to broad sheet-like fibrils - broad cellulose fibrils possess high bonding potential and explain high density and strength properties - SL=sheet-like fibrils, LS=lamellar sheets LC fines Marked by very narrow strings- or thread-like ribbons; - good scattering structures (1-7) - provide required porous structure (a-g) for better light scattering Lacked broader fibrils such as LS and SL and explain lower strength compared to HC pulps 2 µm 0,5 µm 08 May 2014 Dinesh Fernando 3

Thank you ! Acknowledgments CRUW COST Action Workshop, Edinburgh Acknowledgments Dmitri Gorski (now at Metso, Sweden) from Norske Skog, Halden, Norway. Financial support to CRUW (Centre for Research on the Ultrastructure of Wood Fibers) from VINNOVA, Eka Chemicals, Holmen, SCA, Smurtfit Kappa, Stora Enso & Södra Cell is gratefully acknowledged. Thank you ! Center for Research on Ultrastructure of Wood Fibers Dept. of Forest Products Swedish University of Agricultural Sciences Uppsala, Sweden. 08 May 2014 Dinesh Fernando 4