ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Influence of recycling and temperature on the swelling ability of paper

Erika Letková, Michal Letko, and Milan Vrška

Department of Chemical Technology of Wood, Pulp and Paper, Faculty of Chemical and Food Technology, Slovak University of Technology, Radlinského 9, 812 37 Bratislava, Slovakia

E-mail: erika.novakova@stuba.sk

Abstract: Hornification is the loss of fiber wall swelling which is detrimental to subsequent recycling resulting from drying. It is known that dried fibers lose their conformability and swelling capacity. The effect of recycling treatment on the swelling ability of hardwood bleached kraft pulp fibers was determined. Modelling paper recycling, sheets were recycled using heat treatment (23°C, 60°C, 100°C). The results were compared with those for natural fibers from bleached kraft pulp. Swelling kinetics of sheets was measured by a modified method monitoring interactions of pulp with water. Swelling ability decreased during the recycling in comparison with never-recycled pulp at all temperatures. Recycling of sheets caused only small changes in the cupri-ethylene-diamine viscosity, however, the water retention value decreased considerably.

Keywords: hardwood bleached kraft pulp – recycling – swelling kinetics – hornification – heat treatment

Full paper is available at www.springerlink.com.

DOI: 10.2478/s11696-011-0089-z

Chemical Papers 65 (6) 822–828 (2011)