Fiber Evolution during Alkaline Treatment and Its Impact on Handsheet Properties

A1 Journal article (refereed)

Internal Authors/Editors

Publication Details

List of Authors: Yun Ji, Yangyang Peng, Anders Strand, Shiyu Fu, Anna Sundberg, Elias Retulainen
Publisher: College of Natural Resources at North Carolina State University
Place: North Carolina
Publication year: 2018
Journal: BioResources
Volume number: 13
Issue number: 4
Start page: 7310
End page: 7324


To understand the swelling effects of alkaline treatment on the
morphological properties of fibers and physical properties of
handsheets, bleached softwood kraft pulp was treated with NaOH at
different concentrations. The results showed that the fiber swelling
increased, but the shrinkage and elongation of the paper at a NaOH
concentration of 6% or higher did not improve. Dissolution of amorphous
material occurred during the treatment together with peeling reactions.
The fiber length and shape factor decreased and the fines content
increased with an increasing alkali concentration. The cellulose
crystallinity decreased with an increasing NaOH concentration. This was
confirmed by X-ray diffractometry, which also showed that some cellulose
I was converted to cellulose II, especially at higher NaOH
concentrations (> 9%). The fiber curl and kink indices increased and
the handsheet density decreased with an increasing NaOH concentration.
However, the tensile index decreased more steeply than the density with
an increasing NaOH concentration, possibly because of the lower number
and strength of the interfiber bonds, increased kinks, and reduced fiber
strength and length. The handsheet extensibility first increased and
subsequently decreased as the NaOH concentration increased, which
indicated that well-controlled NaOH treatment could be used to improve
the extensibility of paper.


Alkaline, Cellulose, Elongation, Fibres, Handsheet properties, strength


Last updated on 2019-21-01 at 05:12