Improving the wet tensile strength of recycled paper by increasing its bond capacity

This research relates to the cellulosic fibres of treated deinked Mixed Office Waste (MOW) paper and is directed particularity to a method for improving the wet strength of recycled paper. The effect of chemical treatment of fibre was investigated. Fibres were treated with 6 and 10% Succinic Acid (SA), with 3% and 5% catalysts (based on the total weight of fibres). The catalysts used for this research were Sodium di-hydrogen Phosphate (SDHP) and Sodium hypophosphite (SHP). Additionally, 0% and 1% cationic polymeric resin or Anionic Trash Catcher (ATC) and 2% wet strength resin or Poly Aminoamide-Epichlorohydrin (PAE) were used to treat fibres. All of the handsheets, including the control handsheet, were treated with 2% PAE. The chemical structure of those fibres treated with Succinic Acid and catalysts was investigated by XRD and FTIR analyses. Results of these treatments showed that the wet tensile strength of paper improved by this treatment and tensile properties optimised at 10%SA, 5%SDHP and 1%ATC. Chemical treatment had an effect on the crystallinity index and crystallite size of fibres. X-ray diffractometer demonstrated that the crystallinity index decreased when compared to untreated pulp. FTIR analysis showed that carboxyl groups were slightly increased in treated fibres.