Title
Upgrading of paper from mixed office waste paper pulp by blending with virgin softwood kraft pulp for tropical conditions
Authors
NISHI K. BHARDWAJ

Received October 18, 2024
Published Volume 59 Issue 3-4 March-April
Keywords recycled paper, mixed office waste paper, blending, papermaking properties, physical strength, univariate regression

Abstract
Pulp blending, one of the methods for restoring the strength of secondary fibres, is the focus of this study, utilizing virgin softwood kraft pulp as the strength enhancing material. A series of blending experiments were conducted by adding 0 to 25% virgin pulp, with varying freeness levels (610-320 CSF), to mixed office waste (MOW) pulp to produce high-quality paper. The physical and mechanical strength properties of the paper, including density, tensile, burst, and tear strengths, were measured. The strength of various pulp blends increased significantly compared to MOW pulp, and pulp drainage also improved when the freeness of the virgin pulp was higher than that of the MOW pulp. By replacing inactive secondary fibres with active virgin fibres, physical strength was enhanced due to improved interfibre bonding. Additionally, second-order univariate polynomial regression models were developed based on the experimental results.