Procedural influence on the properties of particleboards made from AKD modified chips

Abstract

Wood chips were treated with alkyl ketene dimer (AKD) using three different processes to impart water resistance to particleboards. In the first process, AKD was blended with UF resin. Thickness swelling and water uptake after a 24 h immersion period (20 and 69%) were lower than in the control boards (28 and 81%) but were higher than in the paraffin references (10 and 22%). In process 2, AKD and UF resin were sprayed separately on the chips resulting in a greater reduction of thickness swelling (15%) and water uptake (49%) than in process 1. Paraffin references revealed a thickness swelling and water uptake of 7 and 25%, respectively. An extension of the pressing time in processes 1 and 2 did not increase water repellence. In process 3, particleboards were made from AKD-treated chips that were cured at 130• C (24 h) prior to gluing. They showed a thickness swelling of 7% and a water uptake of 25%, whereas particleboards with paraffin exhibited levels of 8 and 29%. The thickness swelling and water uptake of boards with AKD increased when the curing time was reduced from 24 to 12 to 6 h (130 • C). Changing the curing temperature from 130 to 100• C (12 h) had no effect on board properties. The IB of boards made from pre-cured chips with AKD (24 h/130• C) was 44% lower than in controls and 35% lower than in paraffin references. This indicates that AKD impedes the adhesion.

Modification of Chinese Fir with Alkyl Ketene Dimer (AKD): Processing and Characterization

“…AKD has been widely used as a sizing agent in papermaking (Chen and Biermann 1995;Asakura et al 2006;Lindstrom and Larsson 2008). For wood modification, most previous studies have focused on the hydrophobization of wood surfaces using emulsified AKD mixture (Antti-Korpela 2009; Kukkonen et al 2010), treatment of thermally modified wood with AKD solution (Laitinen et al 2005), or making particleboard from AKD-modified chips (Hundhausen et al 2009). Compared with anhydride, epoxide, chlorosilane, alkyl chloride, or aldehyde, AKD is a very mild chemical, and the involved solvents are recyclable.…”

PF-bonded particleboards from AKD-modified chips

“…• C (6, 12, and 24 h) prior to pressing (Hundhausen et al 2009b). The main disadvantage was that the increased dimensional stability was associated with strongly reduced internal bond strength (IB).…”