The effects of a two stage heat treatment process on the properties of particleboard

Abstract

Steam pre-treatment can effectively improve the dimensional stability of panel products such as particleboard and fiberboard. At temperatures above 200-210 degrees C steam pre-treatment might result in a significant reduction of the bond strength of the panel product. The results of an effective two stage heat pre-treatment process, in which treatment temperatures below 200 degrees C are used, are given in this paper. The variations in process conditions which affect the particleboard properties are described in detail. A two-stage heat pre-treatment with temperatures below 200 degrees C appears to improve the dimensional stability of panel products. The process conditions used have an effect on thickness swelling and internal bond properties of the particleboard prepared, especially during the first process stage (hydrothermolysis). The best results were obtained with wood particles which were only thermolysed (without curing)

Physical Properties of Boards Manufactured with Hygrothermally Treated Tepa (Laureliopsis Philippiana Looser) Particles

“…A decrease of water absorption from 97.4 % to 60.9 % after 2 hours and from 115.7 % to 75.5 % after 24 hours was determined. This trend is in agreement with results reported by Tomek (1966), Boonstra et al (2006) and Poblete and Peredo (1990). The increase in the amount of extractable hydrophobic compounds and the reduction in wettability in treated L. philippiana particles determined by Crespo et al (2013), could explain the changes in the physical properties.…”

“…Utjecaj toplinske obrade iverja na fi zikalna svojstva ploča Tomek (1966) states that thermal treatment of the particles decreases adsorption properties, resulting in a decrease in thickness swelling of 45 % to 50 % in particleboards manufactured with treated particles and UF. Boonstra et al (2006) indicate that hygrothermolysis has a positive effect on thickness swelling, and hence thermal treatment of the wood before the manufacturing process could improve the dimensional stability of the particleboards. Thermal treatment reduces wood contraction and swelling, improving its dimensional stability (Cao et al, 2012).…”

Use of alkyl ketene dimer (AKD) for surface modification of particleboard chips

“…This can be explained by the formation of formic and acetic acid during the curing step (Roffael 1989). The acidity leads to the decomposition of carbohydrates, thus, to shear strength reduction (Boonstra et al 2006) and promotes the hydrolysis of the UF-resin (Myers 1983). In comparison to controls (CO), the addition of paraffin (PAR bl) and AKD (AKD bl) to the glue reduced the internal bond strength by 9 and 24%, respectively.…”

“…5% after 24 h as compared to control boards that revealed 17%. Several researchers reported that heat-treatment of particles leads to enhanced dimensional stability (Tomek 1966, Tomimura and Matsuda 1986, Boonstra et al 2006). In addition, numerous studies on chemical modification have demonstrated that an alteration of the wood cell wall structure can strongly increase the water resistance of particleboards.…”

Propriedades De Painéis Aglomerados Submetidos Ao Tratamento Térmico

“…Unsal et al (2006), showed that temperatures above 200°C improve the dimensional stability of particleboard. Boonstra et al (2006), showed that heat treatment with temperatures below 200 o C has a potential to improve the dimensional stability of wood panels. However, Sekino et al (2005), reported a significant reduction of the bond strength of particleboard in this range temperature.…”