Selected Chemical Modifications of Red Oak and Hard Maple Flakes for Flakeboard Manufacturing

Abstract

The feasibility of using low chemical concentrations, time, and pressure for modifying red oak and hard maple flakes was investigated. Red oak and hard maple flakes were pretreated with water, sodium hydroxide, and acetic acid for different times and pressures to determine weight loss. The chemically modified flakes were processed into flakeboards. Untreated aspen, red oak, and hard maple panels were used as controls. Compared to the hard maple controls, hard maple panels had a reduction in press closing time for all treatment levels. However, a reduction in press closing time for treated red oak compared to red oak controls was evident only for very high weight loss values. Weight loss for red oak and hard maple can be controlled, and it appeared that acetic acid treatments produced better properties for both species compared to sodium hydroxide or water treatments. Mechanical properties were reduced in hard maple for all treatments and in red oak for some treatments, particularly sodium hydroxide treatments. Bending strength values for acetic acid-treated red oak panels were not significantly different from red oak control values. Water and acetic acid treatments for red oak produced similar dimensional stability values compared to red oak controls. This indicated that weight loss can be controlled without detriment to the dimensional stability of the panels. Density, internal bond, thickness swell, water absorption, and linear expansion values for red oak control and acetic acid-treated red oak panels compared favorably with aspen control panels. Density, internal bond, thickness swell, water absorption, and linear expansion values for hard maple control and linear expansion values for water and acetic acid-treated hard maple panels also compared favorably with aspen control panels.