Effects of Tree Species and Wood Fiber Size in the Core Layer on the Formaldehyde Emission of Three-Layers Fiberboard

Abstract

Three-layered medium density fiberboards (MDFs) were produced using fine wood fibers in the face layers and coarse wood fibers in the core layer. The core layer were produced from pine wood fiber or beech wood fibers while the face fibers were produced pine fibers. The length of the beech fibers in the core layer increased from 4.3 mm to 28.2 mm while it increased from 4.9 to 29.1 mm for the pine fibers. The shelling ratio and panel thickness were 50/50 and 10 mm, respectively. Based on EN 120-method, the formaldehyde emission released from the MDFs were identified. The formaldehyde emission considerably declined with increasing fiber size at the same manufacturing parameters such as resin content, density, pressing parameters, and mat moisture content. Furthermore, MDF specimens having beech fibers in the core layer showed lower formaldehyde emission than that of the MDFs having pine fibers in the core layer.