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A simulated study on some fundamental aspects in flakeboard manufacture

University of British Columbia

The localized properties of conventional pressed flakeboards were studied using simulated approaches. There parallel experiments were performed in this study. Firstly, Columns of trembling aspen flakes were assembled and pressed in wood particle mat in order to simulate localized variations in a flakeboard. The flake columns were constructed from 24, 32, 40 microtomed flakes. Powdered phenol formaldehyde resin was applied to all flakes at the loading level of 1%. The flake assemblies were assessed in term of bonding properties and dimensional stability. The thickness swell test were performed using an image analysis system Three variables were studied (1) pressing condition; (2) number of flakes in a flake assembly (density levels); (3) vertical layers in each flake assembly. Secondly, the compression process of the flake columns were also monitored the deformation process of the flake columns were also monitored using stress and strain relationships using a computerized cold press. The deformed wood structures were observed using a scanning electron microscope. The dimensional properties of flakes compressed at different compaction ratios were also tested. Thirdly, the flow properties of the powdered phenol formaldehyde resin was studied using a thermal mechanical analyzer (TMA). A range of pressing forces and heating rates were applied to simulate internal environmental conditions in flakeboard. The results show that density of flake assemblies influences heat transfer, and also positively affects bonding strength at the intermediate and core layers and thickness swell values the face, intermediate and core layers. Outer layers generally have greater bonding strength and thickness swell values than inner layers did. Moisture content affects bonding strength and thickness for higher density flake assemblies at the face and intermediate layers. This results from compression tested show that, at a higher CR, the thickness swelling was mainly contributed to the balloon back of the cell lumens when compressed wood was soaked in water condition. The results from (TMA) studies show that pressure and heating rate affect adhesive flow and greater adhesive flow occurred at the more rapid heating rates.

Thesis/Dissertation

application/pdf

2009-02-02

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http://hdl.handle.net/2429/4092

Forestry

University of British Columbia

UBCV

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