Weatherability of Phenolic-Bonded Ghanaian Hardwood Flakeboard Made from ACA-Treated Flakes

Ring flakes manufactured from a chip mixture of 22 Ghanaian hardwood species in equal weight proportions were treated to four retention levels (0.0, 0.2, 0.4, and 0.6 pcf or 0.0, 3.2, 6.4, and 9.6 kg/mi) of ammoniacal copper arsenite (ACA) to manufacture phenolic-bonded structural-type particleboards of 5 and 8 percent resin solids. Samples were subjected to a control test condition and vacuum-pressure-soak-dry (VPSD) and ASTM accelerated aging (AA) weathering tests. All panel types (all preservative level and resin content combinations) readily met the MOR, MOE, and IB minimum requirements, and the requirement of no more than 50 percent MOR loss after AA specified by Commercial Standard CS 236-66 for type 2B2 particleboard. For both resin levels, MOR and IB of the nonweathered panels were reduced no more than 15.3 and 17.0 percent, respectively, by the addition of preservative. MOE of non-weathered panels was reduced by the addition of preservative only at the 5 percent resin level by no more than 8.4 percent. The percent loss of MOR, MOE, and IB by weathering averaged significantly less at the 8 percent resin level. Incremental MOR losses of 4 or 5 percent per 0.2-pcf increase in preservative level occurred, respectively, In boards subjected to VPAD or AA. Irreversible thickness swelling (ITS) was increased by the addition of preservative, but essentially was independent of preservative level. ITS also was less with 8 percent resin. Irreversible linear expansion (ILE) was negative in all panel types, but less shrinkage occurred in treated panels and/or panels with 5 percent resin content. ILE was independent of increases on preservative level.

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