Recycled CCA-treated lumber in flakeboards: Evaluation of adhesives and flakes

FIakeboards were produced from recycled chromated copper arsenate (CCA) tre ated and untreated southern pine (Pinus spp.) using two adhesives and two c ommon flaking techniques. The adhesives employed were polymeric methylene d iphenyl diisocyanate (pMDI) and liquid phenol-formaldehyde (LPF). Ring and disc flakes were evaluated. All panels were tested for physical properties (thickness swelling (TS) and water absorption (WA)) and mechanical properti es (internal bond (IB), modulus of elasticity (MOE), and modulus of rupture (MOR)). CCA-treated boards, especially ring-flaked ones, exhibited lower o verall performance for the physical and mechanical properties tested than t he untreated controls. PMDI- and LPF-bonded boards had similar mechanical p roperties (MOR and MOE) but pMDI-bonded boards had significantly higher phy sical properties and IB values. Boards bonded with 2 percent pMDI displayed significantly better IB values than boards prepared with 3 and 4 percent L PF. The improved physical properties and IB strengths of boards made with p MDI adhesive indicate a potential opportunity for manufacturing structural flake-boards from recycled CCA-treated lumber.