Durability of pine strandboard modified with low molecular weight phenol formaldehyde

A continuing challenge for wood and wood-based composite building materials has been durability--the power of resisting agents or influences which tend to cause changes, decay, or dissolution; lastingness. In the case of wood-based products, this often requires a resistance to biological degradation and moisture related dimensional instability (particularly in particle and flake or strand boards). Borden Chemical Company has developed a new low molecular weight phenol formaldehyde additive, PD-112, to improve durability in composite wood products. This study investigated PD-112’s contribution to durability in oriented strand board (OSB) through laboratory testing of treated southern pine strandboard panels versus untreated control panels. Tests examined mechanical properties, as well as resistance to degradation by water infiltration, mold, decay fungi and termite attack. PD-112 treatment significantly reduced moisture induced thickness swelling without adverse effects on strength properties. Modulus of rupture (MOR) and modulus of elasticity (MOE) increased somewhat, while internal bonding strength (IB) increased greatly with increasing PD-112 treatment. PD-112 imparted good termite resistance to pine strandboard. Treatments gave excellent resistance to decay by selected brown rot fungi, and moderate resistance to growth of selected mold fungi