Reactive maleic anhydride polyolefins (MAPOs) in oriented strand board. Part 2: Influence on physical and mechanical properties

Abstract

Abstract The use of reactive polyolefin and phenol formaldehyde (PF) resin blends to improve the moisture durability of oriented strand composite (OSC) panels was investigated. Test panels were hot pressed with adhesive blends consisting of varying proportions of PF and maleic anhydride polypropylene (MAPP) anionic emulsion, and their physical and mechanical properties were evaluated. The addition of MAPP did not significantly affect the modulus of elasticity (MOE) of the panels, but reduced the modulus of rupture in bending (MOR) for 12% moisture content (MC) and 24-h soak specimens. An increase in PF content significantly improved the MOE and MOR of specimens subjected to the environment. Adding MAPP reduced internal bond strength, particularly at higher PF levels. The addition of MAPP and raising PF levels significantly reduced water absorption and thickness swelling of the panels. At higher MAPP levels, the water vapor transmission in OSC as well as the permeance of the material, was reduced. Composite board equilibrated to lower MC with increasing MAPP content in the resin blend. The results indicate that increasing the PF content is the most effective method of improving both moisture resistance and the mechanical properties of OSC; addition of MAPP improves the moisture resistance of the panels, but significantly reduces their mechanical properties.