Effect of strand combination on dimensional stability and mechanical properties of oriented strand board made from tropical fast growing tree species

Abstract

The objective of this research was to evaluate the effect of strand combination on dimensional stability and mechanical properties of OSB made from Paraserianih.es falcataria (P), Maesopsis eminii (M) and Acacia mangium (A) woods. Three-layered OSBs bonded with 7% Methylene di-isocyanate (MDI, Type H3M) resin with the core layer orientation perpendicular to the face and back layers. The strand composition for face, core and back was 25, 50 and 25%, respectively. Nine strand combinations consisting of 3 homogenous boards (i.e., PPP, MMM and AAA) and 6 mixed boards (i.e., PMP, PAP, MPM, MAM, AMA and APA) were tested. The results indicated that OSB manufactured from strands with lower density (PPP board) had lower dimensional stability (water absorption and thickness swelling). Boards prepared from a mixture of lower density strands and higher density strands (PMP and PAP combinations) had better dimensional stability. The OSB manufactured from higher density strand (AAA) had lower modulus of rupture and modulus of elasticity values, the values increased by mixing strands with lower density strands into AMA and APA boards. All parameters of OSB evaluated in this experiment met the requirement of CSA 0437.0 standard for grade O-l OSB panels, exception was observed for TS value of APA board. Strands combination resulted in typical density profiles. OSB manufactured from lower density strands set in the core layer showed a steeper density profile and OSB manufactured from higher density strands set in the core layer showed a more uniform density profile. © 2010 Asian Network for Scientific Information.