Properties of oriented strand boards made from some species of bamboo

Abstract

Bamboo is one of lignocellulotic material from non-timber forest product that have great potential as a wood substitution for OSB's raw material. In order to improve physical and mechanical properties of the OSB boards, the bamboo's strands pre-treated by steaming. Steaming pre-treatment was reported could improve dimensional stability and mechanical properties of the boards (Haryadi 2011; Iswanto et al. 2010; Rowell et al. 2002). Adhesive is important element in the manufacture of OSB due to its role as a binder constituent elements of wood. Isocyanate has a lot of advantages, i.e. high reactivity, good bonding strength and high durability, therefore could produce product with high physical and mechanical performance (Kawai et al. 1998). However, its cost that relatively higher than other adhesive based on formaldehyde may limits its utilization in industry. Utilization a mixture of formaldehyde and non formaldehyde adhesive (PF and ISO) with pre-treatment on the strands by steaming was expected contribute on the properties of the boards. In order to determine mechanical properties of the boards, destructive and non-destructive evaluation were taken in this study. The purpose of this study is to develop high quality of OSB that can fulfill the standard in its physical and mechanical properties. The plan of experiments was done by using completely randomized design with two independent variable (Factor A and B). There is also one confounding variable that have no interaction with other variables. Pre-treatment variation (Factor A) is the first factor that consist of 2 levels: steam (a1) and non steam (a2), while the second factor was composition of adhesive on the face, core, and back which consist of 4 levels: 3 layers of strands were bonded by using isocyanate (b1), 3 layers of strands were bonded by using phenol-formaldehyde (b2), face and back layer were bonded by using isocyanate while core layer was bonded by using phenol-formaldehyde (b3), and face and back layer were bonded by using phenol-formaldehyde while core layer was bonded by using isocyanate (b4). Group (C) consist of three different bamboo species, which are bamboo betung (c1), bamboo andong (c2) and bamboo tali (c3). Based on physical evaluation of OSB, the obtained values as follows: density 0.73 – 0.79 gr cm-3; MC 7.19 - 9.53%; TS 24 hours 3.54 – 11.57%; WA 24 hours 21.72 - 39.62%. Whereas from mechanical evaluation was obtained the values as follows: IB 3.52 - 13.82 kgf cm-2, MOR dry // 444 - 925 kgf cm-2, MOR dry ┴ 132 - 256 kgf cm-2, MOR wet // 264 - 612 kgf cm-2, MOR wet ┴ 85 - 187 kgf cm-2 , MOE dry // 50503 - 116044 kgf cm-2, MOE dry ┴ 9436 – 18126 kgf cm-2, MOE wet // 33536 – 9041 kgf cm-2, MOE wet ┴ 6550 – 12839 kgf cm-2. The results of non destructive evaluation (NDE) towards stiffness (MOEd) by using simple regression analysis showed that NDE could not used to estimate Modulus of Elasticity static (MOEs) and Modulus of Rupture (MOR). All parameters evaluated for physical properties of OSB, and almost all parameters for mechanical properties fulfill the standards set out in CSA 0437.0 (Grade 0-2), except MOE dry // from bamboo tali's strand with adhesive PF, combination PF/ISO/PF; MOE dry ┴ from bamboo betung's and andong's strand with adhesive PF, combination PF/ISO/PF ; and almost all OSB product from bamboo tali's strand except those that using ISO.