The glueline shear strength of Peronema canescens and Acacia hybrid

Abstract

The glueline shear strength is one of the common measures used to estimate potential performance of bonded wood joints. This study was conducted to determine the glueline shear strength of Pernonema canescens (Sungkai) and Acacia hybrid (A. hybrid). The wood were bonded with polyvinyl acetate (PVAc) and Emulsion Polymer Isocyanate (EPI) and these are for dry use in non-structural timber production. Sungkai and A. hybrid logs were obtained from Telipok and Ulu Kukut, Sabah respectively, were debarked, sawn and air-dried prior to being sawn to 20 mm thick, 60 mm wide and 150 mm long. After reaching the constant moisture content, the gluing process was carried out. 2 types of adhesives were used; EPI and PVAc. The glue was spreaded at a constant spreading rate of 200 g/m2. 3 types of assembly combinations were made; Sungkai-Sungkai, A. hybrid-A. hybrid and Sungkai-A. hybrid. The assemblies were clamped for 24 hours, as recommended by the glue manufacturer. The test specimen preparation and the glueline shear strength test was conducted in accordance with the Manual for Testing Methods for Plantation Grown Tropical Timbers (Finger and Laminate Joints in Non-Structural Timber Production). The results showed that, the average glueline shear strength of Sungkai-Sungkai, A. hybrid-A. hybrid. and Sungkai-A. hybrid bonded with EPI are 7.48 N/mm2, 6.58 N/mm2, 6.87 N/mm2 respectively. While the average glueline shear strength of Sungkai-Sungkai, A. hybrid-A. hybrid and Sungkai-A. hybrid bonded with PVAC are 7.61 N/mm2, 6.03 N/mm2, 7.60 N/mm2 respectively. Based on the results obtained, the glueline shear strength for all assembly combinations exceed the minimum requirement of the shear strength for laminate joints, which is 5.32 N/mm2. Thus, Sungkai and A. hybrid wood have the potential to serve as supplemental raw material for the non-structural timber production.