ENHANCING THE PHYSICO-MECHANICAL PROPERTIES OF PHILIPPINE BAMBOOS THROUGH SPENT COOKING OIL HEAT TREATMENT

Abstract

Thermal modification (TM) through spent cooking oil heat treatment (SCOHT) was applied to giant bamboo (Dendrocalamus asper (Schult.) Backer) and kauayan-tinik (Bambusa spinosa Roxb.) to evaluate their physico-mechanical properties. Bamboo samples underwent SCOHT at 175°C and 200°C for 30 min and 60 min using a fabricated laboratory boiling vat. SCOHT significantly reduced moisture content (MC) from 11.10% (control) to 3.97% (200°C-30 min), and relative density (RD) from 0.70 (control) to 0.58 (200°C-60 min). Thickness swelling (TS) and water absorption (WA) were reduced by up to 79% and 69%, respectively. Water contact angle (CA) increased from 62.88° (control) to 81.75° (200°C-60 min), indicating enhanced hydrophobicity. Meanwhile, the mechanical properties, particularly the modulus of rupture (MOR) and modulus of elasticity (MOE), were not significantly affected. B. spinosa exhibited higher values than D. asper in terms of RD (0.66 vs. 0.59), MOR (147.31 MPa vs. 122.43 MPa), and MOE (16.28 GPa vs. 12.00 GPa), but lower TS (1.82% vs. 2.45%) and WA (13.30% vs. 17.00%). These findings suggest that SCOHT enhances the bamboos’ dimensional stability and water resistance without compromising their bending properties. The increased hydrophobicity poses considerations in bamboo composite production, particularly on surface energy activation and adhesive selection.