Physical and mechanical properties of hydrothermally modified Pinus caribaea Morelet wood

Abstract

Dimensional changes in wood during service are a major threat to its longevity in service. This study therefore examined the effect of hydrothermal treatment on selected physical and strength properties of Pinus caribaea wood. Bolts were obtained from five Pinus caribaea trees at the tree’s top, middle, and basal positions. Each of the bolts was processed into test dimensions and hydrothermally treated at 100°C, 120°C, and 140°C for 1 and 2 hours, while some sets were untreated. The treated and untreated wood were evaluated for their density, water absorption (WA), longitudinal, tangential, radial, and volumetric swellings (LS, TS, RS and VS, respectively), compression strength parallel (MCS//) and perpendicular to grain (MCS┴). The data were subjected to analysis of variance at α= 0.05. The results reveal that the reduction in density was not significant after treatment, while the WA generally reduced after treatment, with the least observed at 100-1hr (96.25%). The LS was highest (0.58%) at 120-2hr and least (0.29%) at 140-1hr. The RS was significantly reduced to 4.78% at 120-2hr while TS had the significantly least value at 100-1hr (6.94%). The VS was significantly reduced to 12.17% at 140-2hr, while the highest value was found in the untreated samples (17.43%). The highest (53.68N/mm²) and least (48.25N/mm²) MCS// was observed in untreated wood and wood treated at 100-2hr, while the MCS┴ was significantly reduced at 120-1hr (100.65N/mm²). Hydrothermal treatment of P. caribaea at 100°C and 140°C for 1-2hours is capable of significantly enhancing its dimensional stability while preserving its mechanical integrity.