Effects of superheated steam treatment on properties of light red meranti and kedondong

Light red meranti (Shorea spp.) and kedondong (Canarium spp.) are known to be non-durable and dimensionally unstable. Due to the aforementioned matters, a proper treatment is required to enhance the properties of these woods. Heat treatment is one of the potential methods to solve the problems of these materials. A study was undertaken to determine the effects of superheated steam (SHS) treatment on the performance of light red meranti and kedondong woods and to optimise its parameters for optimum biological, physical and mechanical properties of these woods using response surface methodology (RSM). The range of treatment temperature and time studies were between 172 to 228 °C and 95 to 265 min respectively. Air-dry samples with nominal dimensions of 410 mm long × 25 mm wide × 25 mm thick were proposed in this study. An oven equipped with a boiler and heater to produce a SHS was used to heat the samples. The response analysis such as resistance against white-rot fungus (Pycnoporus sanguineus) and subterranean termite (Coptotermes curvignathus), weight loss (WL) due to SHS treatment, equilibrium moisture content (EMC) and moisture excluding efficiency (MEE), modulus of rupture (MOR) and modulus of elasticity (MOE) in static bending. The results were presented in this study and showed that SHS treatment improved the durability, hydrophobicity and dimensional stability of treated wood. Moreover, as an effects from SHS treatment, the colour of treated samples becomes darker compared to untreated due to chemical degradation. In contrary, the MOR and MOE were adversely affected by this treatment. The reduction of these properties were more severe on the increment of heating temperature. Between these two species, the strength of kedondong wood was affected severely by SHS treatment. The changes in chemical constituents were the primary reason for the changes in wood properties and the results were confirmed by the Fourier transform infrared analysis (FTIR). The results also revealed that the optimum heating parameters suggested by the RSM to obtain optimum improvement in the performance of the wood were 210 °C and 197 min, and 218 °C and 120 min for light red meranti and kedondong respectively.

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