Effects of boiling water treatment on the physical properties of Quercus variabilis virgin cork grown in Korea.

The effects of boiling water treatment on the physical properties of Quercus variabilis virgin cork (Qv VC) were examined and compared with those of Quercus suber reproduction cork (Qs RC). The water treatment was conducted at 100 °C for 1 h. Qv VC showed a significantly higher dimensional change in the three directions and lower weight loss than Qs RC by boiling water treatment. Untreated and boiled Qv VC showed higher density, air-dried moisture content, red/green (a*) and yellow/blue (b*) chromaticity, overall color change, shrinkage in all three directions, moisture adsorption on the entire surface, and swelling per 1% moisture content than untreated and boiled Qs RC. However, the lightness (L*) and water absorption on each surface were higher for Qs RC than for Qv VC. Moisture adsorption on each surface was comparable before and after heat treatment for both species. After boiling water treatment, the air-dried moisture content, dimensions, volume shrinkage, water absorption, and moisture adsorption on each surface and the entire surface increased, whereas L*, a*, b*, and swelling per 1% moisture content decreased. The results of the present study could be useful for further utilization of Qv cork growing in Korea.

Durability of heat-treated Paulownia tomentosa and Pinus koraiensis woods in palm oil and air against brown- and white-rot fungi.

This study aimed to evaluate and compare the effects of oil- and air-heat treatments on the durability of Paulownia tomentosa and Pinus koraiensis woods against Fomitopsis palustris and Trametes versicolor. The wood samples were treated in palm oil and air at 180, 200, and 220 °C for 2 h. The weight loss, morphology, crystalline properties, and chemical compounds of untreated and heat-treated wood after fungal attack were investigated. The significant difference in weight loss between oil- and air-heat-treated samples was shown at 220 °C. Heat-treated wood exposed to white-rot fungus showed a lower weight loss than that exposed to brown-rot fungus. The cell components in the untreated- and heat-treated Paulownia tomentosa and Pinus koraiensis at 180 °C were severely damaged due to fungal exposure compared to those at 220 °C. A fungal effect on the relative crystallinity was observed in heat-treated wood at 180 °C, whereas the effect was not observed at 220 °C. Following brown-rot fungus exposure, untreated- and heat-treated wood at 180 °C showed a notable change in the Fourier transform infrared (FTIR) peaks of polysaccharides, whereas no noticeable change in lignin peaks was observed. Heat-treated wood at 220 °C showed no noticeable change in the FTIR spectra owing to brown-rot fungus exposure. Exposure to white-rot fungus did not noticeably change the FTIR spectra of untreated and heat-treated wood.

Effect of densification on the physical and mechanical properties of the inner part of oil palm trunk impregnated with methylene diphenyl diisocyanate.

Oil palm (Elaeis guineensis Jacq.) plantations in Indonesia are increasing over the past few years. After economic productivity, however, the unproductive oil palm trunks are felled and mostly go to waste, especially the inner part of the oil palm trunk (IOPT). There are several modification methods to utilize IOPT, such as impregnation and densification. Methylene diphenyl diisocyanate (MDI) is a common resin used for impregnation in composite industries because it is non-toxic and has excellent physical and mechanical properties but it has never been applied for the impregnation of IOPT. This study aimed to analyze the effect of densification on the physical and mechanical properties of the inner part of oil palm trunk (IOPT) impregnated using methylene diphenyl diisocyanate (MDI) resin to obtain valuable information regarding the efficient utilization of unproductive oil palm trunks. IOPT was densified and compregnated with compression ratios (CRs) of 20% and 30%. The physical properties (density, moisture content (MC), and water absorption (WA)) and mechanical properties (modulus of elasticity (MOE), modulus of rupture (MOR), and hardness) of the compregnated samples were better than those of the densified samples. The density and mechanical properties at CR 30% were higher than those at CR 20%. The improvements in density, MC, and WA of the compregnated IOPT with CR 30% were 127%, 54%, and 70%, respectively, compared to that in untreated IOPT. Furthermore, improvements in the MOE, MOR, and hardness of the compregnated IOPT with CR 30% were 489%, 379%, and 393%, respectively. The mechanical properties of the compregnated IOPT at CR 20% and 30% increased two- to three-fold from strength class V in control IOPT to strength class III in compregnated IOPT with CR 20% and to strength class II in compregnated IOPT with CR 30%, respectively.