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Thermal treatment of Nigerian-grown Albizzia zygia and Funtumia elastica wood in soy oil medium.
2008 - IRG/WP 08-40413
Thermal treatment in soy oil medium is one of the techniques used as a substitute to the chemical treatment in wood preservation. However, the effects of this technique vary from one species to another and hence the need to investigate the response of individual species to it. Thermal treatment of air-dried Nigerian-grown Albizzia zygia and Funtumia elastica wood was carried out in a vessel containing soy oil at a temperature of 220°C for 2hours. This was followed by the determination of hygroscopy and swelling by water soaking method; surface energy by the sessile drop contact angle method; pH and buffer capacity by the cold extraction method. The process of soy-oil thermal treatment resulted in significant reductions in hygroscopy, swelling properties and pH in both species with accompanying increase in buffer acid and alkaline buffer capacity. The surface energy which is an indication of wettability was reduced in Albizzia zygia but increased in Funtumia elastica. The reductions in hygroscopy and pH are indications of cellulose degradation during the heat treatment process leading to build up of acid formation. The reduction in hygroscopic behaviour indicates potential for stability in wood-water relationship especially when the material will be used in a continuously-changing ambient environment. The reduction in surface energy in Albizzia zygia implies that soy-oil-thermally modified wood from this species will have reduced interfacial attractions with most chemical adhesives. On the other hand, the increase in surface energy in Funtumia elastica shows possibility of improvement in the level of interfacial attractions between wood (substrates) and adhesives. The reduction in pH in both species is expected to have a two-way effect; a benefit through reduction in adhesive curing time and an adverse effect through expected reduction in strength properties.
L Awoyemi


Laboratory and field exposures of FRT plywood: Part 1. Physical test data
2008 - IRG/WP 08-40426
Our understanding of the laboratory induced degradation with fire retardant systems is currently limited since we are unable to correlate laboratory steady-state experiments with actual in-service field degradation. Current model studies have generally been limited to isothermal rate studies with selected model FR chemicals. Other factors also play a major role in the degradation of FR-treated wood. These factors, which have not been studied in any detail, include relative humidity/moisture content cycles and thermally-induced evolution of ammonia from ammonium phosphates to give phosphoric acid. The objective of this study was to determine the relationship between laboratory and field results based on strength-temperature-relative humidity (moisture content)-FR chemical interactions. The impact of the variables was evaluated by measuring bending strength properties and comparing matched laboratory and field exposure samples. In this first paper, the physical test data show the positive effects of adding a buffering system to model FR compounds when exposed to high moisture environments and the negative effects of increasing the moisture in the in-service environment during exposure.
H M Barnes, J E Winandy, C R McIntyre


Studies on Effect of pH on Copper Availability in Copper-Based Preservatives
2010 - IRG/WP 10-30549
Laboratory methods have been employed to investigate the pH effect on the copper solubility of basic copper carbonate. The pH was controlled using two different approaches. One was with the adjustment of pH of the solutions by acid or base using sulfuric acid or sodium hydroxide until the solution equilibriums were obtained for each defined pH. A second approach was to control pH with buffer solutions to provide the designated pH range. Differences in copper solubility at the same pH with these two approaches were observed. The results generated from this study are compared with previously presented data and are discussed in terms of the influence of methodology, potential interactions of component(s) and the effect of the pH control agents.
L Jin, P Walcheski, A F Preston


Mechanical Properties of Hydrothermally Treated Beech Wood in Buffered Mediums
2012 - IRG/WP 12-40597
Hydrothermal treatment of beech wood in buffered mediums was carried out by aim of controlling the destructive effect of acids formed by degradation of carbohydrates on strength properties. Different mediums (water, buffer5, 7 and 8) and temperatures (160 and 180 °C) were used. Mechanical properties of specimens including modulus of rupture (MOR), modulus of elasticity (MOE) and toughness were determined. Hydrothermal treatment in buffer 5 caused a considerable loss in MOR, while treatment in buffer 8 slightly decreased the MOR. MOR losses in both temperatures were observed in buffer 5> water> buffer 7> buffer 8, respectively. MOE of all specimens showed slight increase except those treated in buffer 5. Toughness losses were obtained in buffer 5> water> buffer 7> buffer 8, respectively. Buffering the medium of hydrothermal treatment in neutral level prevents the strength loss and extends the usage of heat-treated wood in load-bearing applications.
A Talaei A Karimi, K Yaghoobi, A Talaei


Chemical Analysis of Hydrothermally Treated Beech Wood in Buffered Mediums
2012 - IRG/WP 12-40604
Hydrothermal treatment of beech wood in buffered mediums was carried out to study the effect of different mediums of heat treatment on crystallinity index of treated specimens due to degradation of carbohydrates. Different mediums (water, buffer5, 7 and 8) and temperatures (160 and 180 °C) were used. ATR spectra focusing on indexes of carbohydrates degradation obtained and analyzed. Results showed that crystallinity index of cellulose in specimens treated in water and buffer 5 were increased in both temperatures; whereas it didn’t changed in specimens treated in buffer 7, 8 in 160°C but increased slightly in 180°C. The ratio (T1740/1506) was decreased in treated specimens in water and buffer 5, whereas it did not change in treated specimens in buffer 7, 8 in 160°C and slightly decreased in 180°C. The intensity of carbonyl peak (1740 cm-1) was higher in specimens treated in buffer 5, water, and buffer 7, 8, respectively. It seems that because of higher amount of acids released in higher temperature (180°C), the ability of buffers to buffer the medium decreased. Thus, deacetylation and degradation of carbohydrates increased, consequently. Buffering the medium of hydrothermal treatment in neutral level prevents the strength loss and extends the usage of heat-treated wood in load-bearing applications.
A Talaei, A Karimi