Effect Of Thermal Modification Research Articles

Termite Resistance of Thermally-Modified Dendrocalamus asper (Schultes f.) Backer ex Heyne.

The effects of thermal modification on the resistance of Dendrocalamus asper against Microcerotermes losbañosensis were investigated after exposure to virgin coconut oil at 140–200 °C for 30–120 min. The results showed that heat treatment significantly improved bamboo’s resistance to termites based on mass losses and visual observations. The enhancement was highest at 200 °C. Prolonged treatment had a positive effect on the resistance at lower temperatures only.

Effect of thermal modification on mechanical properties of Canadian white birch (Betula papyrifera)

Wood is a renewable material widely used in the construction industry. However, it is susceptible to fungal degradation. Several chemical products have been developed to improve its durability, but the toxicity of some of these products limits their use. One alternative to chemical treatment is thermal modification of wood. This method improves the dimensional stability of wood and reduces its susceptibility to decay. The impact of different parameters (maximum temperature, heating rate, holding time and gas moisture content) of thermal modification on the mechanical properties of Betula papyrifera was studied in a prototype furnace. The results show a marked decrease in the modulus of rupture with increasing temperature while the modulus of elasticity does not seem to be affected. The hardness increases with maximum modification temperature, and in the absence of moisture in gas, and there is an improvement in the dimensional stability after thermal modification.

Effect of thermal modification on the properties of narrow-leaved ash and chestnut

The concept of thermal modification has evolved from a challenging research program to commercial reality in several European countries in recent years. The aim of this study is to determine the change of various physical properties (oven-dry density, air-dry density, weight loss, swelling and anti-swelling efficiency (ASE)), compression strength parallel to grain, colour difference (Δ E), glossiness and surface roughness of narrow-leaved ash ( Fraxinus angustifolia Vahl.) and chestnut ( Castanea sativa Mill.) woods after heat treatment under different temperatures and durations. For this study two different temperatures (160 °C and 180 °C) and two different durations (2 h and 4 h) were considered. A stylus method was employed to evaluate the surface characteristics of the samples. Roughness measurements by the stylus method were made in the direction perpendicular to the fiber. Four main roughness parameters which are mean arithmetic deviation of profile ( R a), mean peak-to-valley height ( R z), root mean square roughness ( R q), and maximum roughness ( R y) obtained from the surface of wood were used to evaluate the effect of heat treatment on the surface characteristics of the specimens. The properties studied were significantly different ( p = 0.05) at two temperatures and two durations of heat treatment. Based on the findings of this study, the results showed that oven-dry density, air-dry density, swelling, compression strength parallel to grain and surface roughness decreases with increasing heat treatment temperature and time.

Wettability of sapwood and heartwood of thermally modified Norway spruce and Scots pine

In this research, the effect of thermal modifications at 170°C, 190°C, 210°C and 230°C on the wettability of sapwood and heartwood of Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) was studied by measuring the static contact angles of distilled water on the surfaces as a function of time. The results were compared to industrially kiln-dried reference samples. The thermal modification at the lower temperatures of 170°C and 190°C increased the wettability of all wood materials with the exception of the heartwood of pine that had been thermally modified at 170°C, which was the most water-repellent material in the whole study. Thermal modification at the very high temperature of 230°C was needed to decrease the wettability of wood. The differences in water repellency between sapwood and heartwood were greater for pine than for spruce.

Effects of thermal modification on the adhesion between spruce wood (Picea abies Karst.) and a thermoplastic polymer

In order to study the effect of thermal treatment on the adhesion between wood and a nonpolar thermoplastic polymer, spruce wood boards (Picea abies Karst.) were heat-treated and bonded with polyethylene. As a result the contact angle of an applied water droplet increased significantly. A strong improvement of the adhesion between the modified wood surface and polyethylene was found by mechanical tests on unmodified and thermally modified samples.

The effects of thermal modification on crystalline structure of cellulose in soft and hardwood

In this study the crystallinity and estimations of relative triclinic ( I α ) and monoclinic ( I β ) structure content of cellulose isolated from heated spruce ( Picea orientalis) and beech ( Fagus orientalis) wood samples were determined by using Fourier Transform Infrared (FT-IR) spectrometry. Heat treatment was applied on the test samples in an oven at three different temperatures (150, 180 and 200 °C) and two different durations (6 and 10 h) under atmospheric pressure. It was determined that crystallinity of cellulose in wood samples increased with thermal modification. The results indicate that the changes in crystallinity of cellulose in wood samples related to not only temperature but also time during thermal modification. I α / I β ratio of cellulose in spruce and beech wood samples changed with thermal modification, but it was established that monoclinic structure was dominant in cellulose crystalline structure. It was designated that the crystalline structure of cellulose in spruce wood samples affected from thermal modification more than in beech wood samples.

Effects of thermal modification on the structural properties of thermotropic liquid crystalline copolyester and phenoxy resin blends

AbstractThe effects of thermal modification on the structural properties were studied for a poly(ethylene terephthalate‐co‐p‐hydroxybenzoic acid) liquid crystal bended with phenoxy resin. Poor miscibility and phase separation between the blend components are observed by the temperature dependence of dynamic mechanical properties of sample molded at 260°C, over the composition range studied. The miscibility of the blends is increased by molding at 280°C, and the blends molded by increasing the processing time show a dynamic mechanical transition to a homogeneous blend. These changes are the result of an interchange reaction between the blend components. A rubbery modulus has been observed for such blends. This implies the formation of cross‐linked structures that accompany the interchange reactions.