Thermal linear expansion of selected Philippine woods and its correlation with relative density

• Main Author: Rosillo, Jimmy R.
• Format: text
• Language: English
• Published: Animo Repository 1986
• Subjects: Wood > Thermal properties; Specific gravity; Physics
• Online Access: https://animorepository.dlsu.edu.ph/etd_doctoral/614
• Institution: De La Salle University

The study determines the thermal expansivity of nine selected species of wood and their correlation with relative density. It also aims to determine the effect of varying amounts of electric current as source of heat energy on the expansivity of wood. Ninety samples coming from the 9 selected species of wood were exposed to two levels of electric current. One-half of the 10 samples from each species were exposed to 1.0 A and the other half to 1.2 A current. The coefficient of linear expansion for each sample was computed and was tabulated. The relative densities of the nine species of wood were determined by the loss of weight and density method based on ovendry weight and volume. The moisture content removed during the test and when ovendried was also determined from each sample. The data were analyzed by the use of t-test, two factor analysis of variance and correlation analysis. Result of the analysis of variance for the two levels of electric current (Factor A), species of wood (Factor B), and ranges of temperature (Factor C) showed a significant difference in the expansion of wood between levels of current, between species of wood and between ranges of temperature. The number of significantly different pairs of species decreases as the range of temperature is increased. The expansivity of wood is greater at 30-40 Centigrade degrees than at other ranges of temperature. Wood generally expands until a temperature range of 60-70 Centigrade degrees.The coefficient of linear expansion and the relative density of the 9 species of wood are moderately and inversely correlated at the 30-40 Centigrade degrees range of temperature with a correlation coefficient of -0.583. A t-test of significance of the value of r at 5 percent level showed no significant difference. Based from the results, it can be concluded that coefficient of linear expansion of wood is dependent on the amount of current used and expansion of wood decreases as the temperature is increased above 40 Centigrade degrees. Expansivity of wood is not correlated with its relative density.