Properties Of Pine Wood Research Articles

Improvement of white pinewood properties by impregnation with thiourea-formaldehyde resin and orthophosphoric acid

White pinewood was impregnated with thiourea–formaldehyde (TUF) resin and orthophosphoric acid (OPA) as a crosslinking agent. The best weight gains (55–138%) were obtained after impregnation with an aqueous solution of TUF resin for 1 h and impregnation with aqueous solutions of OPA at different concentrations for 1 h. Water uptake of treated wood was found to be 23% after a water-soaking test of 168 h, and a maximum antiswell efficiency was found to be 18% for a 85% OPA solution. Compression strength of the treated wood also improved with the highest value 62 KN/m2 for wood treated with a 70% OPA solution versus a value of 40 KN/m2 for untreated samples. Fire retardancy of the treated wood samples was also improved based on concentration of OPA. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 390–397, 2000

Quantitative characterization of the subsurface acid–base properties of wood by XPS and Fowkes theory

The subsurface acid–base properties of pine wood have been quantitatively characterized in terms of the C1s peak displayed by the X-ray photoelectron spectroscopy (XPS) and the Fowkes acid–base theory. Using the ratio of acidity to basicity, A/B, to characterize the pine wood, it is found that the pine wood is strongly basic and weakly acidic as expected from previous wetting experiments. It is found, however, that the wetting method gives an acid/base ratio which is lower than that determined by XPS. The difference is suggested to be due to the probing depth. The wetting result corresponds to the outermost surface of wood while the XPS value reflects the subsurface of wood. The surface is known to be more easily oxidized than the subsurface. Furthermore, based on a comparison in which the acid/base ratio is plotted as a function of the oxygen/carbon ratio for pine wood and some hardwoods reported in the literature, the softwood seems to have a lower A/B ratio than the hardwood. The reason is that the softwood has a stronger basicity and a weaker acidity than the hardwood.

Creep of wood under a large span of loads in constant and varying environments

Extensive bending creep experiments were made to measure the viscoelastic and mechano-sorptive properties of pine wood. It is observed that under constant, similar to ordinary indoor environment, creep is linearly related to the loads when the loads are below 30% of the ultimate strength, and the relation becomes nonlinear when the loads are higher. Wood of small elastic modulus creeps more than that of large elastic modulus under the same load. The mechano-sorptive effect is stronger for heavily loaded wood than that for lightly loaded. It is stronger for wood with lower elastic modulus and vice versa. The mechano-sorptive effect is negligibly small at low moisture content and it gets very large at high moisture content (...)