Wood fiber production from downed timber for manufacturing wood polymer composite: fiber property characterization

Massive amount of downed timber is generated by hurricanes and tornados. This research studied the properties of wood fibers (WFs) generated from downed loblolly pine (Pinus taeda L.) trees at different maturity (ages 15, 30, and 39 years) with various natural environmental exposure periods (0, 6, and 12 months) for wood polymer composite (WPC) manufacturing. The wood fiber critical properties for WPC manufacturing, including particle size and morphologies, physical and chemical properties, and thermal stability, were characterized. Prolonged environmental exposure increased WF surface roughness. The density and 1% sodium hydroxide solubility of WFs for the 15 – and 30-year-old tree decreased after 12 months of environmental exposure. The WFs generated from the 39-year-old tree contain extractives due to heartwood development, resulting in significantly less moisture absorption. Thermogravimetric analysis results showed no significant change in the thermal stability of WFs generated from the 15 – and 30-year-old trees after natural environmental exposure because of the loss of degraded wood components. The cellulose and lignin thermal degradation peak temperatures decreased by up to 9 and 6 °C for WFs extracted from the 39-year-old tree. The degraded wood components were fixed within WFs due to extractives, causing thermal degradation peak temperatures to decrease.