Properties of Particle- and Hardboard Made from Healthy and Beetle-Killed Southern Pine

The southern pine beetle kills pine trees on millions of acres in the southeastern United States each year. In this study we investigated the suitability of wood from beetle-killed trees as a furnish for particleboard and hardboard. Particleboard prepared from trees dead for 3 months (Class A) and 30 months (Class B) in western North Carolina had moduli of rupture and elasticity, internal bond, screw withdrawal, hardness, water absorption, thickness swelling, and linear expansion properties similar to those of boards manufactured from healthy trees. Boards produced from beetle-killed pines met industry specifications for all properties except two furnish mixtures, 100 percent B and 75 percent H/25 percent A, which had excessive linear expansion. Particleboards from beetle-killed trees were much darker than those from healthy trees. Quality of hardboard from beetle-killed trees was also generally similar to that from healthy trees. Boards easily met industry specifications for all properties except linear expansion. Boards prepared from 100 percent Class A or. Class B trees narrowly failed this specification, but when 50 percent of the furnish was from healthy trees, the boards met specification. The yield of wood fiber from beetle-killed trees was slightly lower than from healthy trees and the percent of fines slightly higher. Moisture content of beetle-killed trees was considerably lower than that of healthy trees. These results indicate that wood from beetle-killed trees can be used satisfactorily as furnish for both particleboard and hardboard if mixed with wood from healthy trees to minimize effects on board characteristics and production schedules.

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