To maximize value recovery from post mountain pine beetle - wood (MPB wood) for the manufacture of wood composite products, it is desirable to use completely MPB wood as OSB, MDF or particleboard furnish. The objective of this study in the first fiscal year was to determine and quantify the chemical properties, bondability and wettability of grey stage MPB wood in order to minimize or reduce the impact of beetle-killed wood on composite panel manufacturing. Investigation of the chemical and physical properties of grey stage MPB wood, such as wood pH and buffer capacity, wettability and bondability was conducted. Green lodgepole pine and aspen were used to compare the test results. Various wood furnish derived from MPB wood and green lodgepole pine have been prepared for the manufacturing testing of OSB, MDF and particleboard panels in the next fiscal year. The test results indicated that some basic chemical and physical properties of lodgepole pine, particularly in the sapwood area, had undergone changes associated with MPB infestation.
Based on the test results so far, the following conclusions are made:
1. The pH values of both the MPB heartwood and sapwood were lower and their acid and base buffer capacities were higher than those of the green lodgepole pine. As a result, the curing rate of pH sensitive adhesives such as UF and MUF may be affected.
2. MPB sapwood showed extremely fast and high water absorption but its thickness swell was lower than those of the MPB heartwood, green pine sapwood and heartwood regardless of water temperatures.
3. Thickness swell of the MPB sapwood almost reached to the maximum in the first two hours of water soaking at 20°C.
4. The water absorption of sapwood was higher but the thickness swell was lower than that of heartwood in both MPB wood and green lodgepole pine. The rates of water absorption and thickness swell of these woods were fast in the first several hours and slowed down thereafter.
5. Both the MPB heartwood and the green pine heartwood behaved very similarly in terms of water absorption rate and percentages. It appeared that the beetle infestation did not significantly affect the water absorption property of the MPB heartwood.
6. Edge thickness swell and center thickness swell of the MPB sapwood behaved very similarly in terms of the rates and percentages, which were quite different from those of the other woods and suggest that the blue stained MPB sapwood had probably undergone profound changes.
7. Higher temperatures led to faster and more water absorption. The water temperature affected the MPB sapwood more than the MPB heartwood.
8. Thickness swell reached to the equilibrium faster at higher temperatures.
9. Water pH had little influence on water absorption but affected thickness swell. The thickness swell of both MPB wood and lodgepole pine decreased under both acidic and alkaline conditions.
10. The bonding strength of MPB and green lodgepole pine with liquid PF, powdered PF and liquid UF were generally comparable to that of aspen at high press temperatures. Both the MPB wood and green pine showed lower bonding strength than aspen at low press temperatures. This may have significant implications on the bonding quality of the core layer of panels.
11. At high temperature (200°C), green pine produced substantially higher MDI bonding strength while MPB wood and aspen gave lower and similar bonding strength. This was also the case at low press temperature (140ºC), particularly in longer press time. The MDI bonding strength of MPB wood was close to that of aspen under all these press time and temperature conditions. However, aspen appeared to be less sensitive to low press temperature in terms of bonding with MDI. Therefore, green lodgepole pine may be more suitable as a core furnish material than the MPB wood in the manufacture of OSB, where MDI resin is widely used as a core layer adhesive. Grey stage MPB wood may be more suitable as an OSB face furnish material. This hypothesis will be carefully tested in the 2nd fiscal year of this project.
Insect killed wood - Utilization
Insect-killed wood - Recovery
Pinus contorta Dougl. var. latifolia - North America