Study on Collapse-shrinkage Characteristics in Plantation-grownEucalyptus Wood Under Continuous and Intermittent drying regimes

摘要

Collapse-type shrinkage is the greatest obstacle to prevent planted eucalypts from beingused for solid wood products. In order to make the suitable drying schedules for high effectiveutilization of eucalypt wood, the total shrinkage and collapse on two species of difficult-to-dry E.urophylla and E.grandis wood under continuous and intermittent drying regimes were measured. Theresults show that total shrinkage and collapse in both eucalypts exhibited higher values forcontinuous drying than intermittent drying. With increasing drying temperature, total shrinkage andcollapse increase in both drying regimes, while the increasing magnitude of both parameters becomesapparently larger for continuous drying than intermittent drying regime, in particular highertemperature condition. Properly elevating drying temperature to make up for the intermittent-waitingtime may be allowed for intermittent drying regime. Drying duration at each intermittent dryingperiod has a greater effect on total shrinkage and collapse of eucalypt wood. When more than a dryingduration of 6 hours at an intermittent drying period is used, the differences in shrinkage and collapsebetween both drying regimes are very slight. Intermittent duration at an intermittent drying period hasa comparatively larger effect on total shrinkage and collapse. Accordingly, we may draw a conclusionthat intermittent drying regime is very likely to be a potential drying one suitable for collapse-pronelower-density plantation-grown eucalypt wood.