Hardboards from mixtures of Philippine hardwoods after chip storage

Less than 10% weight loss occurred after 9 months of storage under conditions that resulted in over a 20% loss with aspen chips. High-density hardboards made from aged Philippine hardwood chips had better bending strength, internal bond, and thickness swelling than boards made with fresh chips. The tensile strength and linear movement were not as good. Fifty species of Philippine hardwoods were used for chip storage and hardboard experiments. Chips were stored for 9 months in an insulated polystyrene foam box with air inlets and outlets and fed with water saturated air. Chips were converted into hardboard quality pulp using a small batch-type pressurized refiner. Dry-formed, 1/8-inch, high-density hardboards were made from the pulps after air drying. Chip weight loss after aging was calculated from the ovendry weight of the chips before and after aging. The hardboards were evaluated by the same procedure specified in A.I.D. Report No. 5, "Hardboards From Mixtures of Philippine Hardwoods." Biological activity was apparently greater in the aspen than in the tropical hardwood mixture. The aspen chips reached a maximum temperature of 113 degrees F. and had a 22.4% weight loss compared to 92 degrees F. and 9.4% weight loss for the tropical hardwood chip mixture. Hardboards made with pulps prepared from fresh and aged chips from the tropical hardwood mixture and domestic hardwood easily met the requirements of Voluntary Product Standard PS 58-73 for standard hardboard for those properties measured.