Analysis of ASTM D 1037 accelerated-aging test

The ASTM D 1037 six-cycle accelerated-aging test for wood-based panel products was analyzed to determine how each successive aging cycle and selected steps in each cycle contribute to panel deterioration. Hardboard, particleboard, flakeboard, waferboard, and oriented strandboard were evaluated. The rate of panel deterioration generally decreased with each successive aging cycle. Four cycles of accelerated aging had essentially the same effect on panel bending strength and stiffness as the standard six cycles. Deletion of the 20-hour freezing step from the aging cycle had practically no effect on the outcome of the exposure. Deletion of the steaming steps, however, resulted in less panel deterioration. Deletion of both freezing and steaming steps produced about the same amount of panel deterioration as deletion of the steaming steps alone. In some cases, interpretation of results depended on whether bending strength and stiffness calculations were based on initial specimen thickness or thickness after aging. Findings from this study indicate definite opportunities for developing an abbreviated alternative to the current time-consuming accelerated-aging test. We propose an alternative exposure, which will be investigated in a future study. The current U.S. test for evaluating bond durability of phenolic-bonded particleboard and other wood-baaed panels subjected to severe exposures is the six-cycle accelerated-aging test in ASTM D 1037 (3). The National Bureau of Standards (NBS) developed this test in the 1930s to determine fiberboard sheathing durability (16). The various exposures used were baaed on NBS experience with aging of paper; wetting and freezing steps were added because fiberboard sheathing maybe subjected to this type of exposure. No attempts were made to determine how much each exposure step contributed to fiberboard deterioration. The most often reported problem with the ASTM D 1037 test is that it is much too long to be used as an inplant quality control check. Each of the six cycles contains six individual exposure steps. The test normally takes 2-1/2 weeks to complete since the cycle can be interrupted only at the freezing step. After accelerated aging, additional time is needed to recondition the specimens before stiffness and strength can be measured. The two objectives of our study were to 1) evaluate the progressive deterioration of products with each successive exposure cycle in the ASTM D 1037 test; and 2) determine how various steps in the ASTM D 1037 six-cycle test contribute to panel deterioration. Results of this study were used to develop a less time-consuming acceleratedaging test, which will be evaluated in a future study.