Profiles in Dimensional Behavior of Particles in Simulated Particleboard Constructions

Dimensional changes in simulated particleboard constructions of aspen were studied to determine behavior patterns of particles when subjected to compression, soaking, and subsequent reconditioning. While this study was designed to gain some idea of strain, behavior throughout the profile of a simulated particleboard construction, some projection can be made into particleboard practice. In the thickness direction of particleboard, particles near the surfaces may be compressed to a greater degree than the inner particles as a result of pressing. Greater swelling as a result of soaking, greater compression retained after swelling, and greater shrinkage would then also occur in the outer particles. In the width direction of particleboard, particles may increase in dimension as a result of pressing. The dimensional increases would be greater in the inner particles and would increase with degree of imposed compression. Swelling, as a result of soaking, would be greatest in the outer particles. The degree of swelling as a result of soaking, in both thickness and width of particles in the outer surfaces of this study, was greater than normal swelling for aspen. Extreme swelling forces could, therefore, be present between particles in the outer strata of particleboard when exposed to high moisture content conditions. In making the above statements relative to particle behavior in particleboard, it is also noted that temperature during pressing will vary throughout the board because of the uneven volumetric distribution and subsequent compaction of particles during the board formation process. Thus, in any given strata of a board, a combination of temperatures, moisture contents, and degrees of compression will be present. As a result of this, adhesion and recovery effects will also vary throughout a particleboard.

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