Comparison of the Properties of Heat and Radiation Cured Wood-Polymer Combinations

Comparisons were made between certain physical and mechanical properties of Betula lutea Michx. f. polymerized with methyl methacrylate “in-situ” by gamma irradiation and by heat. Betula lutea was used because of its freedom from tyloses, low extractives, and high permeability. No significant differences were found between the two polymerization systems when tested for compression perpendicular, shear, permeability, diffusion coefficient, and antishrink efficiency. The surface hardness of the radiation-polymerized material was about 25 percent greater than for the heat- polymerized combination, possibly due to the preferential evaporation of monomer near the surface. The permeability of treated and untreated wood samples was apparently increased when the cobalt-60 radiation exposure was increased from 3 to 10 megarads. There was no apparent mechanical degradation up to 10 megarads of exposure. Linear regression equations were established relating compressive stress, hardness, and diffusion coefficient to density and diffusion coefficient to permeability over a limited range of values.

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