The Effect of Species and Substrate Density on the Flexural Properties of Epoxy-Impregnated Barkboard
Keywords:Barkboard, impregnation, epoxy, wood-polymer composites
AbstractBark from red oak, yellow-poplar, soft maple, and beech was individually mixed with 6% (by weight) powdered phenolic resin and pressed into boards having nominal densities of 40, 50, 60, and 70 lb/ft3 (0.64, 0.80, 0.96, and 1.12 g/cm3). Half of these boards were used as controls and half were impregnated with a solution of 100 parts by weight of epoxy resin, 25 parts styrene oxide, and 12.06 parts N,N-diethyl-1, 3-propanediamine. Polymer retention was found to be linearly related to the substrate density and was somewhat dependent upon the species of bark. The impregnation process resulted in dramatic changes in the flexural properties of the barkboard. Increases in MOR of 3.0- to 4.0-fold and in MOE of 2.6- and 3.6-fold were observed over control values, with the largest improvements occurring in the red oak specimens. In contrast to the control specimens, MOR and MOE values for the epoxy-impregnated specimens were not well correlated. In addition, correlations of MOR with the substrate density and polymer mass loading were generally low or varied greatly with bark species. MOE correlations were notably higher, but variable.
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