Binderless Panels Made with Black Spruce Bark

The bark of black spruce was thermo-mechanically refined and used to manufacture binderless bark-based fiberboard with various pressing temperatures, times, and panel structures in order to utilize an abundant bark resource for a better value-added application. The test results indicated that it is technically feasible to manufacture binderless fiberboard with refined black spruce bark through self-bonding under elevated temperatures over a reasonable period of pressing time. Binderless bark-based fiberboards with a homogeneous structure had very poor flexural properties due to the poor strength of bark itself; however, by using a sandwich structure with 30wt% wood fiber in the surface layers and 70wt% bark in the core layer it was possible to sufficiently improve panel flexural properties so that the manufactured binderless bark-based fiberboards was able to meet the mechanical property requirements of 115-grade fiberboard according to ANSI A208.2 (2009). Refining conditions had a great impact on the mechanical properties of binderless bark-based fiberboard.