Temperature’s effect on color change and mechanical properties of poplar powder compact formed by warm compaction

Abstract

Warm compaction technology is an eco-friendly method to improve the added value of poplar. In this work, the wood powder was compacted in the mold between 120 °C to 200 °C, at 80 MPa for 30 min. The color change, chemical properties, and mechanical properties were evaluated. The color of the formed compaction darkened uniformly. The CIE lightness color coordinate (L*) and chroma coordinates a* and b* decreased with the increase of forming temperature. Fourier infrared spectral analysis showed degradation of carbohydrates, along with the formation of a new chemical structure of darker color. Mechanical properties including modulus of rupture (MOR) and modulus of elasticity (MOE) of compacted wood increased initially and then decreased. These results provide a reference for the surface color control of thermally forming materials.