The RH was obtained from rice mill in Chuncheon, capital city of
Gangwon Province, South Korea. The moisture content of the RH
particles prior to the manufacture of the sandwich-structured
composite was 3–5% based on the oven-dry weight of the RH particles.
The average length, width, and thickness of the RH particles
used in the experiments were 6.79 ± 0.35 mm, 2.96 ± 0.26 mm,
0.17 ± 0.02 mm, respectively (these values were an average of 30
the RHs and standard deviation). European ash (Fraxinus excelsior)
wood strands, (the strand size: length 90–100 mm, width:15–20 mm, and thickness: 0.8 mm) were obtained from a commercial
veneer company in Incheon, South Korea. A commercial liquid
PF resin (phenol/formaldehyde/catalyst ratio: 28.2/44.0/27.8) with
a solid content of 39.5% (viscosity: 92 cp, specific gravity: 1.159
and pH: 11.9) was used as an binder in the manufacture of the
particleboards.