2. Experimental
2.1. Materials
The plywood and decorative veneer used for fabricating the
test samples were supplied by Easywood Co., Ltd., South Korea.
The decorative veneers were 0.5-mm-thick maple, while 7-mm-thick plywoods manufactured in China were used. Their moisture
contents were 0.08% and 3.5%, respectively. Polycardanol, which
was prepared by enzyme-catalyzed oxidative polymerization, was
kindly supplied by Hyundae Paint Co., Ltd., Korea.Fig. 1depicts
the chemical structure of the polycardanol used in this work.
The as-received polycardanol was comprised of pre-polymer and
thermally curable. Its monomer-to-polymer conversion was 97.7%.
Sodium hydroxide pellets and glacial acetic acid were supplied as
general laboratory reagents. Acetic anhydride with a density of
1.08g/cm
3
andboiling temperatureof 140
◦
Cwasused. Aformalde-hyde solution of 40% weight of solid per unit volume of liquid and
hexamine as a hardener were added to make the CF resin. The CF
resinwaspolymerizedbyadding1ml of sodiumhydroxidesolution
to the resin mixture. In the second stage of the experiment, 1ml of
15% hexamine was also added[10]. Blends of various CF/polyvinyl
acetate (PVAc) compositions were prepared. To make the CF/PVAc
hybrid resin, 5, 10, 20 or 30wt % of PVAc was added to CF and the
mixture was stirred for 20min