Preparation of NR sheets
Each NR sheet was prepared in a pan by adding coagulant into
diluted NR latex (2,000 mL filtered fresh NR latex 3000 mL
water). For formic and acetic acids, 300 mL 2% (v/v) were used.
In the case of wood vinegars, 300 mL 50% (v/v) was chosen for
preparing the NR sheets. The mixture of diluted latex and
coagulant was left for 2 h for complete coagulation. The
obtained slabs were compressed between two steel rolls and
then washed with water before drying at room temperature
with relative humidity of 50–60% for a week. The product
obtained from this process is called pre-drying NR sheet and
its further processed by drying at 50–60 _C for 2 days to be the
dry NR sheets. The NR sheets coagulated by using formic acid
and wood vinegar mixtures (3 mL formic acid 75 mL wood
vinegar 222 mL water for each pan) were also prepared for
antifungal efficiency comparison. The pH of all coagulant
aqueous solutions was in the range of 2.6–3.1.