2.3.2. Physico-chemical measurements
2.3.2.1. Soluble fraction. Measurements of soluble fraction were carried
out as follow, the cured samples, about 0.2 g were accurately
weighed (Wo) and placed in a special stainless grids. The grids containing
samples are transferred to special round flask 2/3 filled
with acetone. The heating was carried out under reflux for 24 h.
After extraction, the samples were dried to constant weight (W1)
in dry oven at 50 C. The soluble fraction was calculated as follow:
Soluble fraction ¼ Wo W1=Wo