2.3.2.2. Determination of cross-link density (m). The volume fraction
of rubber in swollen network of the vulcanizates Vr, was determined
by means of equilibrium swelling in acetone laboratory
grade at 25 C. The equilibrium swelling was used to calculate
the cross-link density, which is the number of network chain density
by applying the Flory–Rehner equation [12] as follow: