where c p is the crosslink density (mol/m3), Vs is the molar volume of toluene (1.069x10-4 m3
/mol) at 25 ƕC, o Vr is the fraction of rubber in the swollen gel and F is the interaction parameter (0.39 for NR). It was found that the crosslink density, gel and soluble fractions of NR were 0.82 mol/m3, 20.92 % and 79.08 %, respectively.