Methods of calculation of the critical conversion in the formation of network polymers

Mathematical methods of calculation of the critical conversion (gel point) in the formation of cross-linked polymers by polycondensation, cross-linking of macromolecules and three-dimensional polymerisation are considered. The results obtained using the statistical approach ('ideal' polycondensation), the concept of bond blocks (the 'non-ideal' or 'non-statistical' polycondensation) and kinetic calculations that allowed the determination of the gel point in three-dimensional polymerisation processes are discussed.