Dear student

The reaction involved in preparation of nylon- 66 is called polycondensation reaction. Nylon - 66 is synthesized by polycondensation of hexamethylenediamine and adipic acid. The reaction is as follows-

C4H8-2(COOH) + C6H12-2(NH2) ---->(C12H22N2O2)n. You can see the structural representation in the 11th class chemistry ncert book, vol-2. Hope that helps.

All the best