AbstractThe thermally induced solid‐state polymerization of 66 nylon was investigated. It was found that the rate‐controlling step in the process is chemical reaction. A mechanism of the form, rate =ktnwas shown to hold. The reaction rate constant was found to bek= 1.53 × 1010exp [ − 12,960/RT]. Units ofkare (hours)−0.51. Activation energy determined in this work compared closely to that determined for nylon 6 solid‐state poly