Structural transitions during the cold drawing of aliphatic ketone terpolymers

Cold drawing of aliphatic ketone terpolymers with CH3 substituents is shown to promote production of the high density α crystal phase. The quantity of the minor α component decreases with increasing CH3 content and the solid–solid α→β phase transition temperature is shown to be lower compared with the unsubstituted polymer. Draw rate affects the amount of α phase produced: low draw rate favours α phase. This is explained in terms of strain-induced heating effects: high rates increase the temperature above the Tα→β transition.