Disordering of crystalline PEEK upon mechanical treatment

It has been established that crystalline PEEK can become completely amorphous upon rolling at room temperature. This effect was verified by data of differential scanning calorimetry, X-ray diffraction and density measurements. In contrast to quenched amorphous PEEK samples, cold crystallization in rolled amorphous samples is shifted to lower temperatures and starts just with the onset of the glass transition. This shift. along with the decrease in the heat of cold crystallization from 21 J/g (for quenched amorphous sample) to 11 J/g, suggest some retention of paracrystalline structure in rolled amorphous samples.