BRILL TRANSITION OF POLYAMIDE 6.12

The crystallization of polyamide 6.12 was investigated by X-ray diffraction and infrared spectroscopy. Similar to polyamide 6.6, there exist a pseudohexagonal y modification and a triclinic a modification. The characteristic IR absorption bands of each modification were identified and assigned. In the amorphous state, polyamide 6.12 additionally shows an absorption band at 1255 cm-1. The γ modification can be obtained by heating an amorphous sample above the glass transition temperature near 40°C and is stable only at high temperatures. Cooling of the y modification immediately results in the Brill transition into the a modification. It could be shown that the Brill-transition temperature is identical with the annealing or crystallization temperature of the γ modification. The difference of the 100 and 010 lattice plane distances measured at room temperature as well as the ratio of the IR absorbances between some a and γ bands increase with increasing annealing temperature and can be used for the determination of the individual Brill-transition temperature of a sample. © 1990, Taylor & Francis Group, LLC. All rights reserved.