CALORIMETRIC AND X-RAY-INVESTIGATIONS OF POLYAMIDE-6 AND ITS BLENDS WITH A POLYETHYL ACRYLATE ELASTOMER .1. PHASE-TRANSITION BEHAVIOR OF POLYAMIDE-6

The influence of thermal and mechanical pretreatment on the phase tran sition behaviour of Polyamide-6 (PA 6) has been investigated by means of differential calorimetry and wide angle X-ray scattering (WAXS). Th e crystallization of PA 6 during slow cooling or quenching is facilita ted when shear forces have acted on the melt before, DSC heating curve s of samples which have been oriented by precipitating from a formic a cid solution or by shear forces acting on the melt prior to crystalliz ation show three endotherms (T-mTm1Tm2). By means of dynamic WAXS inv estigations (HASYLAB, DESY) it could be shown for the first time that under certain conditions the Brill transition takes place in PA 6 crys tallites and that it happens continuously during heating and cooling, DSC curves do not indicate the Brill transition, Synchroton radiation experiments show that under the chosen experimental conditions it is a ''reversible'' process.