INFLUENCE OF AGING ON THE CRYSTALLIZATION PHENOMENON OF ISOTACTIC POLYSTYRENE

The crystallization from the glassy state of different samples of isot actic polystyrene (iPS) was investigated with different techniques, su ch as differential scanning calorimetry, infrared analysis, and polari zed optical microscopy. The different samples of iPS were obtained by aging the glassy iPS films at room temperature and at 70 degrees C; th e behavior of the aged films was compared with that of a fresh sample, brought to the crystallization temperature as soon as prepared. The t emperature of crystallization was 140 degrees C. All the techniques in vestigated to follow the crystallization phenomenon show that the fres h sample crystallizes much later than the others; the sample aged at 7 0 degrees C takes the shortest time to crystallize, whereas intermedia te behavior is shown by the sample aged at room temperature. This resu lt was correlated with the initial structural organization of the glas sy amorphous samples.