CAJ | 학술논문

Effects of annealing temperature(Ta) and annealing time(ta) on the liquid-liquid transition and transition intensity of atactic poly(methyl methacrylate) were studied by means of differential scanning calorimetry. With the increase of Ta from 393 to 443 K, Tll shifted to higher temperature with the decrease in transition intensity, on the contrary, when Ta was over 443 K, Tll declined and transition intensity increased. When Ta kept constant with the increase of ta, Tll and transition intensity varied as the results described above. Moreover, the variation extent of Tll and transition intensity increased with the increase of Ta, in other words, the time needed reaching the maximum extent of variation of the two parameters was decreased with the increase of Ta. The dependence of Tll and transition intensity on annealing conditions may be explained by the formation of local ordered structure, i.e. stereocomplex, during the annealing process by means of Van der Waals forces between isotacitic and syndiotactic segments of the same or different chains of atactic poly(methyl methacrylate).