Terpolymers of N-p-tolylmaleimide(NPTMI), methyl methacrylate(MMA) and acrylonitrile(AN) were synthesized by emulsion polymerization. The thermal properties of the terpolymers were investigated by torsional braid anal...Terpolymers of N-p-tolylmaleimide(NPTMI), methyl methacrylate(MMA) and acrylonitrile(AN) were synthesized by emulsion polymerization. The thermal properties of the terpolymers were investigated by torsional braid analysis, differential scanning calorimetry, thermogravimetric analysis and vicat softening point tester. The results showed that the glass transition temperature(T g) and vicat softening point of the terpolymers increased with the increase of NPTMI content but decreased with the increase of AN content. The initial decomposition temperature(T 0) and the half weight-loss temperature(T 50 ) increased both with increasing NPTMI and AN content. The weight and number average molecular weights were also determined by gel permeation chromatography. The results showed that there was a maximum value at mass ratio 10∶85∶5 of NPTMI/MMA/AN.展开更多
Effects of annealing temperature( T a) and annealing time( t a) on the liquid liquid transition and transition intensity of atactic poly(methyl methacrylate) were studied by means of differential scanning calorimetry....Effects of annealing temperature( T a) and annealing time( t a) 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 T a from 393 to 443 K, T ll shifted to higher temperature with the decrease in transition intensity, on the contrary, when T a was over 443 K, T ll declined and transition intensity increased. When T a kept constant with the increase of t a, T ll and transition intensity varied as the results described above. Moreover, the variation extent of T ll and transition intensity increased with the increase of T a, in other words, the time needed reaching the maximum extent of variation of the two parameters was decreased with the increase of T a. The dependence of T ll 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).展开更多
文摘Terpolymers of N-p-tolylmaleimide(NPTMI), methyl methacrylate(MMA) and acrylonitrile(AN) were synthesized by emulsion polymerization. The thermal properties of the terpolymers were investigated by torsional braid analysis, differential scanning calorimetry, thermogravimetric analysis and vicat softening point tester. The results showed that the glass transition temperature(T g) and vicat softening point of the terpolymers increased with the increase of NPTMI content but decreased with the increase of AN content. The initial decomposition temperature(T 0) and the half weight-loss temperature(T 50 ) increased both with increasing NPTMI and AN content. The weight and number average molecular weights were also determined by gel permeation chromatography. The results showed that there was a maximum value at mass ratio 10∶85∶5 of NPTMI/MMA/AN.
文摘Effects of annealing temperature( T a) and annealing time( t a) 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 T a from 393 to 443 K, T ll shifted to higher temperature with the decrease in transition intensity, on the contrary, when T a was over 443 K, T ll declined and transition intensity increased. When T a kept constant with the increase of t a, T ll and transition intensity varied as the results described above. Moreover, the variation extent of T ll and transition intensity increased with the increase of T a, in other words, the time needed reaching the maximum extent of variation of the two parameters was decreased with the increase of T a. The dependence of T ll 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).
