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
An infrared dichroism study on the orientation of PS in the shear induced ordered structure in PS/montmorillonite nanocomposite was carried out. The results showed that the phenyl ring oriented apparently parallel to ...An infrared dichroism study on the orientation of PS in the shear induced ordered structure in PS/montmorillonite nanocomposite was carried out. The results showed that the phenyl ring oriented apparently parallel to the film surface, whereas no obvious orientation of the aliphatic chain could be observed. On the basis of both of our previous and present investigations, a possible formation mechanism was presented. [WT5HZ]展开更多
Photo-oxidative degradation is critical to polymer materials. A UV photo-oxidation study on polyamide 6/montmorillonite nanocomposite was carried out by FTIR technique. Through the comparison of the infrared spectra o...Photo-oxidative degradation is critical to polymer materials. A UV photo-oxidation study on polyamide 6/montmorillonite nanocomposite was carried out by FTIR technique. Through the comparison of the infrared spectra of PA6 and PA6/MMT nanocomposite during different times of UV irradiation, it is indicated that the rate of photo-oxidation of PA6/MMT nanocomposite is faster than that of PA6.展开更多
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).
文摘An infrared dichroism study on the orientation of PS in the shear induced ordered structure in PS/montmorillonite nanocomposite was carried out. The results showed that the phenyl ring oriented apparently parallel to the film surface, whereas no obvious orientation of the aliphatic chain could be observed. On the basis of both of our previous and present investigations, a possible formation mechanism was presented. [WT5HZ]
文摘Photo-oxidative degradation is critical to polymer materials. A UV photo-oxidation study on polyamide 6/montmorillonite nanocomposite was carried out by FTIR technique. Through the comparison of the infrared spectra of PA6 and PA6/MMT nanocomposite during different times of UV irradiation, it is indicated that the rate of photo-oxidation of PA6/MMT nanocomposite is faster than that of PA6.
