The thermo-oxidative aging behaviors of Nylon 1010 films were studied by various analytical methods,such as measuring the chromaticity,relative viscosity,carbonyl index,UV absorbance at 280 nm and elongation at break ...The thermo-oxidative aging behaviors of Nylon 1010 films were studied by various analytical methods,such as measuring the chromaticity,relative viscosity,carbonyl index,UV absorbance at 280 nm and elongation at break of the aged films.The thermo-oxidative aging plots of the results obtained via these various methods at different temperatures are subjected to the time-temperature superposition analysis,which are found to be well superposed.The b＊ values are used as X axis and the other results,i.e.,relative viscosity,carbonyl index,UV absorbance at 280 nm and elongation at break,are used as V axis,respectively.The relationship between the b values and the other results is obtained,from which we can derive the changes of physical and chemical properties at different b＊ values.Since the b＊ values can be quickly determined by using a portable spectrophotometer,the on-line evaluation of the thermo-oxidative aging of Nylon 1010 can be realized.展开更多
A long-term （about nine months） isothermal degradation experiment of two different commercial polylactide （PLA） samples used for food packaging was carried out at a relatively low temperature （423 K）. Thermooxid...A long-term （about nine months） isothermal degradation experiment of two different commercial polylactide （PLA） samples used for food packaging was carried out at a relatively low temperature （423 K）. Thermooxidative degradations of the same polymers were carried out in a thermogravimetric （TG） analyser, at higher temperatures （453 K 〈 T 〈 523 K）, under isothermal heating conditions. The obtained set of experimental TG data was used to determine the apparent activation energy （Ea） of degradation through two isothermal kinetic methods. The results from long-term experiment evidenced considerable mass loss for both PLA samples in the investigated period, but the experimental data were not in agreement with those from the short-term degradations at higher temperatures, thus suggesting a different degradation kinetics, and, then a low reliability of the lifetime predictions for polymers in service or degradation forecasts for the end of their life based on experiments at higher temperatures.展开更多
文摘The thermo-oxidative aging behaviors of Nylon 1010 films were studied by various analytical methods,such as measuring the chromaticity,relative viscosity,carbonyl index,UV absorbance at 280 nm and elongation at break of the aged films.The thermo-oxidative aging plots of the results obtained via these various methods at different temperatures are subjected to the time-temperature superposition analysis,which are found to be well superposed.The b＊ values are used as X axis and the other results,i.e.,relative viscosity,carbonyl index,UV absorbance at 280 nm and elongation at break,are used as V axis,respectively.The relationship between the b values and the other results is obtained,from which we can derive the changes of physical and chemical properties at different b＊ values.Since the b＊ values can be quickly determined by using a portable spectrophotometer,the on-line evaluation of the thermo-oxidative aging of Nylon 1010 can be realized.
文摘A long-term （about nine months） isothermal degradation experiment of two different commercial polylactide （PLA） samples used for food packaging was carried out at a relatively low temperature （423 K）. Thermooxidative degradations of the same polymers were carried out in a thermogravimetric （TG） analyser, at higher temperatures （453 K 〈 T 〈 523 K）, under isothermal heating conditions. The obtained set of experimental TG data was used to determine the apparent activation energy （Ea） of degradation through two isothermal kinetic methods. The results from long-term experiment evidenced considerable mass loss for both PLA samples in the investigated period, but the experimental data were not in agreement with those from the short-term degradations at higher temperatures, thus suggesting a different degradation kinetics, and, then a low reliability of the lifetime predictions for polymers in service or degradation forecasts for the end of their life based on experiments at higher temperatures.
