Study On The Rheology Properties Of Polyamide 6 And Polyamide 6 / SiO₂ Nanocomposites

With modification of polymer nano-technology development, Polyamide6/SiO₂ nanocomposite because of its excellent performance in many fields in favored people, it becomes one of the hot research in the polymer. However, most of people research it by chemical and physical characterization, relatively few of its macro-mechanical properties. As its typical viscoelastic properties, it has a stronger dependence on time, temperature, crystallinity, loading rate and stress, and performance different mechanical properties. In this thesis, such mechanics issues of polyamide6/SiO₂ nanocomposite have been studied and discussed.Apply the quasi-static uniaxial tensile testing to polyamide 6 specimens, while the temperature which distribution at the surface specimens were monitored by a thermal infrared imaging system. The relationships of the neck history of shaping and stable development between the stress and strain were analyzed under the different loading rate, and also calculated the plastic work at different time in the necking history, which transferred into the specimens maximum infrared radiation temperature. Some available results of specimen surface temperature and plastic work at the different loading rate were obtained.Semi-crystalline polymer and amorphous polymer mechanical properties in macroscopic has significant difference because of crystallinity in the polymer. Here, applying crystallinity measurements to the necked specimens which stretched under the different loading rate to study mechanical properties between the macro-and micro-structure.Considering the time effect of the polyamide6/SiO₂ nanocomposite, the creep experiments were carried out under the different stress levels. Then we constructed and analyzed a creep model of polyamide6/SiO₂ nanocomposite, which based on the microscopic theory and experimental data.The experimental data were analyzed in combination with macro-micro creep model, and instantaneous elastic, viscoelastic, and viscous flow parameter values were obtained from the models at room temperature to measure the mechanical behavior of nano fillers from the microstructure. Based macro-micro creep model, the activation volume of polyamide6/SiO₂ nanocomposite under different stress levels were calculatied. And investigated the role of stress in the specimen on the process of molecular chain potential energy activated and the attachment of activation volume, noting that molecular chain with nano particles have different effects on the potential energy barrier.By the macro-and micro-experiments and study on mechanical properties of polyamide 6 and polyamide6/SiO₂ nanocomposite, the aim of this research is mainly to find the way of prediction and modification the macro-and micro-mechanical properties, and provide mechanical supports for the further chemical modification and structure design in the application engineering.