Investigation on the creep behavior of PA6 film based on the fractional differential model

Abstract

A fractional Burgers model was proposed to investigate the creep behavior of Polyamide 6 (PA6) film. The creep tests at various conditions were conducted on dynamic mechanical analysis (DMA) tester, and the strain-time ( ∊- t) curves of deformation were analyzed by the derived model. The results indicated that the fractional Burgers model had a better performance than the classical integer-order model in simulating the deformation of PA6 film. Parameters analysis showed that the stress facilitated the transformation from viscoelastic deformation to the viscoplastic one under ambient condition. Whereas, at the state of higher temperature, the deformation could be directly activated as the viscoplastic deformation. The softening effect of PA6 film was found to be related to the expansion of viscoplastic units during stretching. Also, the fluidity of the viscoelastic units was greater than that of the viscoplastic units. Through the analysis of dynamic rheological parameters, we speculated that the variation of loss factor may come from the evolution of viscoelastic units.