Crystal structure of uniaxially stretched bio-based polyamide 510 films

The crystal structure changes of PA510 films during uniaxially stretching at 80°C, 110°C, 140°C and 170°C had been investigated as a function of stretching ratio and stretching rate. The stress–strain relationship curves showed that the stress of the PA510 films gradually increased when the stretching ratio increased. The wide-angle X-ray diffraction results verified that only one distinct equator reflection of stretched films was clearly identified at 80°C, 110°C and 140°C, namely γ(100) at 2θ = 20.6°. However, when the stretching temperature reached 170°C, the γ(004), γ(006) and γ(008) crystal form appeared in the meridional direction at λ = 12. Combined with differential scanning calorimeter analysis, it was found that the Xc increased from 7% to 40% as a result of the strain induced crystallization phenomenon and the stretching promoted the appearance of γ crystal form. In addition, the increase in the crystallinity and the molecular chain orientation increased the strength of the PA510 films in the tensile direction. And it also found that the microcracks occurred in the stretched films at high stretching ratio (λ = 12).