Structure evolution and properties enhancement of polyamide-6/polyamide-1010 films under uniaxial and biaxial stretching

The effect of stretching process on the structures and properties of the stretch-oriented PA6/PA1010 film was investigated during the uniaxial and biaxial stretching. The results showed that the PA6/PA1010 cast film exhibited beta-form crystals, and the uniaxial stretching induced the beta -> alpha + gamma phase transition and preferential orientation along the stretching direction, while the beta -> alpha phase transition and no preferential orientation were observed during the biaxial stretching process. Meanwhile, the melting temperature and crystallinity of PA6 in uniaxially and biaxially stretched PA6/PA1010 films were improved with the increasing stretching ratios, thus creating a much more tortuous pathway for the diffusion of oxygen molecules to enhance the oxygen barrier property of the stretched films after uniaxial and biaxial stretching. The morphological analysis showed that the PA1010 particles were oriented and deformed along the stretching direction and no obvious debonding and voids were observed at the interface. In addition, the mechanical properties of the stretched films were closely dependent upon the stretching ratios. It was found that the tensile strength of the biaxially stretched PA6/PA1010 films with stretching ratio of 3.5 x 3.5 in MD and TD exhibited about 1.7 times and 2.2 times higher than that of the PA6/PA1010 cast film, respectively.