The biaxial stretching film of polyamide 6 (PA6) is widely used for food and industrial products packaging. It is expected to improve stretchability, impact strength, tensile strength, and thermoformability for a larger market. So, in this research, the stretching methods were investigated in terms of dynamics and structure development for the biaxial stretching films. There are three different stretching methods which can produce PA6 films, namely the simultaneous biaxial stretching, the sequential biaxial stretching, and the double bubble tubular process. The physical properties of PA6 film are very much influenced by the biaxial stretching process. But there are no reports which described the difference among the three stretching methods and film properties. For this reason, the higher order structure and stretching behaviors of the three stretching methods were studied. As a result, the sequential biaxial stretching showed strong stretched effect and molecular orientation in the transverse direction (TD) and poor film thickness uniformity, because the strong hydrogen bonds were created during the machine direction (MD) stretching and high stretching stress in the TD stretching was required. In the simultaneous biaxial stretching, the molecular orientation was equal both in the MD and in the TD of the stretched plane. The double bubble tubular process produced well‐balanced film and equal orientation in any direction in terms of the phase difference in the plane of film. The biaxially oriented PA6 film having good stretchability and high physical properties was also investigated.

The biaxial stretching film of polyamide 6 (PA6) is widely used for food and industrial products packaging, because it has good physical properties, such as high toughness and gas barrier properties. It is expected to improve gas barrier and easy straight cut performance for a larger market such as food packaging. So, in this research, blends of poly(m‐xylene adipamide) (MXD6) to PA6 which are immiscible were investigated in terms of dynamics and structure development for biaxial stretching films. For this reason, the higher order structure and stretching behaviors of the blends were studied. As a result, blends of MXD6 to PA6 which had cylindrical structures improved the properties of easy straight cut and high barrier, but did not have good stretchability and film thickness uniformity. For these reasons, they were studied to develop the biaxial stretching film of polyamide which improved stretchability and film thickness uniformity. Furthermore, blend effects of MXD6 to PA6 and dynamics analyses were investigated.

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