Preparation and Structure-Properties of Simultaneous-biaxially Stretched Cellulose Film.

Cellulose acetate films were uniaxially and simultaneous biaxially stretched at room temperature in the swell-wet agent bath, as previously, and then they were saponificated by alkali aqueous solution. The effects of stretching systems on the molecular orientation and mechanical properties of the stretched cellulose films were examined. Following results were obtained: (1) The molecular chaos of the cellulose films uniaxially stretched with free width showed a uniaxial orientation with cylindrical symmetry around the stretching axis, and the anisotropy of mechanical properties in the machine direction was greater than that of the other samples by stretched systems. (2) For the uniaxially stretched cellulose films with constant width, the molecular chaos showed a uniplanar-axial orientation, in which the chaos are oriented uniaxially to the stretching axis and also a certain crystallo-graphic plane is parallel to the film surface, and the anisotropy of mechanical properties was smaller than that of the films uniaxially stretched with free width. (3) For the simultaneous biaxially stretched cellulose films, the molecular chaos showed a uniplanar orientation, which are random orientation within the films along with parallel to film surface, at all stretch ratios. The balanced mechanical properties, which were isotropic in the film plane regardless of the stretch ratio, were improved by stretching.