ANISOTROPIC ORIENTATION OF THE AMOPPHOUS CHAIN IN DRAWN FILMS

Abstract

The orientation of amorphous chains of uniaxially drawn linear polyethylene film was investigated by the method of fluorescence polarization to study the anisotropy of orientation in the plane perpendicular to the draw axis.
In the measurement of fluorescence, the incident exciting beam was directed perpendicular to the draw axis but at various angles to the film plane. A fluorescence “dichroic” ratio R=I_??_(0°)/I_??_(90°) was used in the quantitative evaluation of the orientation of amorphous chains.
The intensities of the polarized components of fluorescence vary with the incident angle of the exciting light beam in the annealed specimen, whereas in the case of as-darwn specimen, those intensities are independent of the angle.
In the annealed specimen, the dichroic ratio R has higher value in the through direction than in the edge direction.
These results show anisotropic orientation of amorphous chains in the plane perpendicular to the draw axis.
This orientation is related to that of the crystal interfaces. Results of the polarized IR measurements provided an additional evidence for this anisotropic orientation of the amorphous region. The mode of amorphous orientation in the plane which is parallel to the direction of draw and normal to the film plane, seems to be uniaxial symmetry and not the biaxial one which may be expected from the orientation of crystal interfaces.