The complex crystalline orientation character of injection molded high density polyethylene was examined. The principal axes and level of orientation along these axes were evaluated using wide angle x-ray diffraction pole figure analyses for various injection molding conditions. The principal axes of each layer were determined by means of ellipsoidal representations from wide angle x-ray diffraction pole figure data. It has been found that the principal axes of crystalline orientation do not exactly coincide with the flow direction. The crystalline orientation state for each layer was evaluated in terms of biaxial orientation factors with appropriate principal axes of orientation. The general behavior of crystalline orientation indicates b-axis orientation normal to the wall and perpendicular to the flow and width directions and c, a-axes biaxial orientation in the plane of the flow and width directions. A mechanism leading to this distribution of crystalline axes is discussed.
© 1992, Carl Hanser Verlag, Munich