In order to describe orientations of normals to (hkl) crystallographic planes in biaxially oriented polyamide 11 films, a pseudo-orthorhombic unit cell (a' = hydrogen bonding plane normal, c' = parallel to the chain axis, b' = perpendicular to the a'-c' plane) was developed.
Table 1 Angles Between Axes of Pseudo-Orthorhombic Unit Cell and Pole of Selected Crystallographic Planes of Triclinic [alpha]/Monoclinic [beta] Polyamide 11 Crystals.
The directions of orientations of crystallographic plane normals are retained after annealing.
In contrast to the original sample, which is nearly isotropic [ILLUSTRATION FOR FIGURE 6A OMITTED], one can note in the stretched PEEK specimens [ILLUSTRATION FOR FIGURES 6B to 6D OMITTED] that the normals to the (100) crystallographic planes rotate progressively towards the plane perpendicular to the tensile axis [at [[Epsilon].
In this simulation, the following simplifications are made: i) the lamellae are supposed to obey a rigid-viscoplastic behavior (no Van der Waals elasticity taken into consideration at this step), ii) the crystal plasticity is controlled by the activation of glide systems on crystallographic planes containing the chain axis, and iii) the rubber elasticity of the amorphous phase is temporarily neglected.