Texture and Strength Evolution inDeformed Polypropylene

Semicrystalline polypropylene samples with high concentrations of crystallinity (≳62%) are deformedin uniaxial compression at different temperatures and different strain rates. The orientation changes ofthe crystalline part of the material are analyzed using X-ray diffraction methods. Pole figureevaluation is used to obtain information about the crystal structure, the geometry of slip, and itscorrelation with the characteristic of strength evolution in polymers. The contribution of thecrystalline part of the material to plastic flow is estimated and the textures are related to thecharacteristic effects in plastic and visco-elastic response of the material during deformation andsubsequent stress relaxation. The observed texture effects can be explained by the rotation ofcrystallographic c -axis (backbone axis) normal to the compression direction at high temperatures in aplanar slip mode. The stress/strain and relaxation behavior of the material is interpreted as acombination of viscoelastic flow of amorphous volume and irreversible plastic flow of the crystallinepart which contributes to an orientation dependence of deformation and stress relaxation.