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Deformation Mechanisms Of Polymer Thin Films By Simultaneous Kinetic Measurement Of Microscopic Infrared Dichroism And Macroscopic Stress. 2. Molecular Orientation During Necking Process Of Isotactic Polypropylene
Published 2003 · Chemistry
The molecular orientations in the crystalline and the amorphous phases in a quenched isotactic polypropylene (iPP) film with a smectic structure are studied using an instrument constructed for simultaneous kinetic measurement of microscopic infrared (MicIR) dichroism from a predetermined sampling area with a size of 200 × 200 μm2 and macroscopic stress of film uniaxially stretched at a constant elongation rate at 30 °C. Local deformation behavior in the sampling area is determined for one sample using a method of photogrammetry. During the passage of the necking through the sampling area, the local extension ratio λ(t) increases fast from 1.5 to 5, which induces the rapid orientation of iPP chains in both the crystalline and the amorphous phases. The orientation function of the amorphous phase, fam, from the mesoscale deformation of the sampling area is found to be well described by the pseudo-affine deformation mechanism, since the local area shrinks anisotropically during the passage of the neck shoulde...