Deformation of semicrystalline and molten polyethylene the role of entanglements

Paul, Eva; Heise, B.; Schrodi, W.; Kilian, H. G.

doi:10.1007/bfb0114804

Cited by 5 publications

(2 citation statements)

References 46 publications

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“…Besides the important crystallographic slip of crystallites, two basic modes of interlamellar sliding (shear) and lamellar separation (extension) are known to have a close relationship with the deformation of amorphous chains. , The interlamellar sliding proceeds primarily at the early stage of deformation, resulting in the necking initiation. The further molecular orientation within the thin amorphous layers along with the neck propagation is then constrained by the adjacent lamellae that possess a modulus much higher than that of the amorphous component and operate as multifunctional cross-links. − On the basis of these ideas, we consider that the ideal rubberlike behavior in the amorphous phase may lead to the lamellar separation as a local area is moved along the neck shoulder, if the lamellar fragmentation or microcracking does not occur markedly.…”

Section: Discussionmentioning

confidence: 99%

“…The further molecular orientation within the thin amorphous layers along with the neck propagation is then constrained by the adjacent lamellae that possess a modulus much higher than that of the amorphous component and operate as multifunctional crosslinks. [56][57][58][59][60] On the basis of these ideas, we consider that the ideal rubberlike behavior in the amorphous phase may lead to the lamellar separation as a local area is moved along the neck shoulder, if the lamellar fragmentation or microcracking does not occur markedly.…”

Section: Discussionmentioning

confidence: 99%

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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

2003

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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, f am, 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 shoulder. The orientation function f c in the crystalline phase increases linearly with f am up to f am = 0.3 with a slope of 1.85 for all samples tested. In the neck entity, the crystal orientation may lag behind the amorphous chain orientation due to the enhanced plastic deformations. It is shown that the behavior of the amorphous phase is essential for the averaged lamellar orientation on the mesoscale.

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