Pseudo-affine deformation process

Pseudo-affine model, the deformation process of polymers in cold drawing is very different from that in the rubbery state. Elements of the structure, such as crystallites, may retain their identity during deformation. In this case, a rather simple deformation scheme [12] can be used to calculate the orientation distribution function. The material is assumed to consist of transversely isotropic units whose symmetry axes rotate on stretching in the same way as lines joining pairs of points in the bulk material. The model is similar to the affine model but ignores changes in length of the units that would be required. The second moment of the orientation function is simply shown to be ... 

Figure 8.1 5 The crystal orientation of polypropylene fibres and films as a function of the true strain in the deformation process draw temperatures ( ) 135 °C, (a) I 10 °C. The prediction of the pseudo-affine model is shown as a dashed line (from Samuels RJ. Structured Polymer Properties, Wiley, 1974).

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