Pheonomenological analysis of polymer chain orientation in semicrystalline polymers during fabrication process

A phenomenological analysis of the crystalline orientation of a semicrystalline polymers and the orientation of polymer melts prior to the onset of crystallization was proposed. A generalized linear relationship between the second order tensors representing the orientations of the melt and the crystallized states was developed using fourth rank tensor W*(ijkl). The crystalline orientation factors were derived using W*(ijkl) tensor and the rheo-optical law for the polymer melt. Previous experimental observations such as the jump of crystalline orientation level and the change of orientation mode compared with the predicted values from the rheo-optical law can be described by our approach. The values of W-11 and W-12 for melt spun high density polyethylene fiber were 20 and -9.5, respectively. Those values for isotactic polypropylene fibers were 26 and -12.5, respectively.