Experimental studies and molecular modelling of the stress-optical and stress-strain behaviour of poly(ethylene terephthalate). Part III: Measurement and quantitative modelling of birefringence-strain, stress-strain and stress-optical properties

The results given by Kuhn and Grün theory are compared with those given by the MC modelling. The expected shortcomings of Kuhn and Grün theory are found. However, distinct from the behaviour reported previously for polyethene, the theory can be used to evaluate, semi-empirically, the stress-optical coefficient of PET.