Optical and Mechanical Measurements to Characterize Injection Molded Polypropylene Plates

By the determination of birefringence and elongation at break as functions of the distance from the surface detailed informations are obtained about the states of orientation of the molecules in injection molded polypropylene plates. Both, the birefringence profile and the profile of elongation at break in the cross-section of the plates, exhibit the skin/core structure typically for injection molded polypropylene articles. An analysis of the results of two polypropylene grades molded at different processing conditions shows a good agreement of both methods.