Analysis methodMeasurement of interdiffusion in polymeric materials by applying Raman spectroscopy

Raman spectroscopy was evaluated regarding its specific value in terms of detection of interdiffusion in two-component injection molded parts. Two-component injection molded parts made of four material combinations chosen from polypropylene, styrene based thermoplastic elastomer, polycarbonate, polystyrene and polymethyl methacrylate produced by varying melt temperatures of the second component TM2 were investigated.In principle, Raman spectroscopy was found to be a powerful tool to detect interdiffusion. However, some restrictions arise. These include spatial resolution limit and detection limit. Interdiffusion lengths ranging from below 1 μm-3 μm were determined. Either an increase, a decrease or no change of the interdiffusion length for increasing TM2 was detected. The interdiffusion lengths were compared with the stress and elongation at break obtained by tensile tests. No distinct correlation of interdiffusion length and the mechanical properties was found. However, a high TM2 provoked an increase in the stress and elongation at break.