Using Raman spectroscopic imaging for non-destructive analysis of filler distribution in chalk filled polypropylene

A feasibility study on using Raman spectral imaging for visualization and analysis of filler distribution in chalk filled poly-propylene samples has been carried out. The spectral images were acquired using a Raman spectrometer with 785 nm light source.Eight injection-molded samples with concentration of chalk 25% and 50% were used in the experiment. Two methods for spectralunmixing were applied to the images and both revealed almost identical distribution maps over the samples’ surface. The maps alsocorrelated with the ones obtained for several separated peaks, typical for the chalk and the polypropylene. The revealed distributionpatterns show the same trend for each concentration level and agree with theoretical explanation of plastic flow into an injectionmolding tool.