Real-time Raman spectroscopy during LDPE/ PP bilayer blown-film extrusion

AbstractThe present study reports on a technique for real-time Raman spectroscopic measurement of crystallinity of the individual components of a bicomponent film (LDPE/PP) during blown-film extrusion. The 1296–1305 cm−1 band, observed predominantly for PE, was slightly masked by the contribution from the PP layer. However, the 809–841 cm−1 band was unique for PP and unaffected by the presence of the PE layer. Thus, Raman spectra for PE/PP bilayer films consist of superimposed spectra of the components with some overlapping peaks but some distinct peaks. These distinct peaks enable successful real-time crystallinity measurement during coextrusion of LDPE/PP films.