Deconvolution of Overlapping Thermal Transitions in Polyolefin Blends Through Simultaneous Calorimetry and Raman Spectroscopy

Advanced manufacturing requires precise understanding of polymer structure-property relationships. This precision is challenged by heterogeneous polymer systems, where bulk measurements capture the entire system rather than individual components. These heterogeneous systems can produce overlapping thermal transitions that obscure individual contributions during thermal analysis, whether the heterogeneity arises from chain branching distributions, molar mass dispersity, or blend composition. This challenge is particularly present in recycled polymer feedstocks stemming from mechanical recycling. The current practical constraints of mechanical sorting result in blend compositions with unknown component ratios and molecular architecture distributions. Here we apply combined Raman spectroscopy and differential scanning calorimetry to resolve these overlapping signals in polyolefin blends by adding chemical specificity to thermal analysis. The results are discussed within the appropriate thermodynamic and kinetic frameworks. Additionally, we address technique-specific considerations essential to successful analysis.