Elucidating Structural Variations at Heterogeneous Interfaces in Polymer Blends Using Evolved Gas Analysis with Time-of-Flight Mass Spectrometry Under Field Ionization

Abstract

We present a novel method, viz., evolved gas analysis with time-of-flight mass spectrometry (EGA-TOFMS) using field ionization, for analyzing the molecular-scale structural variations at heterogeneous interfaces in polymer blends. EGA-TOFMS enables the acquisition of temperature-dependent high-resolution mass spectra of the pyrolysis products derived from each component of the blends. However, the inherent complexities of these spectra make their interpretation significantly challenging. To address this issue, we developed a filtered Kendric Mass Defect (filtered KMD) technique that selectively isolates signals corresponding to the pyrolysis products of individual components. Additionally, the elected ion current curve, constructed by summing the ion intensities identified using filtered KMD, was used to analyze the pyrolysis behavior of each component. The utility of these techniques is demonstrated using a ternary polymer blend composed of polypropylene (PP), polyamide 6 (PA6), and a maleic anhydride-grafted styrene–ethylene butylene–styrene triblock copolymer (MASEBS), denoted as PP/PA6/MASEBS. Pyrolysis product analysis revealed that MASEBS chemically interacts with PA6, effectively functioning as a compatibilizer. Incorporating 1 wt % MASEBS enhanced the interfacial compatibility and mechanical properties of PP/PA6/MASEBS, whereas higher loadings resulted in the accumulation of excess unreacted MASEBS, reducing the performance. Our analytical framework offers insights into the structure–property relationships of complex polymer systems.