Work

Unlocking polyolefin microstructure: Robust 8-angle CEF-MALS workflow for accurate molecular weight and reproducible SCBD profiling

Year: 2025

Type: article

Abstract: Polyolefins such as polyethylene (PE) and polypropylene (PP) require characterization of structural heterogeneities-molecular weight distribution (MWD), short-chain branching distribution (SCBD), and long-chain branching (LCB)-for performance optimization. Crystallization Elution Fractionation (CEF) provides SCBD measurement, while conventional workflows couple it with viscometry for molecular weight estimation. Viscometry is subject to low sensitivity limitations with susceptibility to temperature/pressure fluctuations during CEF analysis. Although multi-angle light scattering (MALS) delivers absolute MW and radius of gyration (Rg) data, technical barriers have limited its integration with CEF. This work couples an eight-angle MALS detector with CEF for the first time and give an access to comprehensive microstructural information of polyolefins with high accuracy in the absolute molecular weight measurement through the entire SCBD profile. Application to commercial polyolefins (LLDPE, IPC, PP-R) reveals the structural features not captured by conventional methods. Key CEF error sources were quantified as solvent delivery (pump flow rate) inconsistencies, temperature fluctuations, and column aging. Mitigation approaches include rational column design (4.6 mm internal diameter to reduce thermal gradients), static cooling implementation, and standardized calibration protocols. This integrated CEF-MALS method facilitates enhanced precision and accuracy in polyolefin microstructure characterization for structure-property modeling and material development.

Source: Journal of Chromatography A

DOI: 10.1016/j.chroma.2025.466620