Monitoring the Chemical Composition of Polyolefins along the Molar Mass Axis with High‐Temperature Size Exclusion Chromatography Coupled with an Infrared Detector (HT SEC‐IR5)

Series of ethylene/1-alkene and ethylene-propylene-diene copolymers are separated with size exclusion chromatography (SEC) at 150°C using 1,2,4-trichlorobenzene as the mobile phase. Methyl (CH3–) methylene (–CH2–) groups in polymer samples monitored specific wavelengths via a filter-based infrared detector (IR5). It is found that ratio CH3/CH2 may increase, be constant, decrease or change irregularly along molar mass axis, depending on sample under investigation. Because profiles very different even for given series synthesized same catalyst, it supposed one more experimental parameters, which not strictly controlled throughout synthesis, responsible these substantial differences chemical composition axis. The correlation between CH3– to –CH2– average investigated well reproducibility measurements limit detection SEC-IR5 evaluated. Coupling SEC advanced IR5-detector enables convenient reliable characterization many polyolefin materials their monitoring help improve quality copolymers.