New approaches using MW-sensitive detectors in GPC–TREF for polyolefin characterization

For in-depth analyses of polyolefin microstructures, we have installed the MW-specific light scattering (LS) and viscosity detectors into a home-built hybrid GPC–TREF instrument. Data processing capabilities were developed for this triple-detector system to determine (1) polymer long chain branching (LCB) distribution across the GPC-determined molecular weight distribution (MWD) curve, (2) the GPC-Mz and higher-order MW averages with greatly improved precision to complement the rheological results, and (3) the dependence of polymer MW across the TREF-determined short chain branching (SCB) distribution curve. A ‘polymer microstructure plot’ is created from the combined overlays of triple-detector GPC–TREF chromatograms to provide a quick view of detecting subtle sample differences in polymer MW, MWD, SCB or LCB. These results can do much more than the use of only the MI and density values for product development or trouble shooting of polymer end-use properties.