Characterization of the chemical composition distribution of polyolefin plastomers/elastomers (ethylene/1-octene copolymers) and comparison to theoretical predictions

Molecular Dynamics Simulation of Ethylene/Hexene Copolymer Adsorption onto Graphene: New Insight into Thermal Gradient Interaction Chromatography

“…The authors suggest that the difference could be the result of axial dispersion which is the main contributor to peak broadening in conventional chromatographic techniques . This enhanced peak broadening of TGIC profile compared to Stockmayer's distribution was recently confirmed by Arndt et al In this work, we suggest a complementary explanation for this peak broadening. TGIC experiments were conducted for a series of ethylene/hexene copolymers (synthesized with metallocene catalysts) and compared to a series of simulations (using the GROMACS package).…”

Recent Advances in Separation-Based Techniques for Synthetic Polymer Characterization

“…Except for the use of a solvent gradient in HTLC, all of the rest of the techniques use temperature as the main separation knob and share the following experimental steps: The polymer sample is dissolved in a solvent or an isocratic solvent mixture. A fraction of polymer solution is loaded onto a column at high temperature where polymers are still soluble. The polymer solution is fractionated into different components on the substrates based on their CC while the temperature of column is being cooled at a certain rate. Polymer fractions are eluted by raising flow rate and temperature of the column to achieve further separation and detection. The properties of the eluate are measured by a detector or array of detectors, such as DRI, IR, ,, ELSD, or turbidity, to provide a measure of concentration as a function of temperature. The use of multiple detectors provides additional information.…”

“…Polymer fractions are eluted by raising flow rate and temperature of the column to achieve further separation and detection. The properties of the eluate are measured by a detector or array of detectors, such as DRI, IR, ,, ELSD, or turbidity, to provide a measure of concentration as a function of temperature. The use of multiple detectors provides additional information.…”

“…Crystallization-based techniques have been widely used: (1) to understand molecular structure of polymer and polymer blends, for example to investigate effects of tacticity and comonomer content in poly­(1-butene) and polypropylene blends, to compare theoretically modeled CCD vs experimentally measured broadness of CCD at different CC in plastomers and elastomers, and to better understand complicated molecular structure of low density polyethylene (LDPE) with overlapping distributions of LCB and SCB; (2) to correlate molecular structure with performance, such as polyethylene materials in pipe applications and biaxially stretched film for packaging, polypropylene material for a balance of stiffness and toughness, the effect of hexyl branch content of poly­(ethylene-co-octene) on thermal degradation behavior; (3) to correlate process parameters with the molecular structure of products, for example, the effect of processing parameters on the molecular structures of poly­(propylene-co-ethylene) in a single gas phase reactor . The combination of crystallization-based techniques with other separation techniques such as HT-GPC, HT-TGIC, and HTLC has become a recent trend.…”

“…The separation mechanism is based on the adsorption of polymer chains onto the stationary phase, where both enthalpy and entropy contribute to the adsorption according to molecular dynamics simulation with poly­(ethylene-co-hexene) copolymers . Combined with other analytical techniques, HT-TGIC has been used to provide a comprehensive understanding of molecular structures of polymers, such as polymers made by chain walking catalysis, CCD of elastomeric materials, poly­(ethylene-co-octene) copolymers, , and oxidized waxes in adhesive applications. , …”