Berlin 2015 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 64: Flow-Induced Structures in Complex Fluids (with DRG, Deutsche Rheologische Gesellschaft, and DY)

CPP 64.6: Vortrag

Donnerstag, 19. März 2015, 11:00–11:15, C 264

Rheological and SEC characterization of long-chain branched poly(ethylene terephthalate) — •Matthias Kruse, Víctor Hugo Rolón Garrido, and Manfred H. Wagner — Chair of Polymer Engineering/Polymer Physics, Berlin Institute of Technology (Berlin), Fasanenstrasse 90, D-10623 Berlin, Germany

Reactive processing is an effective and economic method to produce customized polymers fulfilling improved or additional properties. We report on reactive extrusion of poly(ethylene terephthalate) (PET) and demonstrate that linear PET can be converted into long-chain branched (LCB) PET via chain extension thereby broadening the range of possible applications. An anhydride and an epoxy based chain extender were employed, which react with the functional end groups of linear PET. Different concentrations of the two tetrafunctional coupling reagents were used to achieve different degrees of branching and to compensate for the degradation of the polymer during extrusion. The formation of LCB was proven by dynamic plate-plate rheometry and leads to a more pronounced shear thinning behavior and an increase in the complex viscosity. The increase of molecular weight and polydispersity are also confirmed by size exclusion chromatography using triple detection (concentration, light scattering and viscosity). The elongational viscosity measurements conducted with a SER device show an unexpected influence of the chain extender on the type of sample rupture at larger extensions, and give clear evidence of different levels of strain hardening with respect to the chain extender content, as quantified by the molecular stress function (MSF) model.