Modeling elongational viscosity of polystyrene Pom-Pom/linear and Pom-Pom/star blends

The elongational rheology of blends of a polystyrene (PS) Pom-Pom with two linear polystyrenes was recently reported by Hirschberg et al. (J. Rheol. 2023, 67:403–415). The Pom-Pom PS280k-2x22-22k with a self-entangled backbone ( M w,bb = 280 kg/mol) and 22 entangled sidearms ( M w,a = 22 kg/mol) at...

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Bibliographic Details
Published in:Rheologica acta 2023-09, Vol.62 (9), p.433-445
Main Authors: Hirschberg, Valerian, Lyu, Shan, Schußmann, Max G., Wilhelm, Manfred, Wagner, Manfred H.
Format: Article
Language:English
Subjects:
Characterization and Evaluation of Materials
Chemistry and Materials Science
Complex Fluids and Microfluidics
Dilution
Elongation
Food Science
Fractions
Materials Science
Mathematical models
Mechanical Engineering
Modelling
Original Contribution
Parameters
Polymer blends
Polymer Sciences
Polymers
Polystyrene resins
Rheological properties
Rheology
Soft and Granular Matter
Strain hardening
Stress functions
Superhigh frequencies
Topology optimization
Viscosity
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Summary:The elongational rheology of blends of a polystyrene (PS) Pom-Pom with two linear polystyrenes was recently reported by Hirschberg et al. (J. Rheol. 2023, 67:403–415). The Pom-Pom PS280k-2x22-22k with a self-entangled backbone ( M w,bb = 280 kg/mol) and 22 entangled sidearms ( M w,a = 22 kg/mol) at each of the two branch points was blended at weight fractions from 75 to 2 wt% with two linear polystyrenes (PS) having M w of 43 kg/mol (PS43k) and 90 kg/mol (PS90k), respectively. While the pure Pom-Pom shows strong strain hardening in elongational flow (SHF > 100), strain hardening (SHF > 10) is still observed in Pom-Pom/linear blends containing only 2 wt% of Pom-Pom. The elongational start-up viscosities of the blends with Pom-Pom weight fractions above 10 wt% are well described by the Molecular Stress Function (MSF) model, however, requiring two nonlinear fit parameters. Here we show that quantitative and parameter-free modeling of the elongational viscosity data is possible by the Hierarchical Multi-mode Molecular Stress Function (HMMSF) model based on the concepts of hierarchical relaxation and dynamic dilution. In addition, we investigated the elongational viscosity of a blend consisting of 20 wt% Pom-Pom PS280k-2x22-22k and 80 wt% of a PS star with 11 arms of M w,a = 25 kg/mol having a similar span molecular weight as PS43k and similar M w,a as the Pom-Pom. This work might open up possibilities toward polymer upcycling of less-defined polymers by adding a polymer with optimized topology to gain the intended strain hardening, e.g., for film blowing applications. Graphical Abstract
ISSN:0035-4511
1435-1528
DOI:10.1007/s00397-023-01411-1