Diblock copolymers and steric stabilization during flow

• Published in: Journal of macromolecular science. Physics Vol. 37; no. 2; pp. 239 - 253
• Main Author: Lyngaae-Jørgensen, J.
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Philadelphia, PA Taylor & Francis Group 01.03.1998; Taylor & Francis
• Subjects: Applied sciences; Exact sciences and technology; Organic polymers; Physicochemistry of polymers; Properties and characterization; Rheology and viscoelasticity; Polymer blends; Molten state; Shear flow; Diblock copolymer; Methyl methacrylate polymer; Styrene polymer; Experimental study; Compatibilizer; Modeling; Heterogeneous mixture; Rheological properties
• ISSN: 0022-2348; 1525-609X
• DOI: 10.1080/00222349808220469

A hypothesis (theory) has been formulated for steric stabilization during simple shear flow of discrete domains of one polymer A in a continuous phase B by block copolymer addition. A limiting solution found when the molecular weights of the components are high predicts preformed small drops stabilized by block copolymers at the interfaces are stable below a critical shear stress τ cr but unstable above τ cr Interfacial placement in well dispersed blends of PS/PMMA/PS-b-PMMA was deduced by interfacial tension measurement, structure development studies, and viscosityshear rate studies with and without block copolymers. The experimentally determined critical shear stresses show relatively poor reproducibility (SD ± 10%). For measurements at shear stresses larger than the critical values, interesting time effects are observed, whereas scattering signals are constant at shear rates lower than τ cr The hypothesis is not rejected when compared with experimental data from light-scattering measurements during flow.