Macromolecular Branching from General Rigid Bead-Rod Theory
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Authors
Coombs, Steacy
Date
Type
thesis
Language
eng
Keyword
Complex viscosity , Cole-Cole plots , Complex modulus , Branching , Star-branched macromolecules , Rheology
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Abstract
One of the great fascinations in polymer science and engineering is how macromolecular branching can impart elasticity to polymeric liquids. In this thesis, we use macromolecular theory that relies entirely on flow orientation to explain the rheology of polymeric liquids. Specifically, we use general rigid bead-rod theory to explain the effects of: (a) backbone-branching on Cole-Cole curves, and (b) star-branching on complex viscosity. We employ general rigid bead-rod theory for (a) structure-by-structure, and more ambitiously for (b), analytically.
In the first part of this thesis, we find that parametric plots of the imaginary versus real parts of the complex viscosity may depend neither on temperature, nor on average molecular weight. Moreover, for fixed polydispersity, these Cole-Cole curves amplify both rightward and upward with long-chain branching content. In this paper, we find that general rigid bead-rod theory [1] can explain these rightward and upward amplifications. We explore the effects of branching along a straight chain in small-amplitude oscillatory shear flow. Specifically, we explore the number of branches, branch length, branch position and branch distribution.
In the second part of this thesis, the complex viscosity of planar star-branched polymers has been derived from general rigid bead-rod theory, but only for singly-beaded arms. Here, we explore the respective roles of branch functionality, arm length and non-planar arrangements, analytically from general rigid bead-rod theory. For non-planar arrangements, we include polyhedral, both regular and irregular. Further, for all structures, we compare with and without the central bead. We fit the theory to complex viscosity measurements on polybutadiene solutions, one quadrafunctional star-branched, the other unbranched, of the same molecular weight (M_w=200,000 g/gmol). We learn that when general rigid bead-rod theory is applied to quadrafunctional polybutadiene, a slightly irregular center-beaded tetrahedron of interior angle 134º is required (with 1,360,000 g/gmol per bead) to describe its complex viscosity behaviour.
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CC0 1.0 Universal
ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.
CC0 1.0 Universal