Effect of a Glassy-Glassy Polymer Interface on the Physical Aging of Polystyrene Pubblico

Abstract

Polymers that have been cooled below their glass transition temperature (Tg) are
amorphous, non-equilibrium solids. Because they are out of equilibrium polymer glasses
experience a densification known as physical aging. Here, a thermal reset protocol for
use in measuring the physical aging of polystyrene (PS, Tg=100 degrees C) in a multilayer
polymer film is discussed. Aging rates for single layer bulk films of PS and
polycarbonate (PC, Tg=145 degrees C) supported on silicon substrates were measured using
ellipsometry to test the ability of the protocol to accurately measure physical aging in PS
while minimizing aging in PC. Bilayer polymer films were created consisting of PC on
PS all supported on silicon. The aging rate of PS in the bilayer system was measured
using ellipsometry and found to be consistent with single layer PS values. This newly
established protocol may be used for probing the effects on PS of a glassy interface with
PC.

Table of Contents

Contents
1 Introduction 1
1.1 Glass Transition 1
1.2 Physical Aging 3
1.3 Goal 3
2 Background 4
2.1 Permeability of Gas Separation Membranes 4
2.2 Differential Scanning Calorimetry 5
2.3 Forced Assembly of Nanolayers 6
2.4 Glassy-glassy Interfaces in Polymer Systems 7
2.5 Ellipsometry 10
2.6 Tg and Aging of PS 15
3 Investigating the Physical Aging Behavior of PC/PS Bilayer Films by
Ellipsometry 19
3.1 Procedure 19
3.1.1 Production of Single Layer PS and PC films 20
3.1.2 Production of the Bilayer System 20
3.1.3 Physical Aging 21
3.2 Thermal Reset Protocol 21
3.3 Bilayer Aging Measurements 24
4 Conclusions and Future Work 26
Bibliography 28

About this Master's Thesis

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School	Laney Graduate School
Department	Physics
Degree	MS
Submission	Master's Thesis
Language	English
Research Field	Physics, Condensed Matter
Parola chiave	Polymers
Committee Chair / Thesis Advisor	Roth, Connie, Emory University
Committee Members	Weeks, Eric, Emory University Warncke, Kurt, Emory University

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