Structure and Properties of Glassy Polymers

467 Pages·1998·0.75 MB·English

by  Martin R. Tant and Anita J. Hill (Eds.)

710
ACS SYMPOSIUM SERIES
Structure and Properties
of Glassy Polymers
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02 Martin R. Tant, EDITOR
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1 Eastman Chemical Company
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acs.199 Anita J. Hill, EDITOR
pubs.y 28, Commonwealth Scientific and Industrial Research Organisation
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ctober 29, ublication Developed from a symposium sponsored by the
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Division of Polymeric Materials: Science and Engineering
at the 213th National Meeting
of the American Chemical Society,
San Francisco, California,
April 13-17, 1997
American Chemical Society, Washington, DC
In Structure and Properties of Glassy Polymers; Tant, M., et al.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1999.
TA 455 .P58S7444 1998 c.1
Structure and properties of
glassy polymers
Library of Congress Cataloging-in-Publication Data
Structure and properties of glassy polymers / Martin R. Tant, editor, Anita J.
Hill, editor.
p. cm.—(ACS symposium series, ISSN 0097-6156 ; 710)
"Developed from a symposium sponsored by the Division of Polymeric
Materials: Science and Engineering at the 213th National Meeting of the
American Chemical Society, San Francisco, California, April 13-17,1997."
1
0
w0 Includes bibliographic references and index.
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71 ISBN 0-8412-3588-0
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9 1. Polymers. 2. Amorphous substances.
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bk- I. Tant, Martin R., 1953- . II. Hill, Anita J. III. American Chemical
21/ Society. Division of Polymeric Materials: Science and Engineering. IV.
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1 American Chemical Society. Meeting (213th : 1997 : San Francisco, Calif.) V.
0.
1 Series.
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acs.org 1999 | d T62A04.515'9.P25—8Sd7c72414 49 189-9286 922 CIP
pubs.y 28,
p://uar The paper used in this publication meets the minimum requirements of American National Standard for
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In Structure and Properties of Glassy Polymers; Tant, M., et al.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1999.
Advisory Board
ACS Symposium Series
01 Mary E. Castellion Omkaram Nalamasu
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0.fw ChemEdit Company AT&T Bell Laboratories
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07 Arthur B. Ellis Kinam Park
8-
99 University of Wisconsin at Madison Purdue University
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k-
1/b Jeffrey S. Gaffney Katherine R. Porter
2 Argonne National Laboratory
0 Duke University
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0.
1 Gunda I. Georg
org 9 | doi: University of Kansas TDhoe uDgAlSa sG Aro.u Spm, Initch.
acs.199 Lawrence P. Klemann Martin R. Tant
pubs.y 28, Nabisco Foods Group Eastman Chemical Co.
p://uar Richard N. Loeppky
2 | htte: Jan University of Missouri PMarikceh-Daealv iDs .P hTaarymlaocre utical
201Dat Cynthia A. Maryanoff Research
ctober 29, ublication R. WRe.s eJaorhcnhso Inn sPtihtuatrem aceutical ULneirvoerys iΒty. oTf oMwicnhisgeannd
OP Roger A. Minear
William C. Walker
University of Illinois
at Urbana-Champaign DuPont Company
In Structure and Properties of Glassy Polymers; Tant, M., et al.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1999.
Foreword
THE ACS SYMPOSIUM SERIES was first published in 1974 to provide
a mechanism for publishing symposia quickly in book form. The pur­
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00 pose of the series is to publish timely, comprehensive books devel­
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0.f oped from ACS sponsored symposia based on current scientific re­
71 search. Occasionally, books are developed from symposia sponsored
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10. terest to the audience. Some papers may be excluded in order to better
oi: focus the book; others may be added to provide comprehensiveness.
org 9 | d When appropriate, overview or introductory chapters are added.
acs.199 Drafts of chapters are peer-reviewed prior to final acceptance or re­
pubs.y 28, jection, and manuscripts are prepared in camera-ready format.
p://uar As a rule, only original research papers and original review pa­
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In Structure and Properties of Glassy Polymers; Tant, M., et al.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1999.
Preface
This volume was developed from selected contributions to the Symposium on
Structure and Properties of Glassy Polymers, sponsored by the Division of
Polymeric Materials: Science and Engineering (PMSE) and held during the 1997
Spring ACS Meeting in San Francisco. This three-day symposium provided a
01 forum for lively discussions on diverse topics ranging from ionic transport in
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pr polymer glasses to glass formation of spatially confined molecules. The discus­
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71 sions continuously evoked the principles of glassy polymer physics to interpret
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8- new or recent data on physical, mechanical, electrical, and transport properties.
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1 Application of recent and developing mechanistic models (in place of phenome-
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b nological models) to such newly emerging data showed promise for developing
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02 unified interpretations of glassy behavior. It became clear during the symposium
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0. that only by obtaining a fundamental understanding of the underlying physics of
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oi: polymeric glasses will polymer scientists and engineers be able to develop the
pubs.acs.org y 28, 1999 | d eabrtiileitsTy dh teioss ibtraeoidolo kfro, trlh iskep ees tctrhiufeic ctsu ayrpmep palioncsdai tuisomtan,ts e.i s o of rtghaen pizoeldy minetro gfliavses steoc aticohnise:v eP hthyes icpsr oopf ­
p://uar Glassy Polymers, Molecular Mobility and Relaxations in the Glassy State,
2 | htte: Jan Panh yisnitcraold uAcgtoinryg, cMhaepctehra nwicriatlt ePnr obpye rtthiees ,e daintodr sT. raWnsep okrnt oPwr oopfe nrtoie so thaenrd bionocklu dtheast
201Dat covers such a diverse range of topics concerning the structure and properties of
ober 29, blication gpllaascseyd pino lyanmye rosf isne svuecrahl asne cutpio-ntos-.d aTteh ufass, hrieoand.e rSs oamree ecnhcaoputerargs ecdo utlod phearvues eb etehne
OctPu entire book for only then will a complete picture of glassy polymer physics

emerge. Note that the physics of polymer melts is not covered except where an
understanding is needed of, for example, the approach toward the glass transi­
tion or where comparing glassy behavior to that of the liquid.
We express our deep gratitude to the sponsors of the symposium: Eastman
Chemical Company, Commonwealth Scientific and Industrial Research Organi­
zation (CSIRO) Division of Manufacturing Science and Technology, EG&G
Ortec, the Petroleum Research Fund of the American Chemical Society, and the
ACS Division of Polymeric Materials: Science and Engineering, Inc. We are
also grateful for the expert assistance of Anne Wilson of the ACS Books
ix
In Structure and Properties of Glassy Polymers; Tant, M., et al.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1999.
Department. In addition, the editors acknowledge Georgina Roderick of CSIRO
for her assistance with the cover design. Contributors to the symposium and to
the volume are thanked for sharing their work and opinions with the scientific
community.
MARTIN R. TANT
Research Laboratories
Eastman Chemical Company
Kingsport, TN 37662
ANITA J. HILL
CSIRO
Manufacturing Science and Technology
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0 Clayton, Victoria 3168 Australia
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In Structure and Properties of Glassy Polymers; Tant, M., et al.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1999.
Chapter 1
The Structure and Properties of Glassy Polymers
An Overview
Anita J. Hill1 and Martin R. Tant2
1CSIRO Manufacturing Science and Technology, Private Bag 33, South Clayton
MDC, Clayton, Victoria 3169, Australia
2 Research Laboratories, Eastman Chemical Company, P.O. Box 1972,
1 Kingsport, TN 37662
0
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ch An overview of the physics of glassy polymers and the relationships
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1 between molecular mechanisms and macroscopic physical, mechanical
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8-0 and transport properties of polymer glasses is presented. The
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9 importance of local translational and/or rotational motions of molecular
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k- segments in the glass is discussed in terms of the implications for
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21/ thermodynamic descriptions of the glass (configurational states and
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1 energy surfaces) as well as history dependent properties such as
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pubs.acs.y 28, 199 aGplpasliscya tiopnolsy mfroerms satrreu cttuercahl no(hloygpeicrablalryic imwpinodrtoawnts ) atcor oeslse ctthroen icg a(miounti co cfo nmdautcetroiarsls,
p://uar surface coatings for printed circuit boards) to environmental (membranes for industrial
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201Dat and the range of non-equilibrium states available to the polymer. Early theoretical
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behaves as a glass) is necessary in order to determine the configurational state and
hence physical (and possibly mechanical and transport) properties of the glass. The
contributions to this book and other symposia compilations (8-12) illustrate the quest
for theories and characterization techniques that adequately predict and measure
phenomena responsible for the mechanical, electrical, magnetic, physical and transport
properties of polymer glasses.
The Glass Transition
Glasses can be easily formed from non-crystallizable polymers and can be formed as
well from crystallizable polymers if the cooling rate from the melt to below the glass
©1998 American Chemical Society 1
In Structure and Properties of Glassy Polymers; Tant, M., et al.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1999.
2
transition temperature is sufficiently rapid. The glass transition, or glassy
solidification, has been described as either a thermodynamic transition or a kinetic
phenomenon (13). Glassy solidification shows similarities to a formal second-order
transition in the pressure dependence of T; however, as pointed out by Rehage and
g
Borchard (14) internal thermodynamic equilibrium does not exist on both sides of T
g
(the Ehrenfest relationships do not hold) making it impossible to describe the
solidification process as a formal second order transition. Alternatively, the kinetic
argument suggests that our measurement techniques and their characteristic
frequencies define the phenomenological glass transition temperature. As the melt is
cooled, viscosity increases to such an extent (ca. 1011 -1013 poise) that the time scale of
the experiment becomes similar to or longer than the molecular relaxation times. The
temperature dependence of the coefficient of thermal expansion, elastic modulus,
01 specific heat, dielectric constant, chemical shift linewidth, difïusivity, etc. defines the
0
ch glass transition temperature, but (it is argued) the change in these parameters is due to
0.
1 the frequency of molecular motion with respect to the measurement frequency or time,
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8- not due to the existence of a thermodynamic second order transition temperature.
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9 DiMarzio suggests in Chapter 2 that there is an intimate connection between kinetic
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k- and equilibrium quantities and argues for a thermodynamic transition on the basis of
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21/ theory and experiment, as do Bohn and Krtiger in Chapter 5. For the purposes of this
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oi: 1 by the observation that the large-scale cooperative rearrangements of the molecules
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201Dat configurational states on an energy landscape is greatly reduced in the glass as
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"personality", and knowledge of this energy landscape gives information regarding the
solidification history, the structure of the polymer glass, the population of
configurational states available and the energy necessary for configurational
rearrangements which lead to relaxations in the glassy state. Angell discusses in
Chapter 3 the factors that affect the energy landscape placing emphasis on the α-β
bifurcation temperature (or the temperature at which the β relaxation diverges from the
main α relaxation). In this case the α relaxation is used to describe the large-scale
cooperative rearrangements of the molecules in the region of the glass transition whilst
the β relaxation is used to describe slower segmental or sub-T relaxations. The
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persistence of local-scale cooperative, as well as uncoupled segmental, motion of the
molecules in the glass is of interest from the polymer physics as well as applied
property points of view and will be explored further in this chapter as well as Chapters
8-12. It is thus important to be able to predict the energy landscape of a polymer
glass, or if this landscape is infinitely complicated, to be able to predict and measure
In Structure and Properties of Glassy Polymers; Tant, M., et al.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1999.
3
the main factors that reflect this landscape, namely the relaxation times for the
molecular motions.
Figure 1 shows an isobaric specific volume-temperature schematic for glassy,
liquid and crystalline states of a polymer. The theoretical 100% crystalline material
has a first order thermodynamic transition at T, which represents the melt
m
temperature. The first feature of interest for glassy polymers is the departure from
equilibrium on cooling. As the polymer is cooled below T, nonequilibrium properties
g
(in this case volume, but as shown in Chapter 13, enthalpy as well) are quenched in
and will relax to some quasi-equilibrium value with time. The quasi-equilibrium
glassy state is shown in Figure 1 as a dotted line extrapolated from the liquid. At
much lower temperatures the quasi-equilibrium dotted line displays a change of slope
associated with vanishing configurational entropy. As mentioned above, in addition to
1
0 volume and enthalpy changes observed on cooling through T, the entropy of the
0
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c polymer changes as indicated by a significant increase in relaxation times which
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71 signifies a decrease in the number of configurations available to the polymer system.
0
8- Kauzmann (16) originally noted the thermodynamic inconsistencies associated with
9
19 the extrapolation of equilibrium data far below T by calculating unrealistic quantities
bk- such as negative configurational entropy and gnegative free volume. Gibbs and
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org 9 | d Chapter 3 by Angell (75,18) further discuss Kauzmann's paradox and its resolution via
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OP through various relaxation regions labeled with Greek symbols. The largest change in

linear expansion coefficient occurs at T (the α relaxation). The schematic in Figure 1
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can be compared to experimental results for poly(methylmethacrylate) shown in
Figure 2 (21). Each relaxation can be attributed to a particular molecular
rearrangement in the glassy polymer and research to discover the molecular
mechanisms responsible for the sub-T relaxations in glassy polymers is ongoing.
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Cartoons in Figure 2 suggest the motions attributed to each relaxation in PMMA.
Chapter 10 by Pratt and Smith discusses assignment of sub-T dielectric relaxations in
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polycarbonate and polyester blends. The importance of these relaxational processes to
physical, mechanical and transport properties is discussed in a subsequent section of
this chapter entitled Links Between Sub-T Mobility and Macroscopic Properties. The
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sub-T mobility responsible for these relaxations reflects the energy landscape of the
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glass and as such, the activation energies for the relaxations and the distribution of
relaxation times can give information on the intersegmental motion that affects
macroscopic properties.
In Structure and Properties of Glassy Polymers; Tant, M., et al.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1999.
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Figure 2. Specific volume-temperature data for poly(methylmethacrylate).
(Adapted from ref. 21.)
In Structure and Properties of Glassy Polymers; Tant, M., et al.;
ACS Symposium Series; American Chemical Society: Washington, DC, 1999.