Table Of ContentSTRUCTURE-PROPERTY
RELATIONSHIPS OF
POLYMERIC SOLIDS
POLYMER SCIENCE AND TECHNOLOGY
Editorial Board:
WIlliam J. Bailey, University of Maryland, College Park, Maryland
J. P. Berry, Rubber and Plastics Research Association of Great Britain,
Shawbury, Shrewsbury, England
A. T. DIBenedeHo, The University of Connecticut, Storrs, Connecticut
C. A. J. Hoeve, Texas A & M University, College Station, Texas
Yolchl Ishida, Osaka University, Toyonaka, Osaka, Japan
Frank E. Karasz, University of Massachusetts, Amherst, Massachusetts
Oslas Solomon, Franklin Institute, Philadelphia, Pennsylvania
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STRUCTURE-PROPERTY
RELATIONSHIPS OF
POLYMERIC SOLIDS
Edited by
Anne Hiltner
Department of Macromolecular Science
Case Western Reserve University
Cleveland, Ohio
PLENUM PRESS • NEW YORK AND LONDON
Library of Congress Cataloging in Publication Data
American Chemical Society. Meeting (55th: 1981: Atlanta, Ga.)
Structure-property relationships of polymeric solids.
(Polymer science and technology; v. 22)
"Proceedings of the 55th Meeting of the American Chemical Society, held in honor of
the Bordon Award recipient, Professor Eric Baer, during March 1981, In Atlanta,
Georgian-T.p. verso.
Includes bibliographical references and index.
1 . Polymers and polymerizatlon-Congresses. I. Hiltner, Anne. II. Beer, Eric. III. Title.
IV. Series.
TA455.P58A391981 620.1'92 83-16131
ISBN 978-1-4684-4615-9 ISBN 978-1-4684-4613-5 (aBook)
00110.1007/978-1-4684-4613-5
Proceedings of the 55th Meeting of the American Chemical SOCiety,
held in honor of the Bordon Award reCipient, Professor Eric Baer,
during March 1981, in Atlanta, Georgia
© 1983 Plenum Press, New York
Softcover reprint of the hardcover 1s t edition 1983
A Division of Plenum Publishing Corporation
233 Spring Street, New York, N.Y. 10013
All rights reserved
No part of this book may be reproduced, stored in a retrieval system, or transmitted
In any form or by any means, electronic, mechanical, photocopying, microfilming,
recording, or otherwise, without written permission from the Publisher
PREFACE
This book contains a collection of original research papers
which were presented in honor of the Bordon Award recipient,
Professor Eric Baer, on the occasion of the 55th Meeting of the
American Chemical Society (Atlanta, Georgia, March, 1981). The
contributors are present or former colleagues and students who
have worked with him in the Department of Macromolecular Science
at Case Institute of Technology of Case Western Reserve University.
Throughout his work, Eric Baer has attempted to find the relation
ships of solid state structure and hierarchy to the resultant pro
perties from which specific functions are derived. Although he
has studied many seemingly unrelated subjects, from irreversible de
formation, mechanics and yield processes in amorphous polymeric
solids to structural organization and mechanical function of ten
don, his unique goal has been to develop models from the real
structure that would allow a quantitative description of properties.
Today, this area of "microscience" is rapidly expanding as new and
sophisticated applications of polymeric materials with multifunc
tional properties are emerging from our understanding and control
of the solid state. The wide-ranging ideas and the original
ity of Professor Baer's contributions have stimulated many new
concepts which are now widely accepted in the field of high
polymers. The contributions to this volume represent many of the
areas which he has explored.
A. Hiltner
v
CONTENTS
1. Crazing in Thin Films of "Monodisperse" Polystyrene. . .. 1
A. Moreno and E. Baer
2. Thermoreversible Gelation of Crystallisable Polymers
and Its Relevance for Applications . . . . • • 25
A. Keller
3. Conformational Characterization of the Single Crystal
Surface. . . . . 59
Y.A. Chang and A. Hiltner
4. Substitution Reactions on Halogenated Polyethylene 75
Ian R. Harrison, Jacqueline S. Butler, and J.P. Runt
5. Structure Determination of Crosspolymerized Poly(l,ll-
Dodecadiyne) . . . . . . . . . . . . . . . 85
M. Thakur and Jerome B. Lando
6. Structure and Morphology of Nascent Polyethylenes
Obtained by TiC13 Heterogeneous Ziegler-Natta
Catalyst . . . . . . . . • .. ....• 95
A. Munoz-Escalona, C. Villamizar, and P. Frias
7. Crystal Transformation, Piezoelectricity, and Ferroelec
tric Polarization Reversal in Poly(Vinylidene
Fluoride). . . . ....•....•... 115
Kasumi Matsushige and Tetuo Takemura
8. Crystal Nucleation in Flowing Polymer Melts .......• 139
Mark S. Pucci and Stephen H. Carr
9. Flow-Induced Crystallization and Orientation from the
Melt . . . . . . . . . . . .. ...... 155
J.R. Collier, K. Lakshmanan, L. Ankrom, and
S.K. Upadhyayula
vii
viii CONTENTS
10. Hydrostatic Extrusion of Glass Reinforced and Unrein-
forced Celcon POM • . • . • • • • 175
J. Kastelic, A. Buckley, P. Hope, and I. Ward
11. The Interaction of Liquid Environments with Hard
Elastic High Impact Polystyrene ..
Kim Walton, Abdelsamie Moet, and Eric Baer
12. Transmission Electron Microscope Studies of Polymers
Stained with Ruthenium and Osmium Tetroxide. 205
J.S. Trent, P.R. Couchman, and J.I. Scheinbeim
13. The Time-Temperature-Transformation (TTT) State Diagram
and Its Role in Determining Structure/Property Re
lationships in Thermosetting Systems • . . . . •. 215
John K. Gillham
14. Network Development in Films Cast from Emulsions of
Polydimethylsiloxane 227
Daniel Graiver, John C. Saam, and Madhu Baile
15. The Effect of Microcrazing on Fatigue Crack Propaga-
tion in Polymers • . . • . . . • . . . • 235
A. Chudnovsky, A. Moet, I. Palley, and Eric Baer
16. Advances in Strength Prediction for Short-Fiber Rein-
forced Plastics. . • • . . . . . . . . . • • .. 247
J.L. Kardos
17. Thermally Stimulated Current of Solid Pullulan 255
K. Nishinari, D. Chatain, and C. Lacabanne
Index . . . • . • . . . • . • • • . • . . • . . • . . . . .. 269
CRAZING IN THIN FILMS OF "MONODISPERSE" POLYSTYRENE
A. Moreno and E. Baer
Department of Macromolecular Science
Case Institute of Technology
Case Western Reserve University
Cleveland, Ohio 44106
ABSTRACT
A technique to study the relationship between mechanical behav
ior and craze microstructure of thin films of narrow disperse poly
styrene is described. Films about 2-4 ~m thick were tested in a con
ventional tensile machine (Instron). Craze kinetics were observed
through an optical microscope equipped with a motor-driven camera.
In this way, a direct correlation was established between the mech
anical behavior and craze growth kinetics. Effects of molecular
weight, thermal history and strain rate on both mechanical behavior
and craze kinetics were studied, and their relationship was elucidat
ed. Statistical analysis revealed that the phenomenon of crazing is
quite complex and depends on several material and experimental vari
ables. The average distance between crazes was found to follow
Poisson distribution, thus confirming the random nature of this phe
nomenon. The macroscopic strain (elongation) of the material during
the entire deformation history was explained in terms of the number
of crazes per unit area, craze extension and the distribution of
crazes. On the basis of experimental results, a model is suggested
from which the elastic modulus of crazed material can be derived.
INTRODUCTION
Research into various aspects of the phenomenon of crazing has
played an important role in shaping our understanding of the fracture
behavior and the toughening mechanism of polymers. Recent results
offer important clues to the structural nature of the glassy phase
of the macromolecular chain. Since the publication of exclusive
2 A. MORENO AND E. BAER
reviews by Rabinowitz and Beardmore [1] and Kambour [2], researchers
have continued to seek specific knowledge of the relationship of the
mechanical behavior to the molecular structure of glassy polymers.
A recent publication [3] gives the mechanistic steps associated with
craze formation from localized cavitation to fibrillation through a
local plastic deformation. The significant role played by molecular
weight was clearly identified. Whereas void nucleation was not influ
enced by molecular weight, the stability of localized plastic deform
ation and subsequent fibrillation was strongly dependent on molecular
weight. Only polymers with molecular weights above the critical en
tanglement molecular weight [4] were found to exhibit stable craze
growth. This molecular weight requirement was subsequently confirmed
by Fellers and coworkers [5,6]. In the latter study it was suggested
that crazing is greatly diminished in polystyrene with a molecular
weight less than twice the critical entanglement. Tensile measure
ments in polystyrene [7,8] and fracture energy estimation in poly
methylmethacrylate [9] invoke similar conclusions. Nevertheless, a
systematic study relating craze growth to molecular weight is missing
from the published literature.
This paper describes results of a study of the effect of molecu
lar weight on craze growth and mechanical behavior; both were observed
simultaneously. The effects of rate of deformation and thermal
history are also considered.
EXPERIMENTAL
Materials
Samples of narrow molecular weight distribution atactic polysty
rene were used for the tensile experiments. The polymers were supplied
by the Pressure Chemical Company; molecular weights and molecular
weight distributions are listed in Table 1.
Preliminary experiments indicated that there is very little, if
any, difference in the mechan~cal behavior gr the corresponding craz
ing kinetics between 6.7 x 10 and 1.8 x 50 molecular ~eight polymers.
It was decided therefore, to use 1.0 x 10 and 1.8 x 10 molecular
weight polymers to investigate the effect of molecular weight. In
the rest of this discussion these two polymers will be referred to
as low molecular weight (LMW) and high molecular weight (BMW),
respectively. AS the end of the discussion, however, results obtain
ed from 6.7 x 10 molecular weight polymers will be briefly reviewed.
All of the experimental results were averaged over at least five runs.
In one experiment, test results from fifteen identical samples were
averaged.
CRAZING IN THIN FILMS OF "MONODISPERSE" POLYSTYRENE 3
Table 1. Holecular Height, Holecular vleight Distribution and Glass
Transition for Polystyrene Samples
Short Form Hol. Wt. Hol. Wt. Distr. Tg (oe)
UfW 1.0 x 105 1.06 99.0
"v 6.7 x 105 1.15 99.8
}!M1;v 1.8 x 106 1.33 99.9
Film Preparation
The films were cast by dipping clean glass slides in solutions
of polystyrene in xyleng. The sol~tions were 5%3 9% and 13% by
weight for the 1.8 x 10 , 6.7 x 10 and 1.0 x 10 molecular weight
polymers, respectively.
The solvent was evaporated in two steps: first, in air at room
temperature for about one hour; then overnight in a vacuum oven at
about 870e. This temperature is at least 100e lower than the glass
transition temperature for the three polymers, as shown in Table 1.
These temperatures were calculated by using an extension of the
Fox-Flory theory [10,11].
After annealing, the samples were either quenched in ice water
or slow cooled (about 100e/hr) under vacuum. The films were then
removed from the glass slides by flotation on the surface of a water
bath and dried on filter paper. The thickness of film specimens
prepared in this manner ranged from 2.5 to 3.5 ~m, as determined by
infrared spectroscopy [12].
Fig. 1 shows a comparison between the IR spectra of polystyrene
an~lxyle~e, the casting solvent. The lack of absorbance in the 1380
cm reg10n in the PS spectrum indicates complete solvent removal.
This is f~Ither supported by the imperceptibility of the sharp peak
at 800 cm in the PS spectrum.
Sample Preparation and Testing
Specimens with a diameter and gauge height of 2 cm were cut with
a specially designed template. Subsequently, samples were annealed
to remove any excessive edge effects caused by the cutting procedure.
The edges of annealed samples appeared smooth at 60x magnification.
A conventional Instron testing machine was used for the tensile
experiment. A 500 g load cell, for which the minimum full scale
range is 10 g, was required to measure the small loads inherent in
thin film work. The tensile stress-strain measurements were carried5
out at two different strain rates: 0.1% and 0.025% for the 1.0 x 10
