Adhesion in Cellulosic and Wood-Based Composites

254 Pages·1981·7.76 MB·English

by  S. Chow (auth.), John F. Oliver (eds.)

ADHESION IN
CELLULOSIC AND
WOOD-BASED COMPOSITES
NATO CONFERENCE SERIES
I Ecology
11 Systems Scienee
111 Human Factors
IV Marine Seien ces
V Air-Sea Interactions
VI Materials Science
VI MATERIALS SCIENCE
Va/ume 1 Molecular Metals
Edited by William E. Hatfield
Va/ume 2 Materials for Advanced Batteries
Edited by D. W. Murphy. J. Broadhead. and B. C. H. Steele
Va/ume 3 Adhesion in Cellulosic and Wood-Based Composites
Edited by John F. Oliver
Va/ume 4 Adhesion Problems in the Recycling of Concrete
Edited by Pieter C. Kreijger
ADHESION IN
CELLULOSIC AND
WOOD-BASED COMPOSITES
Edited by
John F. Oliver
Xerox Research Centre of Canada
Mississauga, Ontario, Canada
Published in cooperation with NATO Scientific Affairs Division
PLENUM PRESS· NEW YORK AND LONDON
Library of Congress Cataloging in Publication Data
Main entry under title:
Adhesion in cellulosic and wood-based composites.
(NATO conference series. VI, Materials science; v. 3)
"Proceedings of a conference on adhesion in cellulosic and wood-based com
posites sponsored by the NATO Science Committee (Materials Science Panel) and
held May 12-15, 1980, at Oueen's University, Kingston, Ontario."
Bibliography: p.
Includes index.
1. Composite materials-Congresses. 2. Adhesion-Congresses. 3. Cellulose
-Congresses. 4. Wood-Congresses. I. Oliver, John F. 11. NATO Science Com
mittee. Materials Science Panel. 111. Series.
TA418.9.C6A266 620.1'292 81·11983
ISBN 978-1-4684-8985-9 ISBN 978-1-4684-8983-5 (eBook) AACR2
00110.1007/978-1-4684-8983-5
Proceedings of a Conference on Adhesion in Cellulosic and
Wood-Based Composites sponsored by the NATO Science
Committee (Materials Science Panel) and held May 12-15,1980,
at Oueen's University, Kingston, Ontario, Canada
© 1981 Plenum Press, New York
Softcover reprint of the hardcover 1s t edition 1 981
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 trom the publisher
CONTENTS
Introduction 1
S. Chow
PLENARY SESSION I: COMPONENTS
Molecular and Cell Wall Structure of Wood 7
Richard E. Mark
Structural Wood Adhesives - Today and Tomorrow 53
Roland E. Kreibich
The Forests as a Source of Natural Adhesives . . . . . . .. 67
P.R. Steiner
PLENARY SESSION 11: ADHESION AND COMPOSITES
Adhesion and Adhesives: Interactians at Interfaces . . . 91
H. Schonhorn
Evaluation of Fiber Adhesion in Camposites 113
A. T. DiBenedetto
Bonding in Wood Composites 127
J.D. We110ns
PLENARY SESSION 111: CRITICAL PROPERTIES
AND THEIR DETERMINAT ION
Problems Encountered with Conventional
Fibre-Reinforced Camposites 149
Robert F. Landel
v
vi CONTENTS
Wood Composites . . . . 167
Robert H. Gi11espie
Time Dependent Properties 191
Rona1d G. Pearson
WORKSHOP SESSIONS
Workshop I - Morpho1oy and Mechanica1 Properties 213
Workshop II Surface and Interface 225
Workshop III - Durability . 233
Workshop IV - Fabrication, App1ications and Economics 239
Summary of Conference 247
B. Ranby
List of Participants 255
Index . . . . . . . . 259
INTRODUCTION
Cellulose is a versatile and renewable natural resource which
has attracted increasing attention in the last decade, expecially
after the energy crisis of 1973. Apart from its extensive use as
asolid product, wood is the most important source of cellulose
fibres for papermaking and is also widely used as a source of
energy. The form and availability ot· the forest provides a great
opportunity for technological improvement and innovation in the
future to satisfy the foreseeable increasing demand for wood
based products. For example, North American sawmills and plywood
mills presently recover only about 45 to 55% of logged wood while
the remainder is disposed as waste, if it is not used in pulp
manufacturing. In addition, top and branch wood, and logs from
non-commercial species which are presently not recovered from the
logging sites could provide an abundant and relatively
inexpensive resource for the manufacture of composite products.
Other valuable potential sour ces of cellulosic materials are
waste paper and agricultural waste.
A composite is the consolidation of two polymerie materials
such that one of the components acts as the adhesive binder while
the other forms the substrate matrix. In some cases, the matrix
and the adhesive may be the same materials. To maximize the
adhesion potential of the composite, the properties of the
substrate which can enhance, hinder or complicate the development
of optimum adhesion should be thoroughly explored and identified.
In cellulosic and wood-based composites, the role of the matrix
and the interface and component compatibility are of major
importance.
Recent research interest into the use of natural products such
as lignin, bark and foliage for adhesives, while achieving some
degree of technical success, has also generated controversy over
product durability and economy. The research and application of
natural product adhesives needs further development and thought,
especially in terms of availability, variability and potential
bond durability. Moreover, the role of synthetic resins (both
thermosetting and thermoplastic) in wood and cellulosic
composites should not be overlooked and suggestions to increase
their efficiency and diversity for enhancing composite properties
are required.
2 S.CHOW
The rheology of composite-product formation using different
substrates presents an exciting challenge, and the morphology and
mechanical properties of the multitude of wood composite products
now in use require additional study. Furthermore the performance
requirements of any new composite product needs more thorough
examination on a scientific basis in order to minimize the time
involved in establishing standards or specifications for product
acceptance.
There may be a need for a more liberal classification of the
adhesion forces in composite products, emphasizing the adhesive
used and the durability required in the end-product. In this
way, different categories of composites can be defined. Finally,
there should be more emphasis on the economic significance of
research results.
To encourage strategie basic research on the problems of
formulating cellulosic or wood-based composites, the NATO Science
Committee has sponsored this conference with the following
objectives:
1. Identify the scientific factors which:
a. Limit the more extensive use of low-cost cellulosic
materials in composites.
b. Restriet the wider use of cellulosic or wood-based
composites.
2, Determine the extent of existing knowledge on the
subject.
3. Identify the most pertinent problems that restriet the
development of suitable composites.
4. Suggest feasible research approaches to solve the
problems identified.
Successful formulation of composite products depends upon
overcoming problems such as the influence of moisture,
unfavourable chemical interactions of adhesive and matrix,
morphology of components, stability under ambient and varying
conditions, economics, etc. Because of the need to focus on and
facilitate discussion of these various factors, four groups were
organized to deal with the following specific areas:
Surface and Interface;
Morphology and Mechanical Properties;
Durability; and
Fabrication, Applications and Economics.
INTRODUCTION 3
It is hoped that the outcome of this conference will stimulate
the academic and industrial sectors to undertake more research
aimed at conserving scarce resources and encouraging greater use
of products made from more abundant materials such as wood.
S. Chow
Chairman, Program Committee
PLENARY SESSION I
COMPONENTS