Page 32 - Handbook of Adhesives and Sealants

2 Chapter One

1.2 Fundamentals of Adhesives and
Sealants
1.2.1 Importance of adhesives and
sealants
Adhesives and sealants surround us in nature and in our daily lives.
Substantial businesses exist to develop, manufacture, and market
these materials, and they are used within virtually every business and

industry. Applications abound from office ‘‘post-it notes ’’ to automo-
tive safety glass to footwear to aerospace structures to ‘‘no-lick’’ post-
age stamps. Many products that we take for granted could never exist
if it were not for adhesive bonding or sealing.
If someone could determine the total value added to our economy
by the relatively small amount of adhesives and sealants that are
used, the result would be staggering. Yet, with adhesives and sealants
all around us, with applications extending back to at least biblical
times, and with many examples of outstanding adhesion in nature
(e.g., barnacles and ice on roads), why are there so many failures when
we try to ‘‘engineer’’ the use of adhesives or sealants in practice? Why
does it seem as if we must resort to trial and error, if not a bit of luck
or magic? Examples of catastrophic disasters such as the 1986 Chal-
lenger space shuttle sealant problem and the 1988 Aloha Airlines 737
fuselage peeling apart in flight unfortunately also invade the history
of adhesives and sealants. Perhaps no other class of materials or tech-
nology is so essential yet so ripe for potential misadventure.
The adhesives and sealants industry is bolstered by thousands of
years of trial and error. This long history can be coupled with signif-
icant additions to the fundamental supporting sciences and with the
development of advanced materials and processes. Consequently, so-
ciety has generally progressed to a point where we actually trust not
only our fortunes but also our lives to these materials. The study of
adhesives and sealants and the sciences surrounding their application
has never been more important.

1.2.2 Definitions
As any science that has progressed over the centuries, the science that
supports adhesives and sealants has developed a jargon and language
of its own. Appendix A defines terms that are commonly used in these
industries. Important, basic terms necessary to develop a fundamental
understanding of how and why adhesives and sealants provide value
are given in this section.
Adhesives and sealants are often made of similar materials, and
they are sometimes used in similar applications. These materials have