Page 157 - Handbook of Adhesives and Sealants

Chapter
4

Standard Test Methods

4.1 Introduction

The testing of adhesives and sealants is a complex subject because
there are many parameters that can affect the test result. Interactions
of the adhesive and adherend are often obscure. The joint design and
type of load strongly influence the final stress distribution. The par-
ameters by which the test is conducted, such as strain rate, temper-
ature, and environmental conditions, also have a strong impact on the
test results.
Although complex, testing is an extremely important subject since
one cannot reliably predict the strength of the adhesive bond based
solely on characteristics of the adhesive, substrate, and the joint de-
sign. To determine the strength of the joint, one must resort to testing.
Through testing the many factors that can affect the strength of the
joint can be measured. Sometimes it is difficult to separate the vari-
ables that control joint strength, but at least through testing, we have
a vehicle to provide a quantitative approximation. Standard tests,
such as ASTM tests, are very useful for comparing and determining
the consistency of materials and processes. They are less valuable in
accurately predicting the strength of specific production joints. Usu-
ally, prototype tests must be designed for this purpose.
In this chapter, standard test methods for both adhesives and seal-
ants will be described. Similar test methods are often applied to both
adhesives and sealants since adhesion is a major factor in both appli-
cations. This chapter will review fundamental tests that are used to
control the consistency of materials used in these processes. The more
common end-use tests and the effect of testing variables, such as ad-
hesive thickness and strain rate, will be reviewed. Where possible,
correlation of end-use test results and the fundamental properties of
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