Page 182 - Handbook of Adhesives and Sealants
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152 Chapter Four
Figure 4.6 Common types of adhesive peel tests: (left) floating roller peel, (center) climb-
ing drum peel, (right) t-peel. 6
and condition of the test. In preparing the samples, care must be taken
to produce void-free laminated bond-lines. A typical load curve for the
T-peel test is shown in Fig. 4.7. Peel strength is taken as the average
value of the center portion of the curve, usually over at least a 5 in.
length of crosshead travel.
The rate of peel loading is more important than in lap-shear loading,
and should be known and controlled as closely as possible. The rate
at which the load is applied is usually specified in the ASTM test
procedure. Adhesive thickness has a significant effect on peel-strength
values as does the angle of peeling. The relative effects of these pa-
rameters are also dependent on the elasticity of the adhesives.
Figure 4.8 shows the effect of peel speed and angle on the strength
of an epoxy adhesive. With elastomeric adhesives, thicker bond-lines
Figure 4.7 Peel test record. 4
