Effect of interfacial bonding on the strength of adhesion

Abstract

synopsisThe strength of adhesion has been determined experimentally for an elastomer layer coupled to a rigid substrate by interfacial chemical bonds of varying surface density. Sites for interfacial bonding were obtained by treating glass plates with mixtures of vinyland ethylsilanes in varying proportions. A layer of polybutadiene was then applied and cross-linked in situ by a free-radical process. Formation of interfacial bonds to vinyl groups (when present) on the glass substrate is inferred from the proportional increase in strength of adhesion under near-equilibrium conditions, i.e., at low rates of detachment and at high temperatures. A 35fold increase in strength was found for vinylsilane, relative to ethylsilane, in rough agreement with the relative magnitudes of the strengths of covalent and dispersion bonds. However, the absolute magnitudes were much greater than predicted, by a factor of about 25 in both cases. This is attributed to the polymeric character of the elastomer: many molecular bonds must be stressed in order to detach or rupture one.4 In agreement with this hypothesis, the strength of adhesion decreased with increasing crosslinking. Anomalously high adhesion was found with clean glass.It presumably reflects a specific bonding mechanism of unknown type.

The role of molecular diffusion in the adhesion of elastomers

“…6 It is clear that the mechanical strength of an adhesive joint depends upon both the intrinsic strength of the interface and upon the viscoelastic properties of the adhering materials (21,22). Thus, in order to clarify the role of interdiffused molecules upon the strength of adhesion, it has proved necessary to study the response over a wide range of test speeds and temperatures.…”

Effect of size of nonreinforcing fillers on mechanical properties of elastomers

“…These studies on model systems (Ahagon and Gent, 1975;Runge and Dreyfuss, 1979;Dreyfuss etal. 1981) have proven to be very helpful in elucidating the effect of chemical bonding on adhesion.…”

Effect of number of chemical bonds on the strength of adhesion between glass and polybutadiene

“…We believe the scatter is . Table 1 shows The comparison would be even better if dispersion and van der Waals forces are considered (3 ) . Furthermore, experimentally at any given time it is not possible to stress only one bond of a crosslinked network .…”

“…The specimen d i f f e r s from those used in earlier work (3)(4)(5) in t h a t the adhesive was applied to both sides of the slide instead of to one only in order to make mo re e f f i c i e n t use of the '4 C labelling, which was distributed over the entire surface of the slide . Previous work has shown that each laye r of the specimen is require d …”