Effects of Methylation and Neutralization of Carboxylated Poly(n-butyl acrylate) on the Interfacial and Bulk Contributions to Adhesion

Abstract

The relationship between the energy release rate (or adhesion energy) and the crack velocity has been measured for a variety of cross-linked elastomers based on carboxylated poly(n-butyl acrylate). Methylation of the carboxyl groups decreased adhesion energies to the glassy polymer substrates used in these experiments, and neutralization of the carboxyl groups increased the adhesion energy to these substrates. The primary effect of methylation or neutralization was to change the velocity dependence of the adhesion energy. These changes were consistent with changes in the measured relaxation times of un-cross-linked carboxylated, methylated and neutralized polymers. Effects on the critical energy release rate required for measurable crack motions were consistent with a contact charging mechanism, involving transfer of a proton for the carboxylated elastomers, and transfer of a sodium ion for the neutralized polymers.

The Effect of Chain Transfer Agent Level on Adhesive Performance and Peel Master‐Curves for Acrylic Pressure Sensitive Adhesives

“…The use of the WLF shift factor to provide relative molecular mobility information can be extended to cover a group of master-curves. [39] Focussing again on the cohesive failure regions of the AA4M-3 peel master-curves, the similarity of the slopes of the curves and the magnitudes of the peel adhesion values suggested that it may be possible to superpose them, thus construct a ''super'' master-curve. Indeed, Figure 7 shows that cohesive failure regions of the AA4M-3 copolymers can be made to overlay each other using horizontal shift factors (a C ).…”

Micromechanisms of Tack of Soft Adhesives Based on Styrenic Block Copolymers

“…[32,33,48] Although this increase in W with debonding rate has been commonly attributed to the (rate-dependent) dissipative properties of the adhesive, no mechanistic explanation has been provided and the underlying dissipation mechanisms can be very different for weak adhesion (mostly interfacial) or strong adhesion. [39] In our specific case the examination of Figure 9 and 10 shows that the superposition of the 40 : 60 and 50 : 50 data for W is rather fortuitous since neither the r max curves nor the e max curves can be superposed by a lateral shift but both effects exactly cancel each other.…”

“…In a relatively simple case involving weak adhesion, such as the propagation of a crack at the interface between a crosslinked elastomer and a flat rigid surface with no covalent bonds present, Equation (1) can be written as: [32,33] …”

“…In one specific case, t* was shown to be related to the terminal relaxation time of the uncrosslinked polymer [33] but a general relationship is still lacking.…”

Effects of thickness on the largely-deformed JKR (Johnson–Kendall–Roberts) test of soft elastic layers

“…The contact test based on JKR (Johnson-Kendall-Roberts) theory of adhesion (Johnson et al, 1971) has widely used in quantifying the work of adhesion between two soft elastic materials (Chaudhury and Whitesides, 1991;Ahn and Shull, 1998;Ghatak et al, 2000;Maugis and Barquins, 1978;Shull, 2002). This theory is applicable when the contact radius is small in comparison with the radius of the spheres.…”