Abstract :
The JKR contact theory is employed to study the adhesion phenomena between two solid materials in intimate contact. The elastic contact
modulus and the work of adhesion of solid materials are obtained during adhesion tests by utilizing a micro force-deflection measuring apparatus.
Six of the plastic materials, including polyethylene polyoxymethlene (POM), polyamide (PA), terephthalate (PET), polyvinyl chloride (PVC),
polypropylene (PP), and ultra-high molecular weight polyethylene (UHMWPE) are used to evaluate the adhesion effect implied by the JKR theory.
Comparison is made between surface energy obtained from the adhesion tests with that by a dynamic contact angle analyser.
Results show that the load/deflection data in the loading phase are in good agreement with the predictions of JKR equation, and the experimental
data of unloading phase deviate significantly from the JKR theory. The phenomena of adhesion hysteresis in loading tests are responsible for these
results due to the effects of molecular reconstruction on solid surfaces in contact. The work of adhesions, and hence surface energies of plastic
materials, calculated by the best fitting of JKR equation with the experimental data in the loading phase, agree satisfactorily in a comparable
manner with that obtained using the contact angle analyser
