Rheo-photoacoustic (RPA) FT-IR spectroscopic studies of the adhesion of thermosets to polyolefins

Abstract

Interfacial forces responsible for the adhesion of a coating are influenced by the nature and magnitude of the interactions between the coating and the substrate. When stresses are applied, these interactions may be altered, resulting in potential energy changes within the neighboring layers of macromolecules forming an interfacial region. In this work, rheo-photoacoustic (RPA) Fourier transform infrared (FT-IR) analysis and previously developed theory were utilized in an attempt to correlate molecular-level interactions in polymer bilayer systems under elongational deformations and changes in potential energy, leading to determination of the work of adhesion (WA). This research expands the scope of previous findings and provides a relationship between the C-H stretching vibrational energy changes for acrylic/polyethylene (ACR/PE), epoxy/polyethylene (EP/PE), acrylic/polypropylene (ACR/PP), and epoxy/polypropylene (EP/PP) bilayer systems and the interfacial forces responsible for adhesion. Using the vibrational energies of the C-H stretching bands and their response to the elongational forces imposed at the interface, the WA values were determined for ACR/PE, EP/PE, EP/PP, and ACR/PP. These experiments also indicated that there is a correlation between WA and the glass transition temperature (Tg) of the top coating.