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

Interfacial forces responsible for the adhesion of a coating are influenced by the nature and magnitude of the interactions between the coating and th e substrate, When stresses are applied, these interactions may be altered, resulting in potential energy changes within the neighboring layers of macr omolecules 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 interaction s in polymer bilayer systems under elongational deformations and changes in potential energy, leading to determination of the work Of adhesion (W-A). This research expands the scope of previous findings and provides a relatio nship between the C-H stretching vibrational energy changes for acrylic/pol yethylene (ACR/PE), epoxy/polyethylene (EP/PE), acrylic/polypropylene (ACR/ PP), and epoxy/polypropylene (EP/PP) bilayer systems and the interfacial fo rces responsible for adhesion. Using the vibrational energies of the C-H st retching 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 W A and the glass transition temperature (T-g) of the top coating.