Thick elastomeric coating removal using tailored infrared- and infrared-sonication hybrid technology

We report an innovative, cost-effective, and eco-friendly coating removal technology that removes thick polyurethane-based elastomeric coatings without damaging the underlying metal or glass-polymer composite substrates. The developed technology eliminates the need for chemical- or media-based treatments, thus reducing environmental problems such as releasing toxic gases or suspended solid particles in the air. This was achieved using tailored infrared and infrared-ultrasonication treatments of the coated substrates that caused bond failure at the surface coat-substrate interface by selective absorption of IR and/or impinging of the topcoat with the ultrasonication technique. The degraded interfacial adhesion strength then allowed easy removal of the specialty coating with the application of a pull at a certain angle to the substrate-coating interface. The effect of different operating parameters such as time of irradiation, surface temperature, sonication power/intensity was investigated to determine the optimal conditions for coating removal. The treated and untreated coated samples were characterized by DSC, SEM, FTIR, peel-tester, embedded thermocouple/LABVIEW, and infrared thermography techniques. The energy analysis revealed that the fracture energy component was 4× lower on the treated sample than the untreated sample indicating reduced bond strength, which can be explained based on residual thermal stress generated due to the thermal coefficient mismatch and the interfacial cell dislocation. Also, coating from the treated sample could be removed 1.75× faster than from the untreated sample. Based on the cost analysis, the operation cost for this technology is meager compared to conventional and energy-intensive technologies such as laser ablation.