Co-Authors: Partha Pratim Sengupta, Michael D. Blanton, and James W. Rawlins
University of Southern Mississippi

The paint stripping efficacy of aggressive solvents is based on the cohesive and adhesive failure of coatings by swelling and bond breakage. In this research work we measure the effect of both methylene chloride (CH2Cl2) and methylene chloridephenol (CH2Cl2-Ph, 19:1 blend) as effective commercial epoxy-amine paint stripping solvents. Solvent efficiency was evaluated based on the glass transition temperature, crosslink density, and thermal expansion coefficients of cured coatings by Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA), and Thermo Mechanical Analysis (TMA). The effects of residual solvents in commercial epoxyamine coatings on stripping solvents CH2Cl2 and CH2Cl2-Ph were also determined. The effect of paint stripping solvent on adhesion of the epoxy amine coating on pretreated aluminum alloy 2024-T3 (AA2024-T3) was measured by determining the coating remaining after the paint stripping process by Attenuated Total Reflection (ATR) spectroscopy and a modified scrub machine test to quantify the number of cycles needed to remove the coating in the presence of paint stripping solvents. The results show a direct correlation between adhesion and solvent stripping effect of the coating on pretreated AA2024-T3. An in situ study of the paint stripping process of the coating on pretreated AA2024-T3 was also conducted by optical microscopy.