Numerical and experimental investigations for stripping mechanism of polyacrylate resin-based paint with a pulsed laser

In the paper, the underlying fundamental mechanisms of laser stripping of mixture paint of two polymers of polyacrylate resin and polyisocyanate resin are elucidated by molecular dynamics simulations, focusing on the mechanisms of breakage of bonds. In addition, experimental investigations of stripping mixture paint are conducted with a pulsed Nd:YAG laser in the air. The formed gas products and the residual paint surface during laser stripping are analyzed by GC/MS, FTIR, XPS, and RISE. Simulation results indicate that the breaking of the C–N bonds is the origin of the damage of polymers and facilitates the fracture process of polymers chain, leading to evaporation of individual atoms and single-chain excitation which is closely accompanied by breaking and rearrangement of the bonds. The main microscopic destruction mechanisms of polymers revealed by simulations include breakage of bonds, dissociation of a carbon backbone with the evaporation of individual atoms, and new components produced by rearrangement of bonds, which is very consistent with the experimental results. The structural damage of polymers has a significant influence on stimulating the stripping of the paint with laser loading. The resulting experimental and theoretical observations can provide a guideline and practical references for a better understanding of the mechanism of the paint removal. Graphical abstract