Femtosecond laser removal of antifouling paints on glass fibre reinforced plastic used in maritime industry

Abstract

In this work we investigated the use of ultrashort laser pulses to clean antifouling paint from samples of glass fibre reinforced polymer (GFRP), a composite material widely used in shipbuilding. Samples were prepared with two types of paint, self-polishing and hard matrix, according to the scheme used in the hipyard. The paints and the GFRP substrate were characterised by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) with energy dispersive X-ray spectrometry (EDS). The effectiveness of the cleaning treatment and the effects on the substrate were evaluated by optical microscopy, interferometric microscopy, SEM-EDS and FTIR spectroscopy. The results indicate that satisfactory cleaning was achieved with controlled removal of unwanted layers without damaging or chemically altering the polymer bulk. The surfaces were also evaluated by SEM and interferometric microscopy to characterise morphological changes, and their wettability was characterised by contact angle measurements. In addition, the results were compared with those obtained by the conventional mechanical method (paint scraping and sanding). A roughening of the laser cleaned surfaces was observed compared to untreated surfaces as well as compared to mechanically cleaned surfaces. Laser treatment caused a decrease in wettability; sanded surfaces showed comparable behaviour. This study demonstrates the potential of femtosecond lasers for safe and effective cleaning of GFRP substrates in a more environmentally friendly manner