Colored Poly(vinyl chloride) by Femtosecond Laser Machining

Abstract

Colored poly(vinyl chloride) (PVC) was fabricated by femtosecond laser micromachining without the addition of chemical colorants, eliminating the concern of leaching dyes and pigments. We determined that the changes in surface chemistry and surface topography both contribute to the observed yellow, brown, and black color formation. X-ray photoelectron spectroscopy (XPS) on the machined samples showed that conjugated double bonds are liable for the yellow and brown colors, whereas the presence of oxidized carbon and surface topography contribute to the black color. Fourier transform infrared spectroscopy (FTIR) indicated that laser irradiation altered the material’s properties only near the surface, which left the bulk properties unaltered. Furthermore, chemical resistance tests showed that some of the samples were able to withstand the influence of aggressive chemicals and their color did not fade. Finally, we showed that the fabrication of colored PVC highly depends on its ablation energy threshold which is affected by the laser pulse duration and wavelength.