Soiling of pure PVC studied by FTIR, optical microscopy, and AFM

The soiling of unplasticized PVC with solid and liquid oily agents was studied with tripalmitin, palmitic acid, and triolein as model compounds. Deposition was made by spin coating technique. Quantification of the soiling agent on the PVC surface was done by FTIR spectroscopy, by determining the area of the nu(C=O) vibrations as a function of the concentration of the coating solution. The C=O stretching was characteristic for each model compound. Optical microscopy in normal and polarized light and noncontact atomic force microscopy (AFM) were used to study the structure of the model compounds and their dispersion on the PVC surface. Noticeable differences in topography were seen in comparisons of the clean PVC surface with soiled surfaces. The three model compounds formed different structures on the PVC surface.