Surface properties and antibacterial characteristics of polyurethane modified by corona discharge for food processing industry

Thermal properties and durability make polyurethane (PU) ideal for conveyor belts in food processing industry. On the other hand, its susceptibility to adhesion of pathogens subjects him to surface treatment techniques. In this study, substrates of PU were exposed to corona discharge using air as treatment gas. The process parameters, such as treatment time and nozzle-substrate distance, and the microbicidal effects of the polymer surfaces against Staphylococcus aureus and Escherichia coli were examined. Changes in surface hydrophobicity occurred at short treatment times due to the introduction of polar groups, as proofed by X-ray Photoelectron Spectroscopy (XPS), while the surface morphology suffered minor changes as revealed by Scanning Electron Microscopy (SEM) imaging. Moreover, the hydrophilicity of plasma treated PU was minimal affected by the variation of nozzle-substrate distance, as long as the discharge was in contact with the polymer surface. The hydrophilic surfaces developed a very good resistance to bacteria adherence in few hours after incubation.