The influence of high pressure treatment and thermal pasteurization on the surface of polymeric packaging films

Several common single layer films (PE-HD, PE-LD, PP-BO, PA6-BO and PET-BO) and multilayer (PS/PE, PP-BO/PEpeel and PET-BO/PE) films were treated by either high pressure (600 MPa) or temperature (80 °C/90 °C) to simulate a high pressure or thermal pasteurization process. The samples were tested by atomic force microscopy (AFM), profile method and surface energy measurements to obtain information about the influence of the treatments on the surface topography and surface energy of the samples and by differential scanning calorimetry and by tensile testing concerning material properties. As key figures arithmetic surface roughness (by AFM at Pulsed Force Mode and profile method), surface energy by surface energy measurement and adhesion between tip and surface by AFM were extracted. Results indicate an influence of both high-pressure processing and thermal-processing on the surface roughness of biaxial oriented polymer films as single layer films. Laminated biaxially oriented polymer films showed no changes regardless of which processing was performed. The surface energy was hardly affected by both of the treatments for any stretched, non-stretched, single or laminated films. Common single-layer and multilayer films were treated by either high pressure (600 MPa) or temperature (90 °C) to simulate a high pressure or thermal pasteurization process. The samples were tested by atomic force microscopy, profile method and surface energy measurements. Results indicate an influence of both high pressure processing and thermal processing on the surface roughness of biaxial oriented polymer films as single-layer films. Laminated biaxially oriented polymer films showed no changes regardless of which processing was performed.