A combined imaging, microthermal and spectroscopic study of a multilayer packaging system

Abstract

The effectiveness of a packaging solution for the pharmaceutical and food industry is dependent on the integrity of the constituent layers and the interfaces formed between them. The deconvolution and analysis of the many intimate layers found in packaging is analytically challenging, requiring techniques capable of identifying sub-micron regions. Here we have characterized the chemical and physical nature of the layers in a multilayer packaging system along with the interfaces, using a combination of high-resolution atomic force microscopy (AFM), microthermal analysis using scanning thermal microscopy (SThM), and Fourier transform infrared (FT-IR) spectroscopy. In particular, localized thermal analysis is shown to reveal the thermal transitions of the individual layers, but it was found that care must be exercised when melting through one layer to the next, as this can result in overestimates of melting temperatures of the underlying layer due to excess power loss from the SThM probe to the already molten top layer surrounding the probe.

Atomic Force microscopy techniques to investigate activated food packaging materials

“…Also, it has been used to detect sub-micrometer features in LLDPE films loaded with natural antioxidants, i.e., alpha-tocopherol, quercetin, and their cyclodextrin inclusion complexes, which are studied for applications in food packaging to delay oxidative degradation of the polymer and the onset of oxidation of the packaged food during storage (Koontz et al, 2010). In addition to the study of food packaging surfaces, phase imaging can be used also to investigate cross-sections of food packaging materials, for example to highlight the different layers in multilayer packaging systems (Woodward et al, 2004).…”

Attenuated Total Internal Reflection Infrared Microscopy of Multilayer Plastic Packaging Foils

“…Analytical methods are needed to identify the origin of the individual layers of packaging materials, to determine their individual and total thickness, and to detect manufacturing defects. [5][6][7][8] Differential scanning calorimetry (DSC) is commonly used to determine the thermal properties of polymers. Melting properties and sometimes glass transition temperatures can be used to identify the different layers present in the foil.…”