On-line NIR Chemical Imaging of Functional Polymeric Films for the Food Industry

Multi-layer oxygen barrier polymeric films are used in the food packaging industry to ensure food conservation over a certain shelf-life. Different types of barrier films are currently developed for molding on the external surface of plastic containers to create an oxygen seal. The performance of the containers related to shelf-life conservation depends upon 1) the quality of the barrier film itself which is mainly determined by the presence of the barrier layer, the homogeneous dispersion of the barrier component, and the absence of defects (e.g. holes, scratches, etc.) and 2) how well the film covers the containers (seal quality). Therefore, both the film alone and the film-container assembly need to be inspected before use for food packaging. Quality control cannot rely solely on lab characterization due to the high production speeds and the destructive nature of the tests which implies that a very small amount of films and containers can be verified. Preliminary work performed in our hyperspectral imaging lab has shown that NIR chemical imaging is a promising approach for film and container inspection.

Objectives: Develop a rapid and non-destructive system for inspecting multi-layer oxygen barrier polymeric films and film-container assembly.

Methodology: A large number of films produced under different conditions (i.e. formulations, process conditions) and film-container assemblies will be available for this PhD project. These will be supplied by our pilot plant polymer processing facility and also from commercial producers. The film samples will be characterized for mechanical and physical properties, as well as oxygen transfer rate using equipment located at Laval U. and outside materials development centers. The PhD project will involve the following steps: 1) scanning the film samples using NIR chemical imaging instruments, 2) analyzing the hyperspectral images using Multivariate Latent Variable (chemometrics) methods, 3) building models between the image features and the film properties, and 4) developing a real-time film inspection strategy aimed at detecting and identifying various types of defects. Application of the imaging system (or a simplified version) on film-container assemblies will also be investigated. Alternative inspection methods such as UV and visible imaging spectroscopy, fluorescence, and IR thermal imaging may also be considered. These instruments are already available in our imaging lab. Close collaboration with commercial producers will be maintained throughout the project.