Polyethylene in Food Packaging Technology. II. Effect of Anti-fog

Today the appearance of food packaging is very important because it has an advertising aspect and helps to sell the product better. In many cases, instead of relying on creating a beautiful color to give the appearance of a polymer package, the consumer wants the packaged product to be clearly visible in order to ensure its health and quality. Some polymers are highly transparent, however, when water molecules condense on the surface, small water droplets form. In transparent films and structures, water droplets act as a scatterer for incident light on the surface. This phenomenon, which is called fogging, makes the film appear opaque. Droplets are formed when the surface tension of the polymer is lower than the surface tension of water, and as a result, the water remains in the droplet form instead of forming a continuous layer. By increasing the critical surface tension of the polymer surface, anti-fog additives allow water molecules to spread on the surface and form a continuous layer of water that does not scatter light. Therefore, it does not interfere with the transparency of the film surface. In this article, the phenomenon of fogging, the production of polyethylene films with anti-fog capability, the types of anti-fog additives and the methods of mixing these materials with polymer have been reviewed, among others. Also, the methods of evaluating the anti-fog properties of polyethylene films were introduced.