7. Chemical Features of Food Packaging Materials

Chemistry is not only important in the production of packaging materials. Important reactions may take place or must occur during practical uses, when packages are filled with food and beverages and, after their use, addressed to recycling processes. For various reasons, these chemical changes can be very important; as a result, the most relevant ones of these modifications—corrosion, cracking, fractures, weathering, etc.—should be shortly discussed. Corrosion is usually referred to metals and, more rarely, to concrete, polymers and glasses. This complex phenomenon depends on different variables. Also, biodegradation and compostability have to be discussed when speaking of food packaging materials. Chemical resistance can be indirectly described in terms of stability to oxidation, resistance to corrosion and other performances. In addition, peculiar abuse tests are available when speaking of the resistance of materials under the combined effects of a stress and aggressive environmental. Consequently, modifications of weight, dimensions, mechanical properties and visual appearance are evaluated in order to express a rate of chemical resistance.