Browsing by Author "Korpela, Heta"

One of the most common packaging materials for food is polymers. The properties offered by plastic packaging are good for food, but there is a general demand to reduce the usage of plastic. The demand for reduction is due to the fact that plastic is often made from fossil raw materials. In the case of foodstuffs, it is not possible to completely remove the plastic packaging material as this would result in faster food spoilage and thus greater food waste. The amount of plastic can be reduced by using it as part of the multilayer material. In multilayer materials, the most common raw material is cardboard, which is generated from renewable raw materials. In addition to plastic packaging made of virgin material, plastic materials made from recycled polymers may also be used in food packaging in future, provided that their safety conditions are met. The aim of the study was to investigate the effect of freezing temperatures and ultraviolet radiation (UV) on the properties and aging of recycled plastic. The research methods were divided into physical, barrier and chemical measurements. Samples were imaged using a scanning electron microscope. The hypothesis in the study was that freezing conditions and UV treatment both age the packaging material. UV radiation is expected to age samples more than freezing conditions. The study will focus on PET (polyethylene terephthalate) and LDPE (low density polyethylene) coated cardboards. The study partially answers to the hypothesis. Frost conditions were had weaker aging effect than UV radiation, as expected. On the other hand, recycled plastics cannot be said to be easier to age than virgin materials. Particularly between the different measurements, the materials did not differ clearly in their aging.