Increased Performance of Thermoplastic Packaging Materials by Using a Mild Oxidizing Biobased Additive

Green additives such as prodegradants based on natural fatty acids and iron can improve the environmental profile of thermoplastic packaging materials. We present two studies in which this is demonstrated. In the first study, the addition of a green prodegradant to a 5-layer gas barrier laminate during processing provided a laminate with significantly reduced oxygen transmission due to the resulting oxygen-consuming degradation process. The result shows that material reduction and cost efficiency of packaging laminates can be combined, since 5-layer laminates with reduced oxygen barrier layer thickness and retained gas barrier properties are feasible. The products are interesting from an ecological and economic aspect. In the second study, the addition of a green prodegradant to several qualities of polypropylene that are used in packaging applications leads to materials that are readily degraded in accelerated weathering. The molecular weight of the modified polypropylenes after 830 hours of accelerated weathering is reduced from typically 80.000？g/mole to 1.500–2.500？g/mole. At such molecular weight levels, digestion by microorganisms is feasible. The mild prodegradant used in the study does not lead to degradation during processing. Thermoplastics containing such additives are therefore fully recyclable provided that they have not been exposed to a long period of weathering. 1. Introduction Thermoplastic packaging materials have in the past three decades faced an increasing demand to improve their environmental profile. As a consequence, significantly increased amounts of renewables have been used in packaging materials [1–8]. Additionally such materials often exhibit a green profile due to their biodegradability [9–11]. Reduced material consumption is also an important approach. Packaging materials with reduced wall thickness but preserved mechanical and/or gas barrier properties lead to reduced carbon footprint and combine environmental friendliness with cost efficiency. Another route to packaging materials with increased environmental profile is to establish effective recycling procedures. Littering should be significantly reduced if users are aware of the value of post-consumer packaging [12]. Conventional thermoplastic packaging materials can be turned into finally biodegradable materials by addition of prodegradant additives during processing into packaging products [13–15]. Prodegradants based on renewables such as fatty acid salts and environmentally friendly metals like iron are especially interesting. Thermoplastics containing such