Potato peels as biobased fillers for poly butylene succinate composites: the role of PLA-based compatibilizing agents towards new-generation food packaging materials

The combination of potato peels (PoPs) with polybutylene succinate (PBS) was investigated, aiming at fully biobased and potentially biodegradable packaging materials. Being mainly constituted of polysaccharides, protein and lignin, PoPs are highly polar and that may negatively affect the compatibility with the more apolar PBS. The compounding of PoPs with PBS (2:3 weight ratio) was tested at first using glycerol as low molecular weight plasticizer. Extruded films showed limited stability with time due to phase separation phenomena, resulting in a loss of mechanical stress upon aging. A polylactic acid (PLA) based compatibilizing agent has been synthesized, starting from L-lactide combined with starch and gluten to simulate the carbohydrate and protein fractions of PoPs, in a 70:30 ratio. The compatibilizing agent has been tested in different percentages in PBS-PoPs-glycerol compounds ranging between 0.5 and 2 wt%. Its effectiveness was demonstrated up to 42 days for films stored under controlled climatic conditions, showing constant tensile strength for the whole aging duration as opposed to the non-compatibilized samples. The synthetic approach adopted for the synthesis of the compatibilizing agent represents a versatile strategy to improve the stability of polyester based compounds with biobased fillers.