Development of environmentally composite food films from polyethylene, starch and polylactic acid polymer mixtures

The production of petroleum-derived plastics worldwide has regularly exceeded 400 million tonnes per year. The fact that most of the plastics produced cannot be recycled causes waste to accumulate and environmental pollution to increase. For this reason, the production and use of biodegradable plastics from an environmentally friendly perspective is gaining importance. However, biodegradable polymers cannot fully replace petroleum-based synthetic polymers due to their low production quantities, high costs and weaknesses in their mechanical properties. Until the full transition to biodegradable polymers is achieved, the use of materials produced by mixing petroleum derivatives and natural polymers at certain ratios is considered more feasible today and research in this field comes to the fore. With the studies carried out, the use of composite biodegradable contents as packaging materials in the packaging sector is encouraged in the preparation and development of new packaging materials from renewable resources. As biobased polymers, plant-based polymers, polysaccharides (such as starch, cellulose, chitosan), proteins (such as zein, gelatin) and oils and PLA, PHA and resins produced from natural sources can be used. In this thesis, it is aimed to investigate the possibilities of using films produced from low-density polyethylene, a petroleum-derived polymer, and polylactic acid and thermoplastic starch mixtures, which are biodegradable polymers, as food packaging films with increased environmental and biodegradability properties. Mechanical, optical, barrier, behavior against water, migration, structure and thermal analyses were performed in the films. The thicknesses of the films were found between 0.06-1.07 mm, the tensile strength between 6.29-13.96 MPa, elongation at break between 2.4-610.6%, puncture force between 4.0-46.4 N, puncture elongation between 1.2-12.4 mm. Among the barrier properties, water vapour permeability was determined between 0.05-0.15 g/m2.h.kPa. The color difference from the optical properties was determined between 0.70-29.67. In terms of food contact compatibility, as a result of migration analyses (as mg/dm²), GB-A 2.6-41.8, GB-B 1.6-57.4, GB-D21 LOD-27.8 and GB-D22 LOD-31.20 were found. From the behavioural analysis of the films against water; water solubility values were found between 0-3.41%, moisture value between 0-7.99% and water holding capacity values between 0-7.06%. In terms of thermal analyses by DSC and structure determination analyses by FTIR, the characteristic properties of each polymer in the composition were also determined in the films. Keywords: Plastic, Polyethylene, Polylactic Acid, Starch, Biodegradable, Food Packaging.