Biodegradable and\nTransparent Water and Oxygen Barrier\nMultilayer Film

Plastic waste remains a critical environmental challenge,\nwith\n14.5 million tons generated in 2018 alone, 85% of which ended up in\nlandfills in the US. A key contributor to this issue is the nonrecyclability\nof multilayer laminations; when different materials are fused, they\ncannot be easily separated for recycling, thereby exacerbating municipal\nsolid waste problems. This study explores an innovative approach by\nlaminating base layers of poly(3-hydroxybutyrate-<i>co</i>-3-hydroxyvalerate) or stereocomplex-polylactic acid with a biodegradable\ncoating of poly(vinyl alcohol) and nanoclay to polylactic acid. Since\nall the materials are biodegradable, the final structure is also anticipated\nto be biodegradable in compost environments, opening an additional\nregenerative end-of-life scenario. The effectiveness of these biodegradable\nlayers was assessed by measuring the moisture vapor transmission rate\n(MVTR) and oxygen transmission rates (OTR), which ranged from 20 to\n30 g/(m<sup>2</sup>·d) and 54 to 69 cc/(m<sup>2</sup>·d),\nrespectively. Through optimizing, theoretical rates were estimated\nat an MVTR of 10 g/(m<sup>2</sup>·d) at 38° and 90% RH and\nan OTR of 60 cc/(m<sup>2</sup>·d) at 23 °C and 50% RH, showcasing\nlow permeability for several biodegradable products. Additionally,\nwater barrier activation energy was measured across four selected\nstructures, ranging from 41 to 58 kJ/mol, indicating that the developed\nmaterial can potentially package several types of food products in\na biodegradable formata significant advancement from previous\ncompostable plastic structures and packaging industry capabilities.