Plastic waste remains a critical environmental challenge,
with
14.5 million tons generated in 2018 alone, 85% of which ended up in
landfills in the US. A key contributor to this issue is the nonrecyclability
of multilayer laminations; when different materials are fused, they
cannot be easily separated for recycling, thereby exacerbating municipal
solid waste problems. This study explores an innovative approach by
laminating base layers of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) or stereocomplex-polylactic acid with a biodegradable
coating of poly(vinyl alcohol) and nanoclay to polylactic acid. Since
all the materials are biodegradable, the final structure is also anticipated
to be biodegradable in compost environments, opening an additional
regenerative end-of-life scenario. The effectiveness of these biodegradable
layers was assessed by measuring the moisture vapor transmission rate
(MVTR) and oxygen transmission rates (OTR), which ranged from 20 to
30 g/(m2·d) and 54 to 69 cc/(m2·d),
respectively. Through optimizing, theoretical rates were estimated
at an MVTR of 10 g/(m2·d) at 38° and 90% RH and
an OTR of 60 cc/(m2·d) at 23 °C and 50% RH, showcasing
low permeability for several biodegradable products. Additionally,
water barrier activation energy was measured across four selected
structures, ranging from 41 to 58 kJ/mol, indicating that the developed
material can potentially package several types of food products in
a biodegradable formata significant advancement from previous
compostable plastic structures and packaging industry capabilities.