Biodegradation in Soil of Commercial Plastic Bags Labelled as “Biodegradable”

Abstract

Abstract Biodegradability of five commercial plastic bags labelled as “biodegradable” and two referent materials were studied by a soil test for three months. As a control experiment, for studying abiotic degradation under the climatic impact (ultraviolet, temperature, and moisture) a test in a weatherometer was performed. The changes in bag samples after tests were detected by optical microscopy, Fourier-transform infrared spectroscopy, differential scanning calorimetry, and tensile testing. It was found that all the bags may be separated into two groups: based on polyesters and based on polyolefins with oxo-additives. The second group demonstrated an ability to oxidation under UV radiation. The content of chalk filler provided a mass loss of the samples under soil and climatic tests due to its washing out. Three samples on the polyester basis filled with starch (the first group) had different compositions (polymers in the matrix were different). They showed a high biodegradability under soil conditions: mass loss was 14-21%, tensile strength decreased by more than 43%, and the surface was covered by the mycelium net. However, according to FTIR-spectroscopy, at the initial stage only starch filler biodegraded intensively, while polymer matrix was stable.

Keywords

• Commercial plastic bag
• polymer composite
• biodegradability
• soil test
• mass loss
• climatic oxidation
• accelerated weathering test
• polylactic acid
• polycaprolactone
• polybutylene adipate-co-terephthalate
• polyethylene
• cellophane
• microplastic
• pro-oxidant
• oxo-additive