Degradation behavior and environmental impacts of a hemp-containing "eco-friendly" compostable plastic in natural...

A field experiment was carried out to assess the degradation behavior and environmental impacts of hemp fiber-containing polymeric material labeled as "compostable plastic". The main question was: What happens if products made from this material are released into nature? To find the answer, small pieces of this composite material were exposed to sandy clay soil and river water for 2, 4, 8, 13, 18, 23, 28, and 33 weeks. After taking out, the samples were thoroughly analyzed using light and electron microscopy, thermogravimetry, differential thermal analysis, X-ray diffractometry, and Fourier-transform infrared spectroscopy. It was found that the material is fairly stable in both tested natural environments. It remained compact even after 33 weeks, almost without weight loss. Only about 10-15 % of its bioorganic content was decomposed during the long-term degradation. If products made from this material are left in the natural environment, they will cause long-term pollution, including the formation of microplastics. This "compostable" plastic also can not be composted because one of its components is degradation-resistant polypropylene. Thus, despite the manufacturer's declarations, the material is not a good choice for eco-friendly production. The results show that it is not always appropriate to dispose of materials labeled as "compostable plastics" or similar by putting them into a compost bin or just leaving them in nature. Our findings also highlight the need for an objective assessment of the environmental impacts of so-called "eco-friendly", "green", or "sustainable" products rather than their reckless promotion and consumption.