Degradation features of bioplastics-based disposable straws in soil and aerobic mineralization: Insight into final properties and chemical pathways.

Abstract

The transition to a sustainable economy has led industries to seek new raw materials for the production of renewable-based plastics. The present work shows the confirmation of formulation and initial degradation features in non-controlled soil of five types of straws including bio- and fossil-based polymers demonstrating that those based on starch could contain bio-based polymers; bio-based-polyethylene (PE) and -poly(propylene) (PP). Biodegradation percentage, structural, thermal, morphological and visual analysis are discussed indicating that after twelve weeks there is low weight loss percentage which is higher for cellulose, followed by starch/low density poly(ethylene) (LDPE) (S/LDPE), corn starch/poly(propylene) (S/PP), poly(lactic acid) (PLA) and PP. Selected avocado and corn-based straws (S/LDPE and S/PP) were subjected to controlled CO2 evolution test through ASTM D5338-15 essay to stablish the biodegradation percentage. Derived from CO2 evolution test of selected S/LDPE and –S/PP, it is established that the carbon present in the sample follows two possible routes; 1) Biomass growth, corroborated by the increase in colony-forming units in fungi and aerobic mesophilic bacteria, and 2) metabolization expressed in CO2 production. The S/LDPE straw presented higher biodegradability in both tests than S/PP. Insights of chemical pathways and final monitoring properties are discussed. These findings provide information to be used to support policies around the world to consider more sustainable materials that are not just bio-based materials but ensure their biodegradation into bioplastic products.