Degradation of Plastics in Simulated Landfill Conditions.

Quecholac-Piña Xochitl,Hernández-Berriel María Del Consuelo,Espinosa-Valdemar Rosa María,Vázquez-Morillas Alethia,Mañón-Salas María Del Consuelo

doi:10.3390/polym13071014

Abstract

Different degradable plastics have been promoted as a solution for the accumulation of waste in landfills and the natural environment; in Mexico, the most popular options are oxo-degradable, which degrade in a sequential abiotic–biotic process, and compostable plastics. In this research, high-density polyethylene, oxo-degradable high-density polyethylene, and certified compostable plastic were exposed to simulated landfill conditions in an 854-day-long experiment to assess their degradation. High-density polyethylene showed limited degradation, due mainly to surface erosion, evidenced by a 13% decrease in elongation at break. The pro-oxidant additive in the oxo-degradable plastic increased this loss of mechanical properties to 27%. However, both plastic films kept their physical integrity and high molecular weight by the end of the experiment, evidencing degradation but no biodegradation. While the compostable film fragmented, had a lower molecular weight at the end of the experiment, and decreased the presence of C=O bonds, this degradation took place remarkably slower than expected from a composting process. Results show that oxo-degradable and compostable plastics will not biodegrade readily in landfills. This fact should be known and understood for decision-makers to match the characteristics of the materials to the features of the waste management systems.

Highlights

Plastics emerged as a basic material for the functioning of the global society in the 20th century
High-density polyethylene (HDPE) containing the prooxidant additive d2w® and a conventional HDPE with the same gauge were used as examples of oxo-degradable and conventional plastic
The mixture was divided into three portions, and each one was amended with a specific type of plastic film: HDPE, oxo-degradable polyethylene (HDPEOXO), and ECOVIO®

Summary

Introduction

Plastics emerged as a basic material for the functioning of the global society in the 20th century. The plastic production has increased continuously since the 1950s, reaching 359 Mt in 2018 [1]. They are used in different sectors, such as communication, medicine, agriculture, and transportation, 36% of the global plastic production in 2015 was related to packaging [2], mainly in products with short useful lives, such as bags and bottles. As a result of the growing production and discard, plastic waste has become an issue of global concern, accounting for 12% of the waste produced worldwide [3]. While some of them focus on reducing the consumption and use of plastics, such as plastic bag bans, other interventions tackle the end-of-life impacts through recycling and energy recovery [5]. A significant proportion of plastics end up buried in landfills and on dumpsites

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