Oxodegradable plastics: degradation, environmental impact and recycling

Abstract

This paper summarises the results of a study to assess the environmental impact of oxo-degradable plastics. These plastics are mainly based on polyethylene and contain additives that cause the plastic to undergo oxidative degradation by a process accelerated by light and/or heat. The approach used in the study has been to review the published research on oxo-degradable plastics, assess other literature available in the public domain, and also to engage with stakeholders throughout the life cycle of the product. The main purpose of the study was to assess what happens at the end of life of the plastics and whether this has a beneficial effect. The study concluded that incorporating additives into petroleum-based plastics to accelerate their degradation does not improve their environmental impact and potentially gives rise to certain negative effects. In particular there is concern that these plastics are neither suitable for conventional recycling methods, due to the presence of degradation accelerators, nor suitable for composting, due to the lack of biodegradability. There is also concern about the fate of oxo-degradable plastic fragments in the environment.

Investigating the degradability of polyethylene using starch, oxo‐material, and polylactic acid under the different environmental conditions

“…As a result, the study on environmentally friendly plastics became the interest of many research groups. [16][17][18] From the literature, it is suggested that the oxo-materials could reduce the degradability time of the plastics to 2-5 years in the United Kingdom. In the first method, plastics are made from renewable feedstocks such as polyhydroxyalkanoates and polylactic acid (PLA).…”

“…[8][9][10] There are two main strategies to develop biodegradable plastics. 18 The mechanism of degradation of polyethylene was reported by Thomas et al 18 In the first step, polyethylene is oxidized as below: Using this strategy can reduce greenhouse gas emissions.…”

“…18 There are many studies in the oxo-material degradability properties. Fe3 + + RO: + OH − Fe3 + + ROOH !…”

“…The mechanism of oxo-biodegradability can be explained by the reaction of the oxygen with the free radicals, which were produced by the cracking of polyethylene chain. [16][17][18] From the literature, it is suggested that the oxo-materials could reduce the degradability time of the plastics to 2-5 years in the United Kingdom. 18 The mechanism of degradation of polyethylene was reported by Thomas et al 18 In the first step, polyethylene is oxidized as below:…”

Effect of the Prodegradant-Additive Plastics Incorporated on the Polyethylene Recycling

“…The imminent degradation, as a result of the action of oxo-degradable additives, has made these types of material nonrecyclable [20]. Also, the lifespan of the oxo-degradable polyolefins depends on polymeric chains (unsaturated or branched) and their susceptibility to capture oxygen.…”