Each year vast amounts of plastic are produced worldwide. When released to the environment, plastics accumulate, and plastic debris in the world's oceans is of particular environmental concern. More than 60% of all floating debris in the oceans is plastic and amounts are increasing each year. Plastic polymers in the marine environment are exposed to sunlight, oxidants and physical stress, and over time they weather and degrade. The degradation processes and products must be understood to detect and evaluate potential environmental hazards. Some attention has been drawn to additives and persistent organic pollutants that sorb to the plastic surface, but so far the chemicals generated by degradation of the plastic polymers themselves have not been well studied from an environmental perspective. In this paper we review available information about the degradation pathways and chemicals that are formed by degradation of the six plastic types that are most widely used in Europe. We extrapolate that information to likely pathways and possible degradation products under environmental conditions found on the oceans' surface. The potential degradation pathways and products depend on the polymer type. UV-radiation and oxygen are the most important factors that initiate degradation of polymers with a carbon-carbon backbone, leading to chain scission. Smaller polymer fragments formed by chain scission are more susceptible to biodegradation and therefore abiotic degradation is expected to precede biodegradation. When heteroatoms are present in the main chain of a polymer, degradation proceeds by photo-oxidation, hydrolysis, and biodegradation. Degradation of plastic polymers can lead to low molecular weight polymer fragments, like monomers and oligomers, and formation of new end groups, especially carboxylic acids.

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Pathways for degradation of plastic polymers floating in the marine environment

Mechanistic implications of plastic degradation

Polymer biodegradation: mechanisms and estimation techniques.

Use of recycled plastic in concrete: A review

(Nano)plastics in the environment ??? Sources, fates and effects

Recycling of bioplastics, their blends and biocomposites: A review

http://addiflex.net/english/PDF_Jakubovicz_ELSEVIER.pdf

Ignacy Jakubowicz

Papers

Recycling of bioplastics, their blends and biocomposites: A review

Evaluation of degradability of biodegradable polyethylene (PE)

Effects of accelerated and natural ageing on plasticized polyvinyl chloride (PVC)

Evaluation of the rate of abiotic degradation of biodegradable polyethylene in various environments

Influence of thermooxidative degradation on the in situ fate of polyethylene in temperate coastal waters.