Degradation of Plastics at Sea

Degradation implies loss of useful properties following chemical changes in plastic materials. In the marine environment only two major influences are likely to bring about these change over practical time scales solar radiation and slow 

Kber Density (g/cm ) Wet Breaking Strength (% of dry strength) Weight in Water (% of dry weight) Percent Moisture Gain at 65% Humidity Shrinkage in Water at 100°C (%) 

The degradation of plastics in air and in seawater shows some key similarities as well as differences  

The chemical pathways involved in photooxidative or other photodegradation of polymers in air and in the marine aqueous environment are essentially similar. 

Unlike plastics exposed on land, those exposed floating on the sea s surface do not suffer from heat buildup due to absorption of infrared radiation in sunlight, as the ocean acts as an efficient heat sink. As a result bulk temperatures of these materials remain much lower than those concurrently expected with on land exposure at the same location. (With on-land exposures, for instance, it is possible for dark-colored plastics to have a surface temperature that is higher by as much as 30°C compared to the ambient air.) This will significantly slow rates of degradation at sea. 

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