What exactly happens – and what is left – when the bag degrades?
The system we are using is a two step process: initially there is a chemical process where oxygen attacks the carbon chains in the HDPE, turning long chains into smaller and smaller chains which now incorporate oxygen in their chemical make-up. At this point, the plastic has been turned into organic functional groups (ketones, carboxylic acids, alcohols etc) which attract water. These transformations (smaller chains and the presence of oxygen and water) create the conditions for a potential second stage: microbial digestion. If micro organisms are present (as they will be in compost or landfill) then these small fragments will be included in their tropic chain, as food. These fragments therefore decompose further into simple elements: carbon dioxide, water and biomass (biomass is just the organic waste of microbe cells). This process is similar to the degradation of lignin in wood.
