Roberts Plastics Ltd.

Degradable Explained

Oxo-degradable: An additive introduced in the extrusion process of the polyethylene breaks down the long hydro-carbon bonds of the plastic reducing the overall strength and eventually providing a nutrient source for microbes. These microbes eat the broken down molecules reducing what was once plastic to water, carbon dioxide and reusable biomass. This process requires oxygen and will not degrade in anaerobic conditions.

Biodegradable: The degradation of these plastics is a result of microorganisms present in the natural environment. Typically these plastics are starch based (usually corn) manufactured into poly lactic acid (PLA). Strength is compromised and the plastics are expensive to manufacture. These bags will degrade in conditions with little to no oxygen which results in methane gas emission (a gas 20 times more harmful to the environment than carbon dioxide) and leaves behind no useful biomass.

Compostable: Degradable bags that break down in a time frame comparable to known organics such as leaves and grass can be classified as compostable. Standards for these bags are defined in ASTM-6400. These conditions mandate a period of rapid degradation which can be achieved both with PLA and oxo-biodegradable plastics.