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What Are Compostable Plastics?

bioplastic-products.jpgMany of our products are bioplastics, which are a new generation of plastics that are biodegradable and compostable, unlike standard plastic which does not degrade.

Our bioplastics are derived generally from renewable raw materials like starch (e.g. corn, bamboo pulp, potato, tapioca etc), cellulose, soy protein, lactic acid etc. They are not hazardous/toxic in production and decompose back into carbon dioxide, water, biomass etc. when composted.

Our bioplastics products meet the required compostability standards to present them as compostable products. These standards include Australian Standard 4736:2006, ASTM D6400 and D6868 (America's equivalent), EN13432 (the European equivalent) and ISO 14855 (the International equivalent).

So how does compostable and biodegradable plastic differ from other plastic?

According to the American Society for Testing and Measurement (ASTM-D6400 & ASTM-D6868) Compostable Plastic is that which is capable of undergoing biological decomposition in a compost site so that the plastic is not visually distinguishable and breaks down to carbon dioxide, water, inorganic compounds, and biomass, at a rate consistent with known compostable materials (e.g. cellulose), and leaves no toxic residue.”

According to Australian Standard 4736:2006, Compostable Plastic must meet the following three criteria:

  • Biodegradability – requires 90% (60% in America) conversion of carbon into carbon dioxide within 180 days for resins made from single polymer and 90% conversion of carbon into carbon dioxide for co-polymers or polymer mixes;
  • Disintegration – requires less than 10% of the plastic remains on a 2mm screen within 120 days;
  • Eco-Toxicity – is measured by testing the concentrations of heavy metals to ensure that they are below the limits set by the standards and by testing plant growth by mixing the compost with soil in different concentrations and comparing plant growth in test and controlled compost.

Biodegradable Plastic (Bioplastic) differs from compostable plastic. It is plastic which will degrade from the action of naturally occurring micro-organisms (e.g., bacteria, fungi) over a period of time. However with biodegradable plastic there is no requirement for “eco-toxicity” and no time requirement for the biodegradation of biodegradable plastic.

Summary

The rate of biodegration for different plastics is dependent upon the composition and thickness of the material as well as composting conditions. Commercial composting facilities grind the materials, turn over the piles and reach high temperatures, thus reducing the amount of time it takes to compost and, is thus, the recommended method for composting our products. Home composting rates are slower and can vary, depending on how frequently the pile is turned over, the moisture and material content and the temperature.

(Sources: www.astm.org, www.worldcentric.org and www.ecoscientific.com.au)