World Centric® compostable plastic cups and containers are made from a bio-based plastic derived from renewable plants. Chemically, this material is known as PLA, or Poly Lactic Acid, which can be derived from a variety of plant-based starches.
Compostable Plastics are a new generation of plastics which are biodegradable through composting. They are derived generally from renewable raw materials like starch (e.g. corn, potato, tapioca etc), cellulose, soy protein, lactic acid etc., are not hazardous/toxic in production and decompose back into carbon dioxide, water, biomass etc. when composted. Some compostable plastics may not be derived from renewable materials, but instead derived made from petroleum or made by bacteria through a process of microbial fermentation.
Currently, there are a number of different compostable plastics resins available in the market and the number is growing every day. The most commonly used raw material for making the compostable plastics is corn starch, which is converted into a polymer with similar properties as normal plastic products. Other compostable resins are available made from potato starch, soybean protein, cellulose and as well from petroleum and petroleum by products. It is counter intuitive to think that compostable resins could be derived from petroleum, when all normal plastic products are derived from petroleum and are non compostable. However, there are certified compostable resins available in the market, derived from petroleum and the field of compostable plastics is constantly evolving with new materials and technologies being worked on and being brought to market. There is even research underway to make compostable plastics from carbon dioxide.
The compostable resins for the most part mimic plastic properties, and different resins have different properties related to heat resistance, tensile strength, impact resistance, MVTR, oxygen barrier etc. One of the main compostable resin PLA, for example has a heat resistance of only 110F, while other compostable resins can have a much higher heat resistance.
Bioplastics can take different length of times to totally compost, based on the material and are meant to be composted in a commercial composting facility, where higher composting temperatures can be reached and is between 90-180 days. Most existing international standards require biodegradation of 60% within 180 days along with certain other criteria for the resin or product to be called compostable. It is important to make the distinction between degradable, biodegradable and compostable. These terms are often (incorrectly) used interchangeably.
A plastic therefore may be degradable but not biodegradable or it may be biodegradable but not compostable (that is, it breaks down too slowly to be called compostable or leaves toxic residue).
Product | Home Composting | Commercial Composting |
---|---|---|
Fiber Plates, Takeout Containers, Bowls, Cups and Trays | Up to 6 months | 1-3 months |
PLA Cold Cups, Clear Containers, Straws | Not recommended | 3-6 months |
TPLA Heat Resistant & Non Heat Resistant Utensils | Not recommended | 3-6 months |
Trash/Kitchen Bags | Up to 1 year | 2-4 months |
The rate of biodegradation for different biocompostables 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 these 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. Composting utensils at home is not recommended, due to their thickness and they may not break down for few years. Similarly, PLA products are not recommended to be composted at home.
There are currently few international organizations which have established standards and testing methods for compostability, namely:
The ASTM, CEN and DIN standards specify the criteria for biodegradation, disintegration and eco-toxicity for a plastic to be called compostable.
Tags: Compostable Materials
Written by
World Centric
Read time
6 minutes
Published on
Dec 2, 2017
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