Biodegradable Plastics Q&A
What are Biodegradable Plastics?
Biodegradable plastics are those that can decompose naturally in the environment. The makeup structure of biodegradable plastics makes them easily break down by natural microorganisms, giving an end product that is less harmful to the environment.
As such, biodegradable plastics are perceived to be more eco-friendly due to their environmental benefits, which are hard to deny compared to ordinary plastics.
To minimize environmental pollution, this type of plastic is undoubtedly a better choice but still comes with its downside. Here, we look at how biodegradable plastics are made, their benefits and problems, and examples of their uses.1
How are Biodegradable Plastics Made?
Biodegradable plastics are made in a way that they can breakdown or degrade when exposed to the sun’s ultra-violet radiation, enzymes, bacteria, water, or wind abrasion. They are made from renewable raw materials or all-natural plant or animal materials such as orange peels, corn oil, switchgrass, soybeans, micro-organisms, or starch.
The industrial processing of biodegradable plastics is similar to the manufacture of ordinary plastic, only that the materials used differ and for bio-degradable plastics; they are the materials that can easily break down or decompose.2
What are the main types of biodegradable plastic?
They are mainly categorized into two:
- Bio-plastics; purely made from natural substances such as corn starch. Examples of those made from corn starch include EverCornand NatureWorks. In their manufacturing process, they save energy and emit less carbon as the plants used already have the same amount of carbon.
- Biodegradable plastics; made from traditional petrochemicals but designed to break down faster. They have additives that speed up their rate of decay or breakdown in the presence of oxygen and light. The presence of moisture also accelerates the breakdown process. Mainly, they get a breakdown in the presence of the sun’s UV light with some only breaking down at high industrial-scale temperatures. The most common examples include polybutyrate adipate terephthalate (PBAT), polybutylene succinate (PBS), polyvinyl alcohol (PVOH/PVA), and polycaprolactone (PCL).3
What does oxo-biodegradable mean?
Oxo-biodegradable simply means that the plastic, at the end of its useful life, biodegrades through oxidation in the presence of oxygen, hence the name oxo-biodegradable (oxo stemming from oxygen).1
What is oxidation?
Oxidation is a process in which a chemical substance changes because of the addition of oxygen.2
What is oxo-biodegradable plastic?
Oxo-biodegradable plastic is made by blending a pro-degradant additive (such as EPI or D2W) into the plastic during the extrusion process. The additive causes the molecular structure of plastic to break down when exposed to heat or sunlight. The plastic will eventually be in a state where it can be digested by microorganisms. At this point, the plastic will degrade at a faster rate until it has fully degraded into carbon dioxide, water, and biomass.
Oxo-biodegradable plastic is often referred to as “degradable” plastic, since it does not require a biological process to degrade. Microorganisms will speed up the degradation process, but they’re not required. This gives oxo-biodegradation a distinct advantage over prior methods for degrading plastic.
The degradation time varies depending on the amount of exposure to degradation promoters (sunlight, heat, and microorganisms). This is an optimal situation for consumers. Oxo-biodegradable plastic degrades quickest in the exact situation we want it to: when it becomes litter. If the plastic is used properly it will last many years, but once it becomes litter it could degrade in under 12 months.
In a landfill oxo-biodegradable plastic will degrade quickly if oxygen is available to assist the degradation process. However, unlike other types of degradable plastic, oxo-biodegradable plastic will not release methane as it degrades. This is another advantage over prior forms of biodegradable plastic.3
Why does it take about 2 years for the bags to degrade?
Oxo-biodegradable plastic degrades due to exposure to the elements (sunlight, heat, and microorganisms). Two years is an estimation based on the average conditions. The actual amount of time required to degrade a bag will be longer or shorter depending on the amount of exposure.
We believe this is an optimal situation. Oxo-biodegradable plastic bags degrade fastest in the exact situation we want them to: when they become litter. 3
Is there a standard for oxo-biodegradable plastic?
Yes, The American Society for Testing and Materials (ASTM) recognized oxo-biodegradation and ASTM D6954-04 is the standard guide developed for Exposing and Testing plastics that Degrade in the Environment by a Combination of Oxidation and Biodegradation. 4
Will oxo-biodegradation emit methane?
No, unlike other degradation processes oxo-biodegradation will not emit methane. 3
Are oxo-biodegradable bags as durable as regular plastic?
Yes, during their useful life oxo-biodegradable plastic bags are the same as regular plastic bags. You will not notice a difference until the bag has been exposed to UV light or heat for prolonged periods of time. 3