Types of Biodegradable Plastics
Nov 22, 2023
Plastics have created an adverse impact on earth. They stick in the environment for years spreading toxins. They are threatening lives and also contribute to global warming. Researchers and scientists have found a solution in the form of biodegradable plastics. These are a promising replacement for conventional plastics that are made to decompose more quickly in the environment and reduce long-term pollution.
A research on biodegradable plastics by Dr. Layla Filiciotto, and Prof. Dr. Gadi Rothenberg states that - the associated carbon emissions and persistency of plastics challenge the fragile balance of many ecosystems. One solution is using biodegradable plastics. Ideally, such plastics are easily assimilated by microorganisms and disappear from our environment.
Let’s look more closely about biodegradable plastics and types of biodegradable plastics.
What is biodegradable plastic?
A biodegradable plastic can be decomposed by microbes or biological organisms in proper temperature, humidity, and other natural conditions. It is also made up of polymers that are eco-friendly.
Biodegradable plastics are created in a way that allows them to break down or deteriorate when they are exposed to ultraviolet light from the sun, enzymes, bacteria, water, or wind abrasion.
What is biodegradable plastic made of?
Biodegradable plastic is made from renewable raw materials either from plants or animals. Bio-based materials like starch, fossil-based synthetic polyesters, oil-based materials like sugarcane are few common raw materials used to manufacture these kinds of plastics.
Types of Biodegradable Plastics
The biodegradable plastics are divided into 2 main categories - Oxo-degradable plastics and hydro-biodegradable plastics.
often known as oxo-plastics have pro-degradants as additives. These additives are added while manufacturing the common, traditional plastic with the intention to lessen their negative effects on the environment. These types of plastic degrade quickly when exposed to oxygen and ultraviolet (UV) light. This process breaks down oxo-degradable plastics into smaller pieces more quickly than traditional plastics.
are also referred to as water-soluble or water-dispersible plastics. Hydro-biodegradable plastics are made to decompose quickly in the presence of water. It is made of the polymers with hydrophilic (water-attracting) functional groups in their chemical structure. These polymers absorb the water easily. This causes the polymer chains to break and degrade under natural conditions.
The biodegradable plastics can be further divided into 9 divisions based on the method of their manufacturing and degradation.
Polylactic Acid (PLA)
It is made by fermentation of plant sugars like sugarcane or corn-starch. PLA is used to make medical devices, such as screws, pins, plates, and rods. It can also be used to make plastic films and bottles. PLA shrinks when heated and can be used as shrink-wrap material. It usually decomposes within 6 to 12 months.
It is made by fermenting carbon sources or vegetable oils. It is one of the most eco-friendly substitutes for conventional plastics. It is naturally decomposed by microorganisms in a variety of environments, including soil, water, and composting facilities. PHA is used to manufacture packaging materials like bags, containers, and films
Polybutylene Succinate (PBS)
It is made through a chemical synthesis process. PBS-based fibres can be used in clothing, industrial fabrics, and hygiene products. It has excellent mechanical qualities and is a heat resistant polymer and thus can be used to make some automotive components.
Polyethylene (PE) and Polypropylene (PP) Blends
Some biodegradable plastics are made by blending traditional plastics (PE or PP) with biodegradable additives. These blends are known as oxo-biodegradable plastics and undergo a process of degradation when exposed to oxygen and UV light, eventually breaking down into smaller fragments.
Polyethylene Terephthalate (PET)
PET is known for its excellent mechanical properties, including high strength, stiffness, and impact resistance. It is transparent, lightweight, and has good barrier properties. These properties make PET suitable for packaging applications. It is widely used for food storage and packaging.
These plastics are primarily made from renewable sources such as corn or potato starch. They are commonly used in packaging materials and disposable tableware. Starch-based plastics are compostable, breaking down into natural compounds under the right conditions.
Polyvinyl Alcohol (PVA)
It is a synthetic water-soluble polymer that is made when polyvinyl acetate is partially hydrolysed. It is a tasteless and colourless solid. PVA composites, such as PVA gels, are used in a variety of biomedical fields. PVA is widely used in the production of contact lenses. It is often used in artificial heart surgery, drug delivery systems, and wound dressings.
It is a chemically created polymer especially known for its biodegradability. Aliphatic polyesters can degrade into non - toxic substances like carbon dioxide and water when exposed to environmental factors like moisture, heat, and microbial activity. They are intriguing for use in applications involving biodegradable plastics and environmental considerations because of this characteristic.
It is made from a chemical reaction. Polyurethane exists in various forms like rigid foams, flexible foams, coatings, adhesives, and fibres. The fibre created from polyurethane is strong, resilient, and flexible.
More research is being carried out for more and better biodegradable substances in plastics. This leads to the introduction of more types of biodegradable plastics which can be decomposed in less time and are more eco-friendly as well.
Are biodegradable plastics really biodegradable?
The degradation of biodegradable plastics can vary depending on environmental factors. The factors like temperature, humidity, and microbial activity affects the degradation to a high extent. To ensure that biodegradable plastics have a positive environmental impact, it is crucial to take into account the unique requirements and conditions for their degradation.
The biodegradable plastic is tested in controlled conditions of humidity, temperature, UV exposure and even oxygen content. It is usually done in labs. But nature will not always have such controlled elements. Hence sometimes the biodegradable plastics take more time to decompose or even create pollution as their counter plastic materials.
How to make plastic biodegradable?
The most popular way to make plastic biodegradable is to replace the traditional raw materials with biodegradable alternatives as described above. These materials are either plant based or produced chemically. These biopolymers naturally break down into harmless compounds when exposed to environmental conditions conducive to biodegradation.
Apart from this, additives can also be added to traditional raw materials. These additives allow the polymers to break down into smaller units which lead to easier decomposition of plastic. Blending traditional plastics with biodegradable polymers can also yield biodegradable plastic blends.
Engineers and researchers are working on developing plastics with built-in mechanisms for controlled degradation. These materials are designed to break down into harmless components under specific conditions, such as exposure to certain enzymes or UV light. Some chemical modifications to traditional plastics can enhance their biodegradability.
How do biodegradable plastics differ from traditional plastics?
Biodegradable plastics are made to decompose more quickly in the natural environment. Traditional plastics are created using long-lasting polymers derived from petroleum.
Are all biodegradable plastics the same?
No, the composition, biodegradability, and environmental effects of varied biodegradable plastics can differ. Different biodegradable plastics are used for different applications.
How long does it take for biodegradable plastics to break down?
Biodegradable plastics degrade in different time duration depending on type of plastic and the surrounding environment. Some biodegradable plastics can degrade in a matter of months in industrial composting facilities, while others might require more time in natural settings.
Are biodegradable plastics better for the environment?
While biodegradable plastics may help reduce plastic pollution, their environmental impact depends on a variety of factors. This includes how they are disposed of and whether they are handled properly and disposed of in locations that encourage biodegradation.