8.9 Biodegradable materials

Biodegradable materials 

• The working properties, common uses and environmental impact of the following: 

– polylactide (PLA) 

– polyhydroxybutyrate (PHB), e.g. BIOPOL® 

– plastic made from corn/potato starch. 

A biodegradable material is one that will decompose or break down naturally as a result of microbial action.

Can also be referred to as biodegradable plastics.

Conventional oil-based plastics do not break down easily and, since the bulk of domestic waste comes from this source, they have a significant and negative effect on the environment.

Biodegradable plastics are designed to break down under the right conditions.

The majority of biodegradable plastics are derived entirely from renewable sources. 

Starch based polymers are produced from wheat, corn and potatoes (Potatopak).

Polylactide (PLA) is a type of biodegradable plastic used for packaging, gardening products and even some disposable nappies.

They are also used in medical implants and sutures for their ability to dissolve harmlessly into the body over time.

Polylactic acid (PLA), also known as polylactide, is a bioplastic derived from renewable resources such as corn starch or sugarcane. It is a thermoplastic polyester with unique properties that make it a popular alternative to traditional petroleum-based plastics. PLA is known for its versatility and is used in a wide range of applications.

Positives:

• Biodegradable: PLA can decompose in industrial composting facilities under specific conditions.

• Renewable resource: PLA is made from renewable resources, reducing dependence on fossil fuels.

• Versatile: It can be used in various forms, including films, fibers, and molded products.

• Low toxicity: PLA is considered safe for food contact and other applications.

• 3D printing: PLA is a popular material for 3D printing due to its low melting point and ease of use.

Negatives:

• Not compostable at home: PLA requires specific industrial composting conditions to break down.

• Lower heat resistance: PLA has lower heat resistance compared to traditional plastics.

• Mechanical properties: PLA may not be suitable for applications requiring high strength or durability.

• Cost: PLA can be more expensive than some traditional plastics.

• Limited recycling infrastructure: Recycling options for PLA may be limited in some areas.

Typical Uses:

• Packaging: PLA is used for food packaging, films, and containers.

• Textiles: PLA fibers are used in clothing, upholstery, and non-woven fabrics.

• 3D printing: PLA is a popular material for prototyping and hobbyist projects.

• Medical devices: PLA is used in sutures, implants, and drug delivery systems.

• Consumer goods: PLA can be found in disposable tableware, electronics casings, and other products.

Environmental Impact:

PLA has the potential to reduce environmental impact compared to traditional plastics due to its renewable resource origin and biodegradability. However, it is crucial to properly manage PLA waste through industrial composting to realize its environmental benefits. Improper disposal can lead to PLA persisting in the environment, similar to traditional plastics. The environmental impact of PLA production, including resource consumption and emissions, should also be considered.

Corn and potato starch-based polymers, also known as bioplastics, are a fascinating alternative to traditional petroleum-based plastics. Derived from renewable resources like corn and potatoes, these polymers offer a more sustainable approach to material production. While they hold great promise, it's important to consider both their advantages and disadvantages.

Positives:

• Renewable resources: They are made from renewable resources, reducing our dependence on fossil fuels.

• Biodegradable: Under the right conditions, they can break down naturally, reducing the burden on landfills.

• Potentially compostable: Some types can be composted, further reducing waste.

• Reduced carbon footprint: Their production often involves lower greenhouse gas emissions compared to traditional plastics.

Negatives:

• Cost: They can be more expensive to produce than traditional plastics.

• Performance limitations: They may not always match the durability and versatility of conventional plastics.

• Land use concerns: Growing crops for bioplastics can compete with food production and may require fertilizers and pesticides.

• Limited infrastructure: Proper composting or biodegradation facilities may not be widely available.

Typical Uses:

• Packaging: Food packaging, disposable tableware, and carrier bags.

• Agriculture: Mulch films, plant pots, and seed coatings.

• Textiles: Fibers for clothing and other materials.

• Medical: Sutures, drug capsules, and implants.

Environmental Impact:

The environmental impact of corn and potato starch-based polymers is a complex issue. While they offer potential benefits in terms of biodegradability and reduced carbon footprint, it's crucial to consider factors like land use, resource consumption, and the availability of proper disposal methods. A comprehensive life-cycle assessment is needed to fully evaluate their environmental sustainability.