Plastics
Plastic is a versatile synthetic material made from a wide range of organic polymers. It can be shaped when soft and set into a rigid or slightly elastic form. Plastics are always organic and can be either fossil-based or bio-based.
Types of Plastics: Fossil-Based and Bio-Based
Fossil-Based Plastics: Derived from non-renewable fossil fuels.
Bio-Based Plastics: These are made fully or partially from renewable biological resources (biomass) rather than fossil fuels. However, being bio-based doesn’t automatically make a plastic biodegradable or compostable.
Biodegradability and Compostability
Biodegradability: This refers to the ability of a material to be broken down by microorganisms into water, CO2, and biomass. The process depends on the material’s chemical structure, not its origin. Thus, some fossil-based plastics can be biodegradable, while some bio-based plastics may not be.
Compostability: A subset of biodegradability, compostable plastics must meet specific standards, such as breaking down into non-toxic components within a certain timeframe in industrial composting facilities.
Pros and Cons of Bio-Plastics
Pros:
Renewable Feedstock: Reduces reliance on fossil fuels by using renewable resources.
Circular Solutions: Bio-plastics from third-generation feedstock, such as agricultural waste, offer a more sustainable solution.
Lower Emissions: Production often results in lower greenhouse gas emissions compared to fossil-based plastics.
Recyclability: Bio-plastics can be recycled mechanically or composted if they meet compostability criteria.
Cons:
Land Use: First-generation feedstock may threaten ecosystems and food security.
Agricultural Risks: Intensive farming practices can harm the environment through pesticide use, soil erosion, and high water consumption.
Feedstock Types for Bio-Plastics
First Generation: Made from food crops like corn or sugarcane. While common, this type of feedstock can pose risks to food security and ecosystems.
Second Generation: Derived from non-food crops like cellulose or algae. These are preferable as they pose fewer land-use issues.
Third Generation: Comes from organic waste and non-edible by-products like straw, corn stover, or food production waste. This is the most sustainable option, as it utilizes materials that would otherwise be discarded.
Types of Decomposition
Biodegradation: The process where materials break down into CO2, water, and biomass with the help of microorganisms. The effectiveness and speed depend on environmental conditions like temperature, humidity, and the presence of microorganisms.
Compostability: Compostable plastics must degrade at least 90% within 12 weeks under specific industrial composting conditions. They must not leave behind any harmful residues.
Oxo-Biodegradation: This involves conventional plastics with additives that cause them to fragment into microplastics. However, these fragments do not biodegrade fully, leading to environmental pollution.
Certifications
Bio-Plastics Certification:
The biobased carbon content in materials is measured using the 14C-method (EU standard: CEN/TS 16137; US-standard: ASTM 6866). This certification indicates the percentage of renewable material in the plastic.
Biodegradability and Compostability Certification:
Reliable certifications include ISO 17088, EN 13432 / 14995, and ASTM 6400 or 6868. These standards specify the conditions and timeframe within which a material should biodegrade or compost.
Conclusion
Understanding the different types of plastics and their decomposition processes is crucial for making informed choices, especially as the world shifts towards more sustainable practices. Certifications play a key role in ensuring the materials you choose are both effective and environmentally responsible.