what are compostable bags made of?
Compostable bags have gained popularity in recent years as an eco-friendly alternative to traditional plastic bags. These bags are designed to break down naturally and quickly, leaving behind no harmful residues or microplastics. They are often used for various purposes, such as grocery shopping, waste disposal, and packaging. But what exactly are compostable bags made of, and how do they differ from conventional plastic bags?
Compostable bags are primarily made from plant-based materials, such as cornstarch, vegetable oil, or other organic substances. These materials serve as the basis for creating bioplastics, which have similar properties to conventional plastic but are much more environmentally friendly. The primary benefit of using plant-based materials is that they are renewable resources, unlike fossil fuels, which are used to produce traditional plastics.
One common material used to make compostable bags is polylactic acid (PLA) derived from cornstarch or sugarcane. PLA is created through a fermentation process that converts the natural sugars in these plants into lactic acid. The lactic acid is then polymerized to create a PLA resin, which can be molded and shaped into various products, including compostable bags. PLA-based bags have gained popularity due to their transparency, durability, and ability to be printed on.
While PLA is the most common material, compostable bags can also be made from other biodegradable polymers. One such option is polyhydroxyalkanoates (PHA), which are produced by bacteria during the fermentation of organic materials. PHA-based bags have similar characteristics to PLA bags but have the added advantage of being more flexible and resistant to high temperatures. This makes them suitable for a wider range of applications.
Apart from the polymer itself, compostable bags often contain other additives that enhance their properties. These additives include plasticizers, which improve flexibility, and reinforcing fibers, which increase strength and durability. These additional components can also be derived from renewable resources, ensuring the bags remain fully compostable.
It is crucial to note that while compostable bags are made from plant-based materials, not all bags marketed as "biodegradable" or "eco-friendly" are truly compostable. Some bags may claim to be biodegradable but still contain a significant amount of conventional plastic, which takes a long time to degrade and can harm the environment. Therefore, it is crucial to look for certifications such as the "Certified Compostable" logo from organizations like the Biodegradable Products Institute (BPI) or the European standard EN 13432 when selecting compostable bags.
When compostable bags reach the end of their life cycle, they can be broken down in industrial composting facilities, where specific conditions are provided to accelerate their decomposition. These facilities typically maintain a temperature of around 60°C, along with a mixture of organic waste, oxygen, and moisture. Under these conditions, compostable bags can degrade within a few months, leaving behind only carbon dioxide, water, and biomass.
It is worth mentioning that compostable bags will not break down in a home composting environment or simply when disposed of in a landfill or regular trash bin. These environments lack the necessary conditions to facilitate rapid decomposition. Therefore, it is essential that compostable bags are sent to the appropriate composting facilities to ensure they break down as intended.
In conclusion, compostable bags are made primarily from plant-based materials like cornstarch, sugarcane, or other organic substances. Polylactic acid (PLA) and polyhydroxyalkanoates (PHA) are common polymers used in their production. These bags offer a sustainable alternative to traditional plastic bags, breaking down into harmless components within a few months under specific composting conditions. However, proper disposal in designated composting facilities is essential for their effective decomposition. As consumers, it is crucial to choose certified compostable bags and educate ourselves about the best practices for their disposal to ensure a greener and more sustainable future.