What are two examples of biodegradable plastics?
Biodegradable plastics are materials that can break down naturally over time, reducing their impact on the environment. These plastics are designed to mimic the properties of conventional plastics but with the added advantage of being able to decompose under certain conditions. While there are several different types of biodegradable plastics available, two notable examples are polylactic acid (PLA) and polyhydroxyalkanoates (PHA).
Polylactic acid (PLA) is one of the most common biodegradable plastics used today. It is made from renewable resources such as cornstarch, sugarcane, or cassava, making it a more sustainable alternative to conventional plastics derived from non-renewable fossil fuels. PLA has gained popularity in various applications, including packaging materials, disposable cutlery, and even 3D printing.
The production of PLA starts with the extraction of starch from raw materials such as corn. The starch is then converted into glucose through a process called hydrolysis. The glucose is fermented by microorganisms to produce lactic acid, which is then polymerized to form PLA. This process greatly reduces the carbon footprint of PLA compared to conventional plastics.
One of the benefits of PLA is its ability to break down into carbon dioxide and water in industrial composting facilities. These facilities provide the ideal conditions, such as high temperature and humidity, for efficient decomposition. Under such conditions, PLA can degrade within a few weeks to a few months, depending on the specific product and composting conditions.
Despite its biodegradability, PLA also has its limitations. One such limitation is its slow decomposition rate under natural conditions, such as in landfills or marine environments. In these environments, where the required conditions for rapid decomposition are absent, PLA can persist for a longer period and may contribute to pollution. Therefore, it is essential to create separate waste management systems or recycling programs specifically for PLA to ensure its proper disposal and maximum environmental benefit.
Polyhydroxyalkanoates (PHA) are another example of biodegradable plastics. PHAs belong to a family of polyesters that are produced by various microorganisms, including bacteria. These polymers accumulate as intracellular granules within the microbial cells and serve as an energy and carbon storage source for the organisms.
PHA production involves the cultivation of specific microorganisms, such as bacteria, under controlled conditions. These microorganisms are fed carbon-rich substrates, such as sugars or plant oils, which they convert into PHA. Once produced, PHA can be harvested and processed into various usable forms, such as films, coatings, or injection molded products.
One of the significant advantages of PHA is its flexibility in terms of decomposition. PHA can degrade under various environmental conditions, including soil, water, and marine environments. Its decomposition time can range from a few weeks to several months or even years, depending on the specific composition and environmental factors.
The versatility of PHA makes it suitable for a wide range of applications, including packaging materials, agricultural films, disposable personal care products, and medical devices. It is also used for controlled-release systems to deliver drugs or fertilizers, ensuring a gradual release over a specified period.
However, the production of PHA is still relatively costly compared to conventional plastics, primarily due to the expenses associated with microbial fermentation and purification processes. Research and development efforts are ongoing to improve the efficiency and reduce the production costs of PHA, making it more economically viable for various applications.
In conclusion, polylactic acid (PLA) and polyhydroxyalkanoates (PHA) are two examples of biodegradable plastics that offer significant environmental benefits. PLA, derived from renewable resources, breaks down in industrial composting facilities, while PHA demonstrates versatility in decomposing under various environmental conditions. Both plastics contribute to reducing the reliance on fossil fuel-derived conventional plastics and offer a more sustainable solution for various industries and applications. With continued research and development, biodegradable plastics show great promise for a greener future.