What are biodegradable plastics? Biodegradable plastic is a type of plastic capable of breaking down into organic compounds, CO2, H2O, and other biomass under the influence of microorganisms in natural conditions or under biological treatment. The degradation time of biodegradable plastic is typically much shorter than that of conventional plastics, ranging from several months to a few years.
In 2018, the United Nations reported that 127 countries had enacted laws regulating plastic bags, 27 countries had banned or restricted single-use plastics (SUP) and specific plastic materials production, and 63 countries had introduced extended producer responsibility regulations for SUP (Single-Use Plastic). Among the specific material composition requirements for plastic bags, 35 countries supported the use and production of biodegradable plastics.
Since then, various types of biodegradable plastics have garnered significant attention in mainstream media, often seen as promising breakthrough materials in addressing the plastic crisis. This article will provide an overview of the most widely used biodegradable plastics today.
1. Polylactic acid (PLA)
Polylactic acid (PLA) is a type of biodegradable plastic produced from renewable resources, such as corn starch, cassava roots, potato chips, or sugarcane. PLA is a thermoplastic, meaning it can be heated and molded into various shapes.
Polylactic acid (PLA)
PLA finds applications in various industries, including:
- Food Packaging: PLA is used to manufacture biodegradable food packaging, such as food bags, food containers, and drink cups.
- Household Goods: PLA is used to produce biodegradable household items like spoons, forks, knives, and cups.
- Medical Field: PLA is used to manufacture biodegradable medical devices, such as stents and catheters.
- Industrial Applications: PLA is utilized in industrial applications, such as fabric production and machine components.
2. Polyhydroxyalkanoate (PHA)
Polyhydroxyalkanoate (PHA) biodegradable plastic is a type of bioplastic derived from the natural fermentation of sugars or lipids by bacteria. It consists of polyesters made from R-hydroxy alkanoic acids. PHA offers several advantages over traditional plastics, including:
- Biodegradability: PHA can completely biodegrade into CO2, H2O, and biomass in soil, water, or the ocean environment. This helps minimize environmental pollution and protect human health.
- Renewable Raw Materials: PHA is produced from renewable raw materials such as sugars, starch, vegetable oils, and more. This provides a sustainable solution to the issue of fossil resource depletion.
- Good Physical and Chemical Properties: PHA possesses physical and chemical properties similar to traditional plastics, including strength, flexibility, impact resistance, and more. This allows PHA to be used in various applications.
Applications of PHA:
- Packaging: PHA can be used to produce bags, containers, and food packaging.
- Medical Equipment: PHA can be used to manufacture syringes, catheters, surgical instruments, and more.
- Agriculture: PHA can be used to produce organic fertilizers, agricultural materials, and more.
3. Polybutylene succinate (PBS)
Polybutylene succinate (PBS) is a thermoplastic biodegradable polyester derived from biological sources. PBS is a type of plastic that can completely biodegrade into water and carbon dioxide by microorganisms in the natural environment, causing no environmental pollution. PBS is produced from natural raw materials, including:
- 1,4-butanediol: A type of alcohol produced from corn, potatoes, sugarcane, and more.
- Succinic acid: An organic acid produced from sugarcane, corn, and other sources.
Polybutylene succinate (PBS)
PBS can be applied in various fields, including:
- Food packaging
- Medical packaging
- Construction materials
- Technical plastics
4. Polyvinyl alcohol (PVA)
Polyvinyl alcohol (PVA) is a biodegradable plastic produced from vinyl acetate. It is a synthetic polymer, meaning it is synthesized from smaller chemical units. In the case of PVA, the chemical units are vinyl acetate with the chemical formula CH2=CHOCOCH3.
PVA has many useful properties, making it a popular choice in various applications. It is a solid, colorless, odorless material that dissolves in water and has the ability to resist moisture, oil, and chemicals. PVA also has high tensile strength and elasticity, making it an excellent adhesive and protective material.
One of the most important properties of PVA is its biodegradability. PVA can be degraded by microorganisms in soil, water, or air. This makes it a more sustainable choice compared to other plastics, such as polyethylene terephthalate (PET) or polystyrene (PS).
Polyvinyl alcohol (PVA)
PVA is used in various applications, including:
- Paper manufacturing
- Paint and coating production
- Textile fiber production
- Glue and adhesive manufacturing
- Production of medical products
- Packaging product manufacturing
5. Cellulose Acetate (CA)
Cellulose acetate (CA) is a type of biodegradable plastic created from cellulose, a natural polysaccharide found in plants. CA is produced by processing cellulose with acetic acid and acetic anhydride. This process forms acetate linkages between cellulose molecules, making them soluble in organic solvents such as acetone and tetrahydrofuran.
CA possesses several unique physical and chemical properties, making it a versatile and flexible material. It is a lightweight, durable, waterproof, and flame-resistant material. It is also a poor conductor of electricity, making it a suitable choice for electronic applications.
Cellulose Acetate (CA)
CA is used in a variety of applications, including:
- Plastics: CA is used to produce various plastic products, including fabrics, films, tubes, and automotive components.
- Fibers: CA is utilized to manufacture fibers used in textiles, clothing, and accessories.
- Paints and Coatings: CA is used in paints and coatings to create a glossy finish and provide waterproofing.
- Pharmaceuticals: CA is used in certain types of medications and dietary supplements.
6. Polyglycolic Acid (PGA)
Polyglycolic acid (PGA) is a type of biodegradable plastic made from glycolic acid, produced through the fermentation of natural carbohydrate sources like sugar beets, sugarcane, and corn. PGA is a thermoplastic, meaning it can be melted and molded into various shapes.
Polyglycolic Acid (PGA)
PGA has various applications, including:
- Packaging: PGA can be used to manufacture bags, boxes, and other packaging materials. It is a sustainable alternative to traditional plastic packaging because it can biodegrade and does not contain harmful chemicals.
- Medical: PGA is used in various medical applications, such as sutures, screws, and patches. It biodegrades within the body, eliminating the need for surgical removal.
- Industrial: PGA finds use in industrial applications, including electronic components and construction materials. It boasts high strength and corrosion resistance.
7. Polymer Materials Based on Lignin
Biodegradable plastics are plastics with the ability to decompose into safe inorganic compounds, such as CO2, H2O, and biomass, under the action of microorganisms in the natural environment. Biodegradable plastics can be made from renewable sources, such as corn starch, potatoes, and cassava, or from fossil-based materials, such as petroleum.
Polymer materials based on lignin are a type of biodegradable plastic made from lignin, an organic compound found in plants. Lignin is a major component of wood, constituting about 25-35% of the dry wood mass. Lignin exhibits sustainable, sturdy, waterproof, fire-resistant properties and can be broken down into safe inorganic compounds by microorganisms.
Polymer Materials Based on Lignin
Some specific applications of polymer materials based on lignin include:
- Food Packaging: Polymer materials based on lignin can be used to produce food packaging, replacing traditional plastic packaging. This material has antibacterial, waterproof, and gas-resistant properties, protecting food from bacterial contamination and pollution.
- Construction Materials: Polymer materials based on lignin can be used to manufacture construction materials like concrete and bricks. These materials have high mechanical strength, waterproofing, and fire resistance properties, enhancing the durability and load-bearing capacity of construction projects.
- Furniture Materials: Polymer materials based on lignin can be used to produce furniture materials such as tables, chairs, and cabinets. These materials are highly durable, scratch-resistant, and moisture-resistant, increasing the longevity and aesthetics of furniture.
- Automotive and Motorcycle Parts: Polymer materials based on lignin can be used to manufacture automotive and motorcycle parts, such as vehicle exteriors and shields. These materials have high durability, good impact resistance, and corrosion resistance, improving the longevity and performance of vehicles.
- Household Items and Toys: Polymer materials based on lignin can be used to produce household items and toys, such as utensils and children's toys. These materials are highly durable, safe for health, and enhance the longevity and convenience of household items and toys.