What are the Classifications of Biodegradable Plastics?

Publish Time: 2023-12-14 14:55

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In the realm of sustainable materials, the biodegradable plastics plays a pivotal role. These plastics, categorized based on their degradation mechanisms and raw materials, contribute significantly to environmentally friendly practices. In terms of degradation mechanisms, biodegradable plastics can be classified into biologically degradable plastics, photo-degradable plastics, photo/bio-degradable plastics, and water-degradable plastics. Meanwhile, the classification based on raw materials distinguishes between bio-based plastics and petroleum-based plastics. This classification system provides a comprehensive overview of the diverse and eco-conscious landscape of biodegradable plastics.

Classification by Degradation Method

Category	Biodegradable Plastics	Photodegradable Plastics	Photobiodegradable Plastics	Water-Soluble Plastics	Bio-based Plastics	Petroleum-based Plastics
Introduction	Plastics that can be decomposed by microorganisms such as bacteria, fungi, algae, etc., into low-molecular-weight compounds under certain conditions.	Plastics that gradually decompose under the influence of sunlight. - Copolymer Type: Synthesized from carbon monoxide or carbon-containing monomers and olefin monomers. - Additive Type: Plastics with added photosensitizers like benzoin, benzoin methyl ether, etc.	Fusion of both photodegradable and biodegradable characteristics.	Plastics that can completely degrade in moist natural environments.	Plastics generated from natural substances like starch, soy, cellulose, lignin, plant oils, etc., under the action of bacteria, enzymes, etc.	High molecular compounds formed through polymerization or polycondensation reactions using fossil fuels such as petroleum as raw materials.
Representative Products	PLA, PHA, PBAT, etc.	Photodegradable PE, PP, PVC, PS, etc.	Not yet in mass production.	Starch-based Plastics	PLA, PHA, Polysaccharide derivatives, Amino acid polymers	PCL, PBSA, PBAT
Advantages	Similar performance to conventional plastics, good degradability, and high safety.	Simple production process and low cost.	Combines the advantages of both photodegradable and biodegradable materials.	Rapid and complete degradation in a short time, leaving no trace, no pollution, and low cost.	Abundant raw material sources, free of toxic substances, reduced pollution, and similar performance to conventional plastics.	Biodegradable
Disadvantages	Complex production process compared to conventional plastics.	Degradation process is influenced by the intensity of light.	Difficulties in mass production.	Poor performance, narrow application fields, and residual content in starch degradation.	Higher cost.	Higher cost.

Biodegradable plastics encompass various types, with prominent examples including PBAT, PLA, PBS, PCL, PHA, and more. PLA and PBAT, in particular, dominate the landscape, serving as key alternatives to traditional plastics. PLA, derived mainly from lactic acid, stands out as one of the most common biodegradable plastics. It exhibits high hardness, transparency, good thermoplasticity, and resilience, making it a cost-effective material in the biodegradable plastics industry. PLA finds applications in diverse fields such as food packaging, disposable tableware, and medical materials.

On the other hand, PBAT, with its excellent extensibility and tensile strength, excels in film formation and is widely used in packaging and agriculture due to its ease of film blowing. The research and development of biodegradable plastics have evolved over nearly six decades, progressing from the first-generation starch-modified plastics to the second-generation photo-thermal degradable plastics, and finally to the third-generation bio-degradable plastics. The current focus of research is on the third generation of bio-degradable plastics, characterized by excellent performance and rapid degradation in natural environments (under specific microorganisms, temperature, and humidity). These plastics pose no risk of white pollution, making them a transformative direction for future green development.

Performance and Applications of Biodegradable Plastics

Biodegradable Plastic Type	Performance	Main Applications
PBAT	Combines characteristics of PBA and PBT. Performance is close to traditional petroleum-based materials, exhibiting good tensile strength and elongation at break. Excellent film-forming properties.	Plastic packaging films, agricultural mulch films, disposable utensils, etc.
PLA	High hardness, high transparency, toughness, and high permeability to water vapor and oxygen. Ideal for transparent containers and raw materials for pipe manufacturing.	Daily life, agriculture and forestry, environmental protection, textiles, composite materials, tissue engineering, and 3D printing materials.
PBS	Similar performance to PBAT; good processing properties. Cost reduction achieved by co-wetting with a large amount of fillers such as calcium carbonate and starch.	Food packaging materials, foam packaging materials, daily necessities bottles, agricultural films, slow-release materials for pesticides and fertilizers, etc.
PCL	Good biocompatibility; melting point is 60-63℃.	Mainly used in high-value-added packaging materials and medical materials, also applicable to 3D printing consumables.
PHA	Good biocompatibility; excellent drug permeability, allowing for stable, prolonged drug release; strong biodegradability under various environmental conditions.	Used in high-value-added fields such as medical, pharmaceuticals, and chemical products.

Comparison of Third-Generation Biodegradable Plastics

Generation Category	Technological Pathway	Degradation Characteristics	Pros and Cons
Modified Powder-Type	Traditional monomers as the base material; additives such as starch are introduced.	General degradation in ambient conditions; degradation efficiency is moderate.	Cannot completely degrade; challenging to recycle.
Photothermal-Type	Traditional monomers as the base material; addition of photosensitizers.	Degradation under light conditions; the degradation induction period can be controlled by photodegradation regulators.	Significant influence of environmental conditions during the degradation process.
Biodegradable Plastics	Base material is inherently biodegradable.	High efficiency in compost degradation.	Complete degradation possible; high production costs.

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