Straws for milk tea cups, takeout containers, and supermarket shopping bags—today, the label "biodegradable" is everywhere. Bearing the mark of environmental friendliness, it has quietly entered our daily lives, becoming a popular choice for many who strive to live more sustainably.
When it comes to biodegradable plastics, many people have questions: where do they come from? How do they break down? And how should we use them properly? Today, let's uncover the mystery behind this eco-friendly material, understand its true nature, and truly practice environmental protection in a scientific and rational way.
01 What is biodegradable plastic?
Biodegradable plastics, simply put, are plastics that can be broken down by microorganisms under specific conditions such as natural environments, composting, or anaerobic digestion, ultimately converting completely into carbon dioxide, methane, water, mineralized inorganic salts, and biomass.
More simply put, it needs to be broken down and digested by microorganisms such as bacteria and fungi in suitable environments, ultimately transforming into substances harmless to the environment without leaving behind microplastic residues—truly achieving "from nature, back to nature."
02 Four Types of Biodegradable Plastics: Where Do They Come From and Where Are They Used?
1. PLA (Polylactic Acid) ——
"Hard shell made from corn," the most widely used, is currently the highest-yielding and most commonly applied biodegradable plastic worldwide.
PLA is made from environmentally friendly raw materials such as starch derived from corn, cassava, or straw, produced through a fermentation process, making it a bio-based material.
It is characterized by transparency and high hardness, but has a rather "stubborn" nature—only in industrial composting environments above 50°C can it degrade rapidly, while it is difficult to break down under normal temperature conditions.
Primarily used for disposable products such as takeout containers and straws, it is also applied in 3D printing materials.
2. PBAT
-- "The soft and pliable thing that most resembles an ordinary plastic bag", flexible and reliable
PBAT is a stable biodegradable material that decomposes without leaving any residue. Its raw materials are derived from petrochemical synthesis and belong to fossil-based materials.
Its greatest advantage is its excellent flexibility, as well as its resistance to tearing and water. The feel is almost indistinguishable from the traditional plastic bags we usually use, and it is very convenient to use.
It is mainly used for manufacturing products such as supermarket shopping bags, express delivery bags, and cling film, which require excellent flexibility.
3. PHA (Polyhydroxyalkanoates)
——"All-purpose microbial product", with great potential as a substitute
PHA is a bio-based material synthesized through the fermentation of microorganisms such as bacteria. It is also the most promising safe material that can fully replace traditional plastics at present.
Its biocompatibility is extremely excellent. It does not require specific industrial conditions and can be directly degraded in seawater, freshwater and soil, being very friendly to the environment.
It is mainly applied in high-end packaging, medical sutures, and marine environmental protection products, etc., which have high requirements for safety and environmental protection.
4. PBS (Polybutylene Succinate)
——"The heat-resistant champion", with versatile application scenarios
The raw materials for PBS are quite flexible. They can be produced through biological fermentation or synthesized via the petroleum route, balancing environmental friendliness and practicality.
Its core feature is its high temperature resistance. It can remain stable even in environments above 100℃. At the same time, it can be degraded in compost and naturally decomposed in the soil.
It is mainly used for manufacturing disposable heat-resistant tableware, agricultural films and other products that need to withstand certain high temperatures.
03 Be vigilant: Biodegradable plastics are not "able to decompose anywhere"
1. PLA/PBAT cannot be achieved without the support of "high-temperature factories"
Many people mistakenly believe that biodegradable plastics can decompose quickly just by being thrown away randomly. However, this is not the case. PLA and PBAT can only be completely degraded within 1 to 6 months under specific conditions of industrial composting - high temperature, high humidity, and dense microorganisms.
If they are casually discarded in normal-temperature soil, in the ocean, or thrown into the household trash bins, the degradation rate of PLA is almost the same as that of ordinary plastics. It may take several years or even longer for them to decompose, and thus will not have an environmental protection effect.
2. Throwing them randomly will instead produce "microplastics", causing secondary pollution.
There are also some materials labeled as "photo-degradable". If the degradation reaction does not occur under sufficient light conditions, they are buried in the soil. Eventually, they will break down into tiny microplastics, which not only fail to achieve environmental protection but also cause secondary pollution, thereby endangering the ecological environment.
The experts clearly stated: Only biodegradable plastic made from biological sources is a truly environmentally friendly solution; regardless of the type of degradable plastic, the act of carelessly discarding it will still cause environmental pollution.
04 How to make a reliable purchase? Just look for this label.
The country had already implemented the unified standard for degradable plastics (GB/T41010-2021) in 2021. When purchasing, simply make sure to pay attention to the following 3 points, and you can avoid the "fake environmental protection" trap:
1. Check the material labels: The specific materials such as PLA, PBAT, PHA must be clearly indicated. Products that only label "degradable" without specifying the exact type should be rejected.
2. Observe degradation environment: It is necessary to clearly indicate whether it is "industrial composting" or "soil degradation", to avoid failure of degradation due to environmental mismatch;
3. Check the unified logo: Identify the green double "j" circular symbol (the initial letters of the words "degradable"), as this is the core logo that complies with the national standard.
05 This environmental performance report (data speaks for itself)
The environmental benefits of degradable plastics are not just empty slogans; they are backed by solid data:
Significant carbon reduction: PLA plastic bags can reduce carbon emissions by 70% compared to traditional PE plastic bags;
Outstanding long-term benefits: Since the implementation of national standards five years ago, it is estimated that 20 billion traditional plastic bags can be saved each year, saving 1.2 million tons of oil and reducing carbon emissions by 840,000 tons, contributing greatly to the reduction of plastic use and carbon emissions.
06 Final Note
Biodegradable plastics are a gentle gift bestowed upon nature by technology. They are an important assistance for us in addressing plastic pollution and protecting the ecological environment. However, they are definitely not an excuse for wasteful behavior.
It carries the beautiful expectations of reducing plastic use and carbon emissions. Only by correctly classifying and properly disposing of them can they truly return to the soil and give back to nature, completing the environmental protection loop from "creation" to "decomposition". May we all recognize the value of biodegradable plastics, not blindly follow trends, and not randomly discard them. Let's care for the green mountains and clear waters with our hearts, and ensure that every environmental protection choice can truly nourish this land on which we depend for survival.
