Biodegradable plastics VS recycled plastics

Biodegradable plastics VS recycled plastics
Plastic is one of the most important basic materials in modern industry. According to statistics from Our World in Data, from 1950 to 2015, humans produced a total of 5.8 billion tons of waste plastic, of which more than 98% was landfilled, abandoned or incinerated. Only a few To 2% is recycled.

According to statistics from Science magazine, due to its global market role as a global manufacturing base, China ranks first in the world in the amount of waste plastics, accounting for 28%. These waste plastics not only pollute the environment and endanger health, but also occupy valuable land resources. Therefore, our country has begun to attach great importance to the control of white pollution.

In the 150 years after the invention of plastic, three large-scale plastic garbage dumps were formed in the Pacific Ocean due to the action of ocean currents.

Only 1.2% of the world’s 65-year plastic production has been recycled, and most of the rest is buried under human feet, waiting for 600 years to degrade.

According to IHS statistics, the global plastic application field in 2018 was mainly in the packaging field, accounting for 40% of the market. Global plastic pollution also mainly came from the packaging field, accounting for 59%. Packaging plastic is not only the main source of white pollution, but also has the characteristics of being disposable (if recycled, the number of cycles is high), difficult to recycle (the channels for use and abandonment are scattered), low performance requirements and high impurity content requirements.

Biodegradable plastics and recycled plastics are two potential options for solving the white pollution problem.
Biodegradable plastic

Biodegradable plastics refer to plastics whose products can meet the performance requirements for use, remain unchanged during the storage period, and can degrade into environmentally harmless substances under natural environmental conditions after use.

0 1 Degradation process of degradable plastics

0 2Classification of degradable plastics

Biodegradable plastics can be classified by different degradation methods or raw materials.

According to the classification of degradation methods, degradable plastics can be divided into four categories: biodegradable plastics, photodegradable plastics, photo and biodegradable plastics, and water-degradable plastics.

At present, the technology of photodegradable plastics and photo- and biodegradable plastics is not yet mature, and there are few products on the market. Therefore, the degradable plastics mentioned hereafter are all biodegradable plastics and water-degradable plastics.

According to the classification of raw materials, degradable plastics can be divided into bio-based degradable plastics and petroleum-based degradable plastics.
Biodegradable plastics are plastics produced from biomass, which can reduce the consumption of traditional energy sources such as petroleum. They mainly include PLA (polylactic acid), PHA (polyhydroxyalkanoate), PGA (polyglutamic acid), etc. .

Petroleum-based degradable plastics are plastics produced with fossil energy as raw materials, mainly including PBS (polybutylene succinate), PBAT (polybutylene adipate/terephthalate), PCL (polycaprolactone) ester) etc.

0 3 Advantages of degradable plastics

Biodegradable plastics have their advantages in performance, practicality, degradability, and safety.

In terms of performance, degradable plastics can reach or exceed the performance of traditional plastics in some specific areas;

In terms of practicality, degradable plastics have similar application performance and hygienic performance to similar traditional plastics;

In terms of degradability, degradable plastics can be degraded quickly in the natural environment (specific microorganisms, temperature, humidity) after use, and become fragments or non-toxic gases that are easily utilized by the environment, reducing the impact on the environment;

In terms of safety, the substances produced or remaining during the degradation process of degradable plastics are harmless to the environment and will not affect the survival of humans and other organisms.

The biggest obstacle to replacing traditional plastics at present is that the production cost of degradable plastics is higher than that of similar traditional plastics or recycled plastics.

Therefore, in applications such as packaging and agricultural films that are short-lived, difficult to recycle and separate, have low performance requirements, and have high impurity content requirements, degradable plastics have more advantages as alternatives.

recycled plastic
Recycled plastics refer to plastic raw materials obtained by processing waste plastics through physical or chemical methods such as pretreatment, melt granulation, and modification.

The biggest advantage of recycled plastics is that they are cheaper than new materials and degradable plastics. According to different performance needs, only certain properties of plastics can be processed and corresponding products can be manufactured.

When the number of cycles is not too many, recycled plastics can maintain similar properties to traditional plastics, or they can maintain stable properties by mixing recycled materials with new materials. However, after multiple cycles, the performance of recycled plastics declines greatly or becomes unusable.
In addition, it is difficult for recycled plastics to maintain good hygienic performance while ensuring economy. Therefore, recycled plastics are suitable for areas where the number of cycles is small and the requirements for hygienic performance are not high.

0 1

Recycled plastic production process

0 2 Performance changes of common plastics after recycling
Remarks: Melt index, the fluidity of plastic materials during processing; specific viscosity, the static viscosity of liquid per unit volume

Compared
Biodegradable plastic
VS recycled plastic

1 By comparison, degradable plastics, because of their more stable performance and lower recycling costs, have more alternative advantages in applications such as packaging and agricultural films that are short-lived and difficult to recycle and separate; while recycled plastics have lower recycling costs. The price and production cost are more advantageous in application scenarios such as daily utensils, building materials, and electrical appliances that have a long use time and are easy to sort and recycle. The two complement each other.

2

White pollution mainly comes from the packaging field, and degradable plastics have greater room to play. With policy promotion and cost reduction, the future degradable plastics market has broad prospects.

In the field of packaging, the replacement of degradable plastics is being realized. The application fields of plastics are very wide, and different fields have different requirements for plastics.
The requirements for plastics in automobiles, home appliances and other fields are that they are durable and easy to separate, and the amount of single plastic is large, so the status of traditional plastics is relatively stable. In the packaging fields such as plastic bags, lunch boxes, mulch films, and express delivery, due to the low consumption of plastic monomers, they are prone to contamination and are difficult to separate efficiently. This makes degradable plastics more likely to become a substitute for traditional plastics in these fields. This is also verified by the global demand structure for degradable plastics in 2019. The demand for degradable plastics is mainly concentrated in the packaging field, with flexible packaging and rigid packaging accounting for 53% in total.

Biodegradable plastics in Western Europe and North America developed earlier and have begun to take shape. Their application areas are concentrated in the packaging industry. In 2017, shopping bags and production bags accounted for the largest share (29%) of the total consumption of degradable plastics in Western Europe; in 2017, food packaging, lunch boxes and tableware accounted for the largest share (53%) of the total consumption of degradable plastics in North America. )

Summary: Biodegradable plastics are a more effective solution to white pollution than plastic recycling.

59% of white pollution comes from packaging and agricultural film plastic products. However, plastics for this type of use are disposable and difficult to recycle, making them unsuitable for plastic recycling. Only degradable plastics can fundamentally solve the problem of white pollution.

For the applicable fields of degradable plastics, performance is not the bottleneck, and cost is the main factor restricting the market replacement of traditional plastics by degradable plastics.