According to statistics, of the 9 billion tons of plastic products produced in the world, only 9% are recycled, 12% are incinerated, and the remaining 79% end up in landfills or flow into the natural environment; it is estimated that by 2050 In 2018, the global plastic production will exceed 34 billion tons, and the production of waste plastics will be 12 billion tons. At present, as many as 5 trillion plastic bags are used every year in the world. Now the Chinese market is also gradually promoting the use of degradable lunch boxes.
The fundamental reason why traditional plastics bring serious white pollution is their long degradation time, and the biggest advantage of degradable plastics compared with traditional plastics is that the degradation time is short, which can fundamentally solve this problem.
Degradable plastics refer to a class of plastics whose various properties can meet the requirements of use, the properties remain unchanged during the storage period, and can be degraded into environmentally harmless substances under natural conditions after use. This concept first originated in Europe. Western developed countries use degradable disposable utensils with the idea of the circular economy. For example, in the late 1980s, Sweden trial-produced disposable fast food boxes made of potatoes and corn. The most ideal degradable plastic should have the same performance as non-degradable plastic during use, and after use, it can be naturally decomposed into fragments and degraded into macromolecules and small molecules step by step under various natural conditions such as abandonment and landfill. , carbon dioxide, and water.
Europe, which was the first to develop degradable plastics, developed a starch-modified plastic route, which is called the first generation of degradable plastics. This type of starch-based degradable plastic is modified by adding additives such as starch during the polymerization of traditional monomers such as PE (polyethylene), so that the plastic can be cracked into tiny plastic fragments in the environment. However, in later research, it was found that the plastic after it became fragments could not be completely degraded, and it would continue to poison the environment by forming microplastics. Therefore, starch-modified plastics are also called "destructible plastics" (incompletely degradable). Second-generation degradable plastics are photothermally degradable plastics, and their development is also very slow due to strict requirements on degradation conditions such as temperature and light intensity.
Subsequently, degradable plastics were further developed in the Americas. Relying on the rich local biomass resources, the third generation of degradable plastics represented by PLA, namely biodegradable plastics, was born. Under the action of microorganisms ubiquitous in nature such as fungi and algae, the long chains in the polymer are broken, and finally completely decomposed into CO2 and water to achieve complete biodegradation, and the raw materials are derived from the fermentation of corn, etc., belonging to bio-based source materials. Later, other biodegradable plastics such as PBS, PBAT, and PHA have also been developed one after another, which can theoretically achieve real green environmental protection and no environmental toxicity. All in all, the biggest feature of inorganic material nucleating agents is that they are widely available, cheap, and easy to obtain, and can promote the nucleation and crystallization of biodegradable plastics. However, due to its poor compatibility with the matrix polymer, it is easy to cause the performance of plastic products to decline or become unstable, which limits its application range.
Raw plastics are one of the most important products in the chemical industry. Due to the advantages of plastics with strong functionality, good processability, and easy large-scale production, they continue to create new applications and continue to replace other traditional materials. In 2019, global plastics output has reached 400 million tons, and it is the most important material for building human society. Traditional materials such as wood, stone, glass, and metal will decompose into various forms after a period of time and return to the natural cycle, but plastics are completely man-made, and most of them are difficult to decompose after hundreds of years. It has formed the "white pollution" problem that society is very concerned about. In order to not only enjoy the performance and cost advantages of plastics but also alleviate the harm of waste plastics to the environment, degradable plastics came into being.
The development of degradable plastics has been slow in the early stage. The main reason is that the production cost is high and the implementation policy is not strong enough. However, since China banned the import of foreign waste in 2018, the industry trend has changed significantly. In the past, although overseas developed countries produced a large amount of plastic waste, by exporting to China and other regions, the huge external cost was solved with a small cash cost; while China has borne additional external costs, and the burden is getting heavier and heavier. . In order to solve the serious waste problem, China has begun to ban the import of foreign garbage, which has caused a sudden increase in the processing cost of developed countries. Therefore, it can be seen that European countries have successively introduced mandatory policies for plastics since 2018, and domestic policies have also begun to increase. Strict, so we believe that degradable plastics have entered an industry explosion period, and polylactic acid (PLA) and PBAT are the most promising materials.
Biodegradable plastics cover a wide range, including starch, wood powder, bamboo powder, and other organic biomass raw materials filled with complexes. The surface modification of organic fillers is critical to the processing and application performance of products. Coupling agents or reactive functionalized polymerization Physical auxiliaries are an indispensable type of auxiliaries for these products. Commonly introduced reactive functional groups are isocyanate groups, epoxy functional groups, oxazolines, acid anhydrides, and the like.