As the name implies, compostable materials are materials that can be degraded into small molecules under certain conditions and after a certain period of time. According to the degradation mechanism, it can be roughly divided into three categories: photodegradable materials, biodegradable materials and photo-biodegradable materials.
In the early days, people would add some degradable ingredients or photosensitizers, such as starch, to traditional plastics without affecting the function of the material.
Under natural conditions, the degradable components degrade first, thus destroying the entire product structure. This will not only help reduce plastic bags, but also accelerate the degradation of refractory components. But this kind of material is not a completely degradable material in the true sense, and it may take a long time before it is completely degraded. Nowadays, some completely compostable materials can replace or are replacing traditional plastics. Next, we will introduce some compostable materials that we can come into contact with in our lives.
1. Starch-based plastics
Starch-based plastics are the most common compostable materials in our lives. For example, it is used in some disposable tableware. Its main raw material is starch. As long as you have the right tools, you can also use the starch in the kitchen at home to make some starch-based compostable materials
2. Polylactic acid (PLA)
You may not have heard of polylactic acid, but you must know lactic acid. Everyone has experienced the feeling of soreness after strenuous exercise. Polylactic acid is a polymer formed by polymerization of hydroxyl and carboxyl groups in lactic acid. Polylactic acid has no pollution in the whole production process, its performance is similar to many plastics, and it has high compatibility with organisms. Therefore, PLA is widely used in packaging, automobile industry, and electronics industry etc.
3. Polyhydroxy fatty acid ester (PHA)
This should be a new term for everyone. PHA is an internal polyester formed in microorganisms. It is a kind of natural polymer biomaterials, and it is a research hotspot of biofunctional materials in recent years. Compared with other degradable materials, PHA can change its composition by controlling the strain and fermentation process. PHA can be as hard as engineering plastics or as soft as rubber. This powerful diversity makes its application range wider, and it is also the focus of research on compostable materials in recent years.
The raw materials of the several completely compostable materials introduced above do not rely on fossil fuels at all, which is of great significance to alleviating the energy crisis. However, without fossil fuels, its raw materials mainly rely on food and microorganisms, which are more expensive than traditional fossil fuels, and it is difficult to form large-scale applications. On the whole, not all compostable materials have reached the standard of engineering plastics, and the processing technology still needs to be improved. Therefore, the popularization of compostable materials still has a long way to go.