Polylactic acid is one of the most widely used materials biodegradable utensils in the field of 3D printing, and it is also the most widely used material in FDM 3D printers. PLA has always been biodegradable, so is PLA really biodegradable?

Polylactic acid, also known as PLA, is based on thermoplastic engineering plastics. The extrusion time temperature is 170°C-230°C. It is often used as a material for FDM 3D printers in the form of wire. It has the advantages of simplicity, convenience, ease of use, and non-toxicity.

Pla is composed of lactic acid units. Lactic acid is a small organic acid that exists in many foods in our daily lives, such as bread, yogurt, and corn. In theory, any substance containing glucose can be converted into lactic acid molecules.

The crystallinity of lactic acid is relatively low, which causes polylactic acid to exhibit weaker mechanical properties and a lower glass transition temperature. So PLA is suitable for 3D printing, but the finished product is relatively brittle.

In order to be able to obtain better performance for the company, the material chamber will add some other ingredients to the PLA to obtain the corresponding performance, such as improving the flexibility and making the printed parts not brittle.

During production, the material chamber first extracts lactic acid from the raw materials. Corn is one of the commonly used raw materials because it contains a considerable amount of glucose. The Materials Chamber of Commerce extracts starch from corn through a wet milling process. Then add other chemicals and heat to separate the glucose. Then the glucose is fermented to obtain lactic acid monomer. Finally, through polymerization or condensation, the lactic acid molecules are condensed together to obtain PLA.

Therefore, in theory, polylactic acid is a bioplastic with low crystallinity (the lower the crystallinity, the easier it is for biodegradable microorganisms to chemically decompose the material), and it is easier to degrade than petroleum-based plastics. However, due to the addition of other ingredients, the crystallinity will increase during the polymerization process. These factors can prolong the degradation time of polylactic acid.

Moreover, PLA degradation requires certain social and environmental development conditions. Someone has done such an experiment. Objects 3D printed using PLA materials can be buried in the backyard soil for two years. As a result, there is no sign of degradation at all. In fact, if PLA products are thrown in the garbage dump or buried in the soil, the natural biodegradation of PLA products will take hundreds of years.

The PLA degradation process needs to continue to meet the following important conditions: 1. A large number of microorganisms; 2. High temperature, above 30 ℃, microorganisms will develop and begin to degrade PLA; 3. Humidity, the higher the humidity, the higher the hydrolysis efficiency high. It can be said that an environment that can meet these conditions at the same time is very rare in nature.

Therefore, it can be concluded that polylactic acid is biodegradable, but it takes at least several hundred years in the natural environment. However, compared with petroleum-based plastics, the PLA’s environmental friendliness is still much higher. Petroleum-based plastics have existed in the natural environment for hundreds of years and can only be decomposed, and the decomposition of the environment will still have an impact.