Polylactic acid, also known as PLA, is a thermoplastic material with an extrusion temperature of 170 ℃ -230 ℃. It is often used as a material for 3D printers in the form of wire, and has the advantages of simplicity, ease of use, and non-toxic properties.
PLA is composed of lactic acid units, which are small organic acids that are found in many foods in our daily lives, such as bread, yogurt, corn, and so on. In theory, anything containing glucose can be converted into lactic acid molecules. The low crystallinity of lactic acid results in PLA exhibiting weak mechanical properties and low glass transition temperature. Therefore, PLA is suitable for 3D printing, but the finished product is relatively brittle.
In order to achieve better performance, the material will add other components to the PLA to obtain corresponding properties, such as improving flexibility and making the printed piece not brittle.
During production, lactic acid is first extracted from the raw materials, and corn is one of the commonly used raw materials because it contains a considerable amount of glucose. The material chamber extracts starch from corn through a wet grinding process. Then add other chemicals and heat to separate glucose. Then glucose is fermented to obtain lactic acid monomers. Finally, lactic acid molecules are condensed together through polymerization or condensation to obtain PLA.
Therefore, in theory, PLA is a type of bioplastics with low crystallinity (the lower the crystallinity of the material, the easier it is for the microorganisms responsible for biodegradation to chemically decompose the material), which is much easier to degrade than petroleum based plastics.
PLA can be said to be one of the most widely used materials in the field of 3D printing, and the material used by the largest number of 3D printers is PLA. PLA has always been marketed as biodegradable, so is PLA really biodegradable?
Yogurt or anything with glucose that people usually drink can become lactic acid, and the lactic acid of PLA consumables comes from corn, which is made from starch raw materials extracted from corn. Therefore, in theory, PLA is a type of bioplastics.
The process and duration of biological degradation largely depend on the environment. For example, heat, humidity, and microorganisms are three necessary factors that affect the degradation rate of PLA.
To degrade PLA materials, the following conditions need to be met:
1. A large number of microorganisms;
2. At high temperatures of 60 ℃, microorganisms will degrade PLA;
3. Wet, the higher the humidity, the higher the hydrolysis efficiency.
If the conditions are met, burying PLA deep in the soil can cause signs of decay within 6 months.The final generation of carbon dioxide and water does not pollute the environment, which is very beneficial for environmental protection and is recognized as an environmentally friendly material.
So, it can be concluded that PLA can be biodegradable, and complete degradation requires specific temperatures and environments. However, compared to petroleum based plastics, PLA is still much more environmentally friendly. Petroleum based plastics have been in the natural environment for hundreds of years and can only decompose, but after decomposition, they still have an impact on the environment. Biodegradable materials are ideal for sustainable development as they ultimately return to nature.
For example, in certain aspects where you want it to automatically degrade and disappear after a certain period of time, such as in orthopedic surgery, degradability is also beneficial. For another purpose, most models need to remain unchanged and do not want them to degrade quickly. If they are placed in a cool and dry place, PLA printed 3D models will last longer.
Unilong is a professional supplier of biodegradable materials. Faced with the current international situation, biodegradable materials have become the main trend of development. We always adhere to the principle of producing biodegradable biomaterials that “originate from nature and belong to nature”.