What is PLA polylactic acid?

Polylactic acid (PLA) is a polymer material formed by polymerization of lactic acid as raw material, which has the characteristics of non-toxic, high strength, easy processing and excellent biocompatibility, and can be completely reduced after PLA preparation. Because it is very easy to degrade under L work, the mechanical properties are reduced, and it must be modified by physical methods to expand its application field.
1. Structure and properties of PLA
In 1780, the Sweden chemist Scheele extracted an organic acid from sour milk, called lactic acid. Lactic acid is the product of normal sugar metabolism in the organism, which is based on the starch extracted from some plants as the initial raw material, and the glucose is obtained through enzyme decomposition, and then obtained by fermentation of milk bacteria. The lactic acid molecule has a chiral carbon atom, which can be divided into L-lactic acid and right-handed D-lactic acid according to its optical activity, and the molecular formula is C3H6O3.
Different monomer compositions and sequence distributions in the PLA molecular chain give substances different properties. Polylactic acid has three stereoisomers: polyracemic lactic acid PDLLA (polyDL-lacticacid), polyL-lactic acid (PLLA), and polyD-lactic acid (PDLA). Among them, PDLA and PLLA are crystalline, while PDLLA is amorphous. PDLLA and PLLA are commonly used. For polylactic acid, PLLA and PDLA are degraded into lactic acid through hydrolysis in living organisms, enter the tricarboxylic acid cycle, and are completely absorbed by organisms without toxic effects. Lactic acid, the basic raw material of polylactic acid, is one of the inherent physiological substances of the human body, which is non-toxic and harmless to the human body. In addition, polylactic acid has good mechanical and physical properties, and is suitable for various processing methods such as blow molding and thermoplastic, and is easy to operate. It can be used to process various plastic products, food packaging, fast food lunch boxes and cloths for industry and civil use. Polylactic acid has good moisture-proof, grease-proof and airtightness, stable performance at room temperature, but will automatically decompose under the action of temperature higher than 55 °C or oxygen-rich and microorganisms, and can be completely degraded by microorganisms in nature after use, and finally generate carbon dioxide and water, which does not pollute the environment.
Polylactic acid has good biocompatibility, absorbability, mechanical strength and durability, can withstand various disinfection treatments, and has good processing properties, so it is widely used, mainly in the two fields of environmental protection and medicine. At present, the fully biodegradable bag process made by PLA+PBAT has become mature.