Topic 1 on Polylactic Acid: Basic Properties of Polylactic Acid

Polylactic acid (PLA) is a new type of biobased and renewable biodegradable material made from starch raw materials derived from renewable plant resources such as corn and cassava. Starch raw materials are saccharified to obtain glucose, which is then fermented with glucose and certain bacterial strains to produce high-purity lactic acid. Polylactic acid with a certain molecular weight is then synthesized through chemical synthesis methods. It has good biodegradability and can be completely degraded by microorganisms in nature under specific conditions after use, ultimately producing carbon dioxide and water without polluting the environment. This is very beneficial for protecting the environment and is recognized as an environmentally friendly material.

Polylactic acid, also known as polylactide, belongs to the polyester family. Polylactic acid is a polymer obtained by polymerizing lactic acid as the main raw material. The raw material source is abundant and can be regenerated, mainly using corn, cassava, and other raw materials. The production process of polylactic acid is pollution-free, and the product can be biodegraded, achieving circulation in nature, making it an ideal green polymer material.

Polylactic acid has good thermal stability, processing temperature of 170-230 ℃, and good solvent resistance. It can be processed in various ways, such as extrusion, spinning, biaxial stretching, and injection blow molding. Products made from polylactic acid not only have biodegradability, but also good biocompatibility, glossiness, transparency, hand feel, and heat resistance. They also have certain bacterial resistance, flame retardancy, and UV resistance, making them widely used as packaging materials, fibers, and non-woven fabrics. Currently, they are mainly used in clothing (underwear, outerwear), industries (construction, agriculture, forestry, papermaking), and medical and health fields.

The price of PLA before large-scale industrialization was $1000 per kilogram. Later, through the industrialization research of Professor Ramani Narayan's research group at Michigan State University, large-scale production was achieved. This technology is currently being industrialized by Natureworks.

At present, China is producing a large amount of PLA, mainly by Anhui Fengyuan Group Co., Ltd. and Zhejiang Haizheng Biotechnology Group Co., Ltd. Their current production capacity is 400000 tons/year and 65000 tons/year respectively. NatureWorks in the United States is also continuing production. PLA has many applications, including extrusion, injection molding, film drawing, spinning, and other fields.