Why is polypropylene material originated in Wellington, USA

DateTime:Dec,02,2022 / View: 47

Polylactic acid PLA does not exist in nature.

It is generally made by artificial synthesis, while lactic acid as raw material is produced by fermentation.

Polylactic acid is a kind of synthetic linear aliphatic polyester. High relative molecular weight polylactic acid can be obtained through chemical polymerization of lactic acid cyclization dimer or direct polymerization of lactic acid. Polylactic acid ( PLA ) has good biodegradability, good biocompatibility and bioabsorbability, and will not leave any environmental problems after degradation. It has been considered as the most promising biodegradable polymer material in the medical field, so its research and development is extremely active. Today, let's take a look at the history of PLA!

Poly (lactic acid), as a kind of high molecular polymer material, has attracted people's attention for a long time. In 1913, the French synthesized poly (lactic acid) by means of polycondensation. However, its yield is low, its molecular weight is small, and its mechanical properties are poor, so it has no practical value as a structural material. Later, due to the use of polyethylene, polypropylene, and polyvinyl chloride, which are difficult to degrade, resulting in increasingly serious white pollution, people began to imagine using biodegradable PLA to replace general polymer products. Due to the PLA production technology at that time, the synthesized PLA has low molecular weight and poor mechanical strength, so it has no merit as a structural material.

In 1954, DuPont (DuPont, USA) began to prepare polylactic acid by indirect method, that is, first prepare lactide, and then conduct ring opening polymerization of the purified lactide to obtain high molecular weight polylactic acid. (Note: Dupont scientist Wallace Carothers is known as the father of polymer chemistry. As early as 1932, he reacted lactic acid in the presence of solvent and vacuum to obtain polylactic acid. However, because the melting point of the synthetic polylactic acid was too low, the production cost was too high, and the corresponding application could not be carried out, Carothers gave up the research on polylactic acid and invented nylon.)

Since the 1990s, due to the growing awareness of environmental protection, people have paid more and more attention to degradable materials, especially biodegradable polylactic acid. People have focused on the performance, synthesis technology and process improvement of polylactic acid, focusing on the improvement of modifier processing technology. The research in this period is very active and has achieved certain results.

At present, the research and development of PLA in China is still in the stage of laboratory research. Although certain progress has been made, it is still far from industrial production. Many foreign companies have been committed to the research and production of this field for a long time. Some products have been industrialized, but the applied PLA is all synthesized by the ring opening polymerization of lactide.



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