Degradable lunch box production line- PLA synthesis methodThe polylactic acid (PLA) of the degradable lunch box production line is a new type of bio-based renewable biodegradable material, made of starch raw materials proposed by renewable plant resources (such as corn, cassava, etc.). Starch raw materials are obtained through saccharification, and then fermented with a certain strain to produce high-purity lactic acid, and then a certain molecular weight polylactic acid is synthesized through chemical synthesis. It has good biodegradability. After use, it can be completely degraded by microorganisms in nature under certain conditions. It produces carbon dioxide and water without polluting the environment, which is very beneficial to environmental protection and is recognized as an environmentally friendly material.
There are usually three methods for the synthesis of PLA in the degradable lunch box production line. One is the direct condensation of lactic acid. The method has a simple production process and is an important way to reduce the cost of PLA. However, when the polycondensation reaction progresses to a certain extent, the system will be in equilibrium, so it is difficult to obtain high molecular weight PLA.
The second method to degrade the lunch box production line is to synthesize lactide from lactic acid first, and then polymerize it by ring-opening under the action of a catalyst. At present, this method is generally used to prepare high molecular weight PLA, but this method will affect the purity of the catalyst and the purity of the monomer during the polymerization process. It is required that even a small amount of impurities will make the molecular weight of PLA less than 100,000. Polymerization conditions such as temperature, pressure, type and amount of catalyst, reaction time, etc. will have a great impact on the molecular weight of PLA, so the synthesis of high molecular weight PLA is a Technical Difficulties.
There is also a solid-phase polymerization method in the degradable lunch box production line, which is to polymerize the low molecular weight resin obtained by the direct polymerization method at a temperature between Tg and Tm under reduced pressure vacuum to increase its degree of polymerization and increase its molecular weight. Thereby improving material strength and processing performance.