Synthesis of polylactic acid

Polylactic acid, there are two synthesis methods, i.e. lactide (cyclic dimer of lactic acid) and the magnessium lactate polymerization of the direct polymerization of lactic acid.
Ring-opening polymerization of lactide production processes: first lactic acid dehydration cyclization made lactide; Then lactide ring-opening polymerization of Lactic acid. Wherein the cyclization and purification of lactic acid is the preparation of lactide difficult and critical, this method can be obtained a high molecular weight polylactic acid, but also to better meet a fiber-forming polymer and a bone fixation material requirements.
Direct polycondensation of lactic acid by direct polymerization of lactic acid refined, is the earliest and most simple way. The production process is simple, but the resulting polymer molecular weight is low and wide molecular weight distribution, the processing performance can not meet the needs of a fiber-forming polymer; but higher than the polymerization reaction under conditions of 180 ℃, resulting polymerization easily oxidized coloring matter, subject to certain restrictions apply.
As the raw material cause, poly poly-d-lactic acid (PDLA), poly-L-lactic acid (PLLA) and poly dL-lactic acid (PDLLA) of the points. Production of fiber commonly used PLLA.