Читать книгу Poly(lactic acid) - Группа авторов - Страница 41

The specifications and allowed impurity levels of lactide monomer for PLA are defined by the polymerization mechanism and the applied catalyst. PLA is commercially produced by ROP of lactides in bulk. The tin(II)‐catalyzed process offers good control over molecular weight and reaction rate provided that it is performed in the absence of impurities such as water, metal ions, lactic acid, or other organic acids. Purification of crude lactides is therefore indispensable for the industrial manufacture of high‐molecular‐weight PLA (M _w > 100 kg/mol). In fact, lactide is the ultimate form of lactic acid, in its dehydrated and purest form.