Synthesis of Poly alkylene dicarboxylate s

The monomers used in the polycondensation reaction for the production of poly(alkylene dicarboxylate)s are basically from petrochemical sources. However, some of them can be obtained from renewable sources. For example, 1,3-propanediol can be produced by fermentation of glycerol, which is a by-product from biodiesel or plant oil production. Succinic acid can be synthesized from glucose or whey by bacterial fermentation in very high yields. [Pg.174]

Instead of vacuum for the removal of the by-product, azeotropic distillation in solution polymerization can be used. Solid-state polymerization, which is often used to increase molecular weights of aromatic polyesters and PLA, is not applicable in case of aliphatic polyesters, due to their low melting temperatures. [Pg.175]

Another approach to increase the molecular weight of polyesters obtained in direct polycondensation is to use chain-extenders, for example through the reaction of oc,(jo-functionalized polyesters with diisocyanates or oxazo-lines Using hexamethylene diisocyanate as a chain extender, an increase in the number average molecular weight from 33 000 to 72 000 g moU for copolymers with butylene succinate and butylene adipate units was reported. [Pg.176]