Use of carboxylic acid mixtures derived from biomass treatment for lactic acid based polyols

Abstract

Carboxylic groups affect LAC polymerization. LAC polymerization is produced by polycondensation because it has a carboxyl group and a hydroxyl group in terminal position. Generally, oxalic acid (OXA), formic acid (FA) and acetic acid (AA) are by-products of the processes of conversion of carbohydrates to LAC. FA and AA can be easily separated by stripping. On the contrary, OXA remains in the mixture. OXA contains two terminal carboxyl groups which would produce a higher proportion of carboxyl groups, favoring chain termination, obtaining lower molecular weight of a copolymer of LAC and OXA. To avoid this termination, a diol is added, thus balancing the ratio of carboxyl and hydroxyl groups.The aim of this work was to evaluate the production of polyesters from LAC in a mixture of organic acids, as could be found in a pulping spent liquor.