Esterification of Low Molecular Weight Acids in Cellulose

The interaction between low molecular weight acids dissolved in mineral oil with cellulose has been studied. The formation of esters as a function of temperature has been demonstrated using attenuated total reflection infrared (IR) spectroscopy. Higher temperatures lead to a shift towards ester formation compared to lower temperatures. This reaction might be reversed by exposing the cellulose to an excess of water at elevated temperatures. However, this hydrolysis of the esters will not be complete, leaving some of the initially free acids trapped in the paper as esters. Regarding degradation of the cellulose, only free acids with a carbonyl group available will enhance the break-up of the glycosidic bonds in the cellulose polymer. Therefore it seems more appropriate to use cold water extraction in order to quantify the amount of free acids in the paper/pressboard.