Insight to Cellulose–Polycarboxylic Acid Intermolecular Interactions Using TG and DSC Thermal Analysis Tools

Abstract

Interactions between polycarboxylic acids and cellulose was evaluated by using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) profiles of their mixtures. TGA, DSC of cellulose and acids were recorded as baseline data and peak shifts were calculated by subtracting the peak maximum values of cellulose from that of cellulose-polycarboxylic acid mixtures. In TGA, DL-tartaric and citric acid with cellulose mixtures showed the largest positive shifts of +58 and +23°C in the derivative-TGA second peak. In addition, DL-tartaric and citric acid showed the smallest cellulose DTGA peak 1 area/peak 2 area ratios of 0.50 and 1.58 respectively. In DSC the largest cellulose dehydration peak shifts of +39 and +21°C were recorded for DL-tartaric and citric acids. In acids studied, polycarboxylic acids with one or more hydroxyl groups are more strongly interacting with cellulose in the solid state. The strong interactions of these acids are probably due to their ability to wrap round the polysaccharide chains forming multiple hydrogen bonding between –COOH and –OH of acid with –OH groups of cellulose.