Title
Characterization of a rapidly formed mixed ester of cellulose by phthalic anhydride and low temperature transition mixture under microwave irradiation
Authors
HYUNG-MIN CHOI and JI HWAN PARK

Received October 12, 2016
Published Volume 51 Issue 7-8 July-August
Keywords cellulose, phthalic anhydride, oxalic acid, low temperature transition mixture, microwave irradiation, mixed ester

Abstract
This is the first effort to esterify cellulose with phthalic anhydride and a low temperature transition mixture (LTTM) under microwave irradiation. Oxalic acid-choline chloride mixture (OAC) was used as a representative LTTM. Results indicated that cellulose could be very readily esterified under this OAC. Microwave irradiation allowed a rapid esterification reaction within two minutes. Oxalic acid within the OAC participated as both solvent and reagent. Results revealed that the resulting products were actually mixed esters of cellulose formed by oxalic acid and phthalic anhydride. FTIR and elemental analyses indicated that the difference in esterification rate between phthalic anhydride and oxalic acid depended on the concentration of phthalic anhydride and microwave irradiation time. TGA demonstrated that the reaction of cellulose with higher concentration of phthalic anhydride under longer microwave irradiation increased the carbonization rate of the cellulose under thermal exposure, mainly due to acid degradation. Therefore, this study showed a rapid, yet environmentally-benign cellulose esterification could be possible with phthalic anhydride and OAC under microwave irradiation.