10 g of microcrystalline cellulose (MCC) was mercerized in 20 % of 20 mL NaOH, the suspension was stirred for 24 h on a magnetic stirrer. The suspension was transferred into the reaction flask. The iron pipe adapted as the furnace was packed with iron filings and pre-heated for 10 min (to increase heating efficiency of the apparatus), after which 40 mL of dry acetone was distilled. This process generated the ketene that was used for acetylation. The mixture was