Acetylation reaction conditions. Softwood kraft and softwood kraft CNF nano-paper handsheets were cut to either 5 × 5 or 10 × 10 cm 2 . The sheets were soaked in different vol% compositions of acetic anhydride and pyridine . They were then removed from the solutions and placed individually into appropriately sized plastic Petri dishes. A small reservoir of the acetylation mixtures was placed in the corner of the Petri dish to maintain a positive atmosphere of acetylating mixture, to avoid drying of the sheets. The Petri dishes were topped with lids and thoroughly sealed with teflon tape. These were placed in a laboratory oven at 80 °C for 1 to 9 days. The reactions were quenched by soaking the sheets in a water bath for 18 hr (*2), followed by drying the wet sheets in a fume hood, in open containers.