The effect of different additives on the properties of handsheet prepared from office waste paper

This study was performed in order to compare the independent and combined effects of four types of additives including cellulose nanofibers, cationic polyacrylamide, cationic starch, and imported long fiber pulp in the handsheet prepared from office waste paper. Independent treatments included the addition of 15% long fiber pulp, 3% cellulose nanofibers, 0.75% cationic starch and 0.07% cationic polyacrylamide. Combination treatments included firstly addition of 0.75% starch and then 3% cellulose nanofibers, and also 0.07% cationic polyacrylamide and 3% cellulose nanofibers. Handsheets with grammage of 60 g/m2 were made from seven furnishes and finally the physical, mechanical and microscopic structures of the handsheet were investigated. The results showed that addition of long fiber pulp, cationic starch, cationic polyacrylamide and cellulose nanofibers slightly reduced the density of handsheets compared with the control. The highest surface smoothness was achieved using combined treatments of cellulose nanofibers, which could improve the printability of the paper, but decreasing the air permeability and reducing the water drainage of the sheet by adding cellulose nanofibers could cause problems on paper and printing machines. Tensile, burst and tear indices of handsheets had the highest increase by the addition of 15% long fiber pulp, and then using 0.75% cationic starch improved the strength compared with other treatments. Electron microscopy images showed a relative reduction of porosity in the handsheets made from cellulose nanofibers, which could have negative effects on water drainage of recycled pulp.