Superior non-woven sheet forming characteristics of low-density cationic polymer-cellulose nanofibre colloids
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This work examines the addition of cationic polymers, cationic polyacrylamide (CPAM) and polyamide–amine–epichlorohydrin (PAE), to cellulose nanofibres to produce superior forming characteristics. The addition of 2 mg of high MW CPAM/g of nanofibres halved the drainage time to under 1 min at 0.1 wt% solids content due to increasing the floc size and the fibre forming a bulky and porous filter medium during drainage. The more open structure created in the wet state was partially preserved during the drying process, reducing the sheet density from 760 to 680 kg/m3, at the highest level of polymer addition. The addition of CPAM resulted in significant additional bridging between nanofibres, which then substantially increased the non-uniformity of the filter medium. PAE addition at 10 mg/g of micro fibrillated cellulose (MFC), also reduced drainage time, while increasing retention, but without changing the sheet uniformity. Wet strength increased continuously with PAE addition level, reaching 31.6 kN m/kg at the highest level of 20 mg of PAE/g of MFC.
KeywordsCellulose nanofibres CPAM PAE Strength Sheet preparation Gel point
The authors would like to acknowledge the facilities used at the Monash Center for Electron Microscopy and Xi-Ya Fang for her assistance on SEM. We would also like to acknowledge Jielong Su for experimental help and for providing the softwood sheet, as well as Scot Sharman and Hui Hui for providing the hardwood sheet. We would like thank Scot Sharman for providing information about PAE charge density. We would like to thank Jane Moodie for her assistance on manuscript preparation. We acknowledge the financial support of the Australian Research Council, Nopco Australasia, and Visy through Linkage Project Grants LP0990526. Swambabu Varanasi thanks Monash University for a MGS and FEIPRS Scholarship.
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