Effect of retention rate of fluorescent cellulose nanofibrils on paper properties and structure

In this work, we report a new characterization method using fluorescent cellulose nanofibrils to analyze retention and loss rates in the papermaking process. Cellulose nanofibrils (CNF) were isolated from chemical pulp by enzymatic pretreatment and used as a strengthening additive in sheet forming. The aim of this paper was to investigate its effects on flocculation, retention and loss rate and the physical and mechanical properties. CNF was subjected to fluorescent labeling with RBITC (Rhodamine B isothiocyanate), and the retention of fluorescent cellulose nanofibrils (FCNF) was analyzed by elemental analysis and fluorescence intensity. The retention and loss rate of the FCNF decreased with increasing the addition of FCNF. Laser Confocal Scanning Microscopy (LCSM) and Scanning Electron Microscope (SEM) images confirmed that FCNF can be evenly distributed in the paper. A thorough investigation of the relation between the retention rate and papersheet performance was conducted.