The synergy between cellulose nanofibrils and calcium carbonate in a hybrid composite system

Abstract

The aim of this study is to evaluate the properties of bio-based composite films prepared from nano/microfibrillated cellulose and calcium carbonate. In addition, a preliminary assessment to investigate the possibility of using such a system as a binder for lignocellulosic materials was conducted. Microfibrillated cellulose/calcium carbonate composite (50:50) produced by FiberLean® Technologies UK (hereafter referred to as FLC) was used as the source of calcium carbonate. The three tested composite systems were pure CNF films and films containing 25 wt% and 50 wt% calcium carbonate. The morphology of the films assessed by scanning electron microscopy and energy-dispersive spectroscopy demonstrated the uniform distribution of calcium carbonate on the film surface and in the z-direction. The mechanical properties showed no significant difference between pure CNF films and films containing 25 wt% calcium carbonate (as opposed to films prepared with 50 wt% mineral load). Lap shear testing showed no significant difference between the three tested samples indicating that the presence of calcium carbonate particles did not inhibit the binding properties of CNFs. The presence of calcium carbonate increased the thermal stability of the films. During dewatering analysis, a 25 wt% calcium carbonate load resulted in a maximized retention and a consistent dewatering behavior. At 50 wt% mineral load, the maximum retention obtained was 94% and inconsistent dewatering pattern was observed.