Using fibre property measurements to predict the tensile index of microfibrillated cellulose nanopaper

A wide variety of wood and non-wood cellulosic fibre sources were used as a feed to produce microfibrillated cellulose (MFC) using a grinding process. Nanopaper was formed using this product, and the tensile index was measured. The hemicellulose content of the feed fibres was measured, and was found to correlate with the production of finer microfibrils and a higher MFC tensile strength. The correlation with tensile strength was improved by the inclusion of a measurement of the MFC particle lengths as measured by a fibre image analyser, with the resulting relation fitting a modified Page Equation. It was hypothesised that the frequency of flaws in the feed fibre cross-section influences the length of the MFC particles produced, and so the zero-span tensile index of the fibres was measured as a proxy for this since it forces cross-sectional fibre breakage. The fibre zero-span tensile index was found to correlate with MFC particle length and so was used in its place in the equation. The resultant equation can predict MFC tensile strength from zero-span tensile index and hemicellulose content measurements of cellulosic fibres and can aid in optimising feedstock selection for mechanical MFC production processes.