Abstract
Lignocellulosic nanofibrils (LCNF) is usually isolated from biomass with concentration less than 2.0 wt%. The low concentration limited the transportation and end-use application of LCNF. Therefore, the development of concentration process and the characteristics of concentrated LCNF become desirable and important for commercial deployment of LCNF application. In this study, 1.0 wt% LCNF suspension was dewatered to solid concentration of 5.9 wt%, 16.3 wt% and 25.9 wt% by a centrifuge, respectively. The un-concentrated LCNF suspension showed obviously stable translucent and well dispersed in water, while the concentrated LCNF exhibited the gel-like behavior or “solid-like” behavior based on the concentration degree. The bundle-like fibrils were observed in the concentrated LCNF, and average diameter of concentrated LCNF became large but still less than 100 nm. The crystallinity and crystallite size of un-concentrated LCNF and concentrated LCNF were similar, and it was indicated that the morphological structure changes of LCNF mainly occurred in the amorphous region of fibrils. The concentrated LCNF films still had relatively good UV-blocking property, water absorption and oxygen permeability. The increasing basis weight of films was benefit for enhancing the surface smoothness of films and interweaves between fibrils, resulting in the tensile index and specific modulus of films increasing. In sum, the concentration process affected the morphology structure of LCNF, but the concentrated LCNF still kept relatively good properties. Concentration process of LCNF suspension may be a feasible strategy for large-scale LCNF production and storage.