AN EXPERIMENTAL STUDY ON CRACK PROPAGATION IN GREEN COMPOSITES MADE FROM CELLULOSE NANOFIBERS AND EPOXY

摘要

The current examples of natural-fiber based polymer composites, because of theirbiobased and biodegradable properties, offer an alternative as a ‘green' material available forautomotive and other engineering applications. However such composites suffer from lowstrength and fatigue properties compared to the carbon- or glass-fiber based polymer composites.Cellulose nanofibers (cnfs), a new type of nanofibers made entirely from cellulose molecules,have very high mechanical properties compared to other natural fibers, even approaching that ofinorganic reinforcing fibers. The composites made from cellulose nanofiber films are likely tohave very good strength compared to other kinds of biocomposites. However such an assertionabout the mechanical properties of composites made from CNF films is yet to be investigatedthrough experiments.This paper presents the results from a crack-propagation test conducted using a doublecantilever beam made using two types of resins and reinforcements. The resins used were atraditional epoxy and a bio-based epoxy. For reinforcement, cellulose nanofiber (CNF) filmswere used. The samples were tested against a reference case made from fiberglass to study andcompare crack propagation patterns in the composites. Various crack resistance characteristicsare observed in the two systems. The study shows the need to investigate methods for improvingthe fracture toughness of polymer composites fabricated using CNF films.