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Composites from northern red oak (Quercus robur) leaves and plant oil-based resins



Composite materials were successfully made out of plant oil-based resin and northern red oak (Quercus robur) leaves collected in the fall. The viscosities of the bio-based resins (MAESO and MAELO) were suited to high temperature resin transfer molding (RTM) and vacuum-assisted resin transfer molding (VARTM) processing. The leaves have a waxy epidermal surface layer that needs to be dewaxed prior to use in a composite part. We used different treatments (such as benzene–ethanol, boiling water, and strong detergent) to dewax the leaves; all three methods seem to give good results; but boiling water and strong detergent were considered the best treatments for the dewaxing of leaves and boiling water was considered the greenest dewaxing method. The compatibility between the resin and the leaves was improved with a silane treatment which resulted in composites with higher mechanical stiffness than the resin itself. With 10 wt % leaves, we obtained an improvement in the composite modulus of about 14% from which we could estimate the leaf modulus at about 5.3 GPa. An alternative method to produce biocomposites from leaves without the need for silane treatments consists in carbonizing the leaves first at 215°C for 12 h, and then at 450°C for 1 h. The composites made with leaves and bioresins derived from functionalized triglycerides have the potential for use in high volume applications with low costs such as housing, construction, civil infrastructure, toys, and furniture. The use of leaves as a biocomposite filler has several advantages including (a) reduced cost, (b) improved properties of the resin, (c) composites with high bio content, (d) removal of a waste material with subsequent prevention of burning with attendant health hazards, and (e) interesting design aesthetics for interior and exterior decoration. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2013