Ultrathin wood laminae-polyvinyl alcohol biodegradable composites

Novel polyvinyl alcohol (PVOH) based biodegradable composites were prepared by a hand lay-up process using ultrathin beech laminae cut by a specialized planer machine, and the resulting materials were thermo-mechanically characterized. Density measured showed how the adopted procedure led to laminates having a high porosity degree (about 50% by volume) and an elevated wood concentration (about 80% by weight). In fact, because the wood fibers were perfectly cut (not pressed and abraded), wood porosity was partially filled by the PVOH resin, as documented by field emission scanning electron microscope (FESEM) micrographs. The occlusion of wood porosity by the PVOH matrix resulted to be beneficial for the tensile mechanical properties of the composites. In fact, quasi-static tensile tests and DMTA analysis revealed how the stiffness (E, E0) and strength (rb) values of the composites both along longitudinal and transversal directions were considerably higher than those of the constituents. On the other hand, the values of the specific energy adsorbed under impact conditions by the composites samples were rather low, if compared to the neat matrix.