THE IMPACT OF THE NANOFIBRILLATED-CELLULOSE ADDITION ON THE MECHANICAL PROPERTIES OF POLY(3-HYDROXYBUTYRATE)

In this paper a novel processing route for nanocomposites, based on (3-hydroxybutyrate) (PHB) and nanofibrillated cellulose (NFC), is presented. To obtain a uniform dispersion of the reinforcing filler, a PHB powder was first dispersed in water, mixed with an NFC aqueous suspension and then freeze dried to eliminate the water phase from the ensuing system. The dried batch was then extruded and added to the granulated PHB in different weight proportions. Nanocomposites with various NFC contents were subsequently produced with the injection -moulding technology. The processing limits and feasible solutions for their optimization are thoroughly described within this work. Morphological properties were investigated with FE-SEM, while mechanical properties were determined via a tensile test. SEM images showed that the PHB powder can be effectively incorporated into the mesh of cellulose nanofibrils, as clearly evident by the interlaced structure of individual fibrils with the average lateral dimensions of 69 +/- 14 nm. Improved mechanical properties and SEM observations confirmed a good interfacial adhesion and uniform distribution of the reinforcing component. Compared to the unfilled matrix (E-t = 1340 MPa; sigma(M) = 20 MPa; epsilon(b) = 2.4 %), an escalating trend in 1720 MPa) and tensile strength (sigma(M) = 26 MPa), along with decisively improved values of the elongation at break (epsilon(b) = 3.1 %), were observed nanocomposites can be produced via extrusion moulding, whereby the proportion of the reinforcing phase dictates the final material performances.