Stereolithography-fabricated polymer composites reinforced with Agave angustifolia Haw bagasse fibers and MWCNTs for PEMFC bipolar plates

Abstract

The present work investigates novel composites fabricated via stereolithography (SLA) additive manufacturing, consisting of an acrylonitrile butadiene styrene (ABS)-like photopolymer matrix reinforced with Agave angustifolia Haw bagasse fibers (AFs) and multi-walled carbon nanotubes (MWCNTs), with a focus on evaluating their potential application as bipolar plates (BPs) in proton exchange membrane fuel cells (PEMFCs). Initially, ABS polymer composites reinforced with AFs (1.0, 1.5, 2.0, 2.5, 3.0, 3.5, and 4.0 wt %) were explored. Afterward, MWCNTs (0.05, 0.1, and 0.2 wt %) were added to the best ABS-AFs composite to improve its mechanical and electrical properties. For the ABS-AF composites, the ABS (98 wt %)-AFs (2 wt %) composite increased tensile strength by 14 % (from 43 MPa to 49 MPa) and flexural strength by 15 % (from 24.0 MPa to 27.6 MPa) compared to the pristine ABS composite. For the ABS-AF-MWCNT composites, the ABS (97.9 wt %)-AFs (2 wt %)-MWCNTs (0.1 wt %) composite achieved an additional 20 % increase in tensile strength (59 MPa) and 36 % in flexural strength (37.5 MPa) compared to the ABS (98 wt %)-AFs (2 wt %) composite. For all produced composites, corrosion measurements indicated stability, with corrosion current densities ranging from 0.16 to 0.68 μA cm −2 , remaining below the U.S. Department of Energy (DOE) corrosion target (<1 μA cm −2 ) under the conditions tested. Thermogravimetric analysis showed that all composites exhibit high thermal stability, with degradation temperatures exceeding 370 °C. Scanning electron microscopy showed that the MWCNTs are individually dispersed at 0.05 wt % but form entangled agglomerates at 0.20 wt %, coinciding with the loss of flexural strength at that loading. Four-point probe measurements showed that the sheet resistance is out of range of the instrument, so the composites are electrically insulating and the DOE electrical conductivity target (>100 S cm −1 ) is not met. The results indicate that SLA is a viable route for producing AFs- and MWCNT-reinforced photopolymer composites with the mechanical properties required for BPs. However, further strategies are still required to enhance the electrical properties.