Optimized mechanical and impact performance of high strength tempo oxidized cellulose nanofibril (TOCNF)—epoxy laminates

Abstract

In this work, TEMPO cellulose nano bril (TOCNF) laminates were fabricated using a layup method. Two different TOCNF layers were tested, a neat TOCNF and a TOCNF with polyvinyl alcohol (PVA) strengthening aid with four different epoxy formulations as interlayers for the laminates. Flexural testing showed a correlation between the presence of stronger layers (TOCNF + PVA) in the laminate with a higher exural strength, bending modulus, and work of failure. Different modes of fracture within the laminates occurred based on epoxy type. A stiffer epoxy generated a reduced mechanical response and substantial interlayer damage. On the other hand, a more ductile epoxy increased the WOF of the laminates, inducing a higher delamination at the interface. The addition of a silane coupling agent (APTES) resulted in a higher compatibility between the TOCNF and epoxy, generating an increased ultimate tensile strength (UTS) and a decreased energy to rupture associated with the reduction of crack digression mechanisms in the system. In general, laminates with stronger TOCNF layers (TOCNF + PVA) and increased adhesion (APTES), showed a exural strength increase of 61%, a bending modulus increase of 80% and the same WOF when compared with the original laminates. Finally, impact testing of TOCNF materials was performed for the rst time in literature, the speci c energy to rupture of laminates was comparable to those achieved by acrylic and borosilicate glass, while maintaining a higher or similar speci c strength to glass. Laminates showed good transparency and low haziness.

Performance and application study of silane coupling agent (KH550) modified wood fiber‐fly ash cenosphere/epoxy resin composites

“…After performing compression performance tests on six sets of specimens, the obtained stress‐strain curves with yield strength, Figure 3. The grafting modification of the filler surface significantly increased the mean stress plateau value [35–38]. Also comparing specimens B and E, the filler modification also significantly reduced the stress reduction from material cracking.…”