“Brick-and-Mortar” Nanostructured Interphase for Glass-Fiber-Reinforced Polymer Composites

Abstract

The fiber-matrix interface plays a critical role in determining composite mechanical properties. While a strong interface tends to provide high strength, a weak interface enables extensive debonding, leading to a high degree of energy absorption. Balancing these conflicting requirements by engineering composite interfaces to improve strength and toughness simultaneously still remains a great challenge. Here, a nanostructured fiber coating was realized to manifest the critical characteristics of natural nacre, at a reduced length scale, consistent with the surface curvature of fibers. The new interphase contains a high proportion (∼90 wt %) of well-aligned inorganic platelets embedded in a polymer; the window of suitable platelet dimensions is very narrow, with an optimized platelet width and thickness of about 130 and 13 nm, respectively. An anisotropic, nanostructured coating was uniformly and conformally deposited onto a large number of 9 μm diameter glass fibers, simultaneously, using self-limiting layer-by-layer assembly (LbL); this parallel approach demonstrates a promising strategy to exploit LbL methods at scale. The resulting nanocomposite interphase, primarily loaded in shear, provides new mechanisms for stress dissipation and plastic deformation. The energy released by fiber breakage in tension appear to spread and dissipate within the nanostructured interphase, accompanied by stable fiber slippage, while the interfacial strength was improved up to 30%.

Synergistic Strengthening and Toughening the Interphase of Composites by Constructing Alternating “Rigid‐and‐Soft” Structure on Carbon Fiber Surface

“…Interfaces 2019, 6, 1900970 frictional sliding, plastic deformation, and viscoplastic energy dissipation, [8] which is similar to the toughening mechanism of nacre-like biological materials. Mater.…”

“…Different inorganic materials, including graphene, [10] layered double hydroxide (LDH), [11] nanoclay, [12] man-made CaCO 3 , [13] Al 2 O 3 , [14] carbon nanotube (CNT), [15] and TiO 2 , [16] have been employed as "bricks" in fabrication of analogous nacre film materials. [1,6,17] To manifest the critical characteristics of natural nacre, a LDH/poly(sodium-4-styrenesulfonate) nanostructured coating over the surface of glass fiber by LbL was reported by Luca et al, [8] which increased the interfacial shear strength (IFSS) and debonding toughness by 30% and 162%. Inspired by these, whether construction of an composite interphase with nacre-like layered structure can simultaneously enhance the composites' interfacial strength and toughness?…”

“…[1,6,17] To manifest the critical characteristics of natural nacre, a LDH/poly(sodium-4-styrenesulfonate) nanostructured coating over the surface of glass fiber by LbL was reported by Luca et al, [8] which increased the interfacial shear strength (IFSS) and debonding toughness by 30% and 162%. [1,6,17] To manifest the critical characteristics of natural nacre, a LDH/poly(sodium-4-styrenesulfonate) nanostructured coating over the surface of glass fiber by LbL was reported by Luca et al, [8] which increased the interfacial shear strength (IFSS) and debonding toughness by 30% and 162%.…”

Increasing carbon fiber composite strength with a nanostructured “brick-and-mortar” interphase

“…A short 5 min plasma treatment was used to increase surface charge whilst retaining a low surface roughness needed to form well-ordered, nanostructured LbL deposits. Disordered versions of these ''brick-and-mortar'' nanostructures on glass substrates are known not to allow for platelet pull-out or effective crack deflection, 37,38 likely limiting improvements in composite tensile properties. The measured z-potentials showed that all fibers were negatively charged over the entire pH range.…”

“…We have previously demonstrated the efficacy of this system on flat substrates as well as at the interphase of single glass fiber composites, showing that the correct phase proportions and geometry enabled the mechanical performance and toughening mechanisms of nacre to be reproduced, but at a much smaller length scale. 37,38 Here, we report the deposition of this nanoscaled nacre mimic around structural carbon fibers. Due to its self-limiting nature, the Layer-by-Layer (LbL) method provides a convenient route to generate a well-ordered coating on multiple fibers simultaneously.…”