Increased Interface Strength in Carbon Fiber Composites through a ZnO Nanowire Interphase

Abstract

One of the most important factors in the design of a fiber reinforced composite is the quality of the fiber/matrix interface. Recently carbon nanotubes and silicon carbide whiskers have been used to enhance the interfacial properties of composites; however, the high growth temperature degrade the fiber strength and significantly reduce the composite's in‐plane properties. Here, a novel method for enhancing the fiber/matrix interfacial strength that does not degrade the mechanical properties of the fiber is demonstrated. The composite is fabricated using low‐temperature solution‐based growth of ZnO nanowires on the surface of the reinforcing fiber. Experimental testing shows the growth does not adversely affect fiber strength, interfacial shear strength can be significantly increased by 113%, and the lamina shear strength and modulus can be increased by 37.8% and 38.8%, respectively. This novel interface could also provide embedded functionality through the piezoelectric and semiconductive properties of ZnO.

Recent advances in fiber/matrix interphase engineering for polymer composites

“…The major benefits are: no or less reduction of the substrate fiber tensile properties, growth at relatively low temperature, and possibility of achieving multifunctionality. In fact, ZnO display piezoelectric and semiconductor properties, which may be exploited in advanced composites for sensing applications [80].…”

Interaction of ZnO Nanowires with Carbon Fibers for Hierarchical Composites with High Interfacial Strength

“…The number of fragments is directly related to the interfacial shear strength and is shown to significantly increase in Figure 1. The interfacial shear strength can be computed from the average fragment length and was observed to increase from 15.87 MPa to 33.87 MPa 32 or by 113%. The increase is attributed to increased surface area, mechanical interlocking and a gradient of mechanical properties between the dissimilar materials.…”

“…ZnO nanowire arrays were grown on functionalized aramid fibers through the same procedure used with carbon fibers. 32,[35][36][37][38] To prepare single fiber fragmentation samples, single aramid fibers were placed in a silicone rubber mold (3120 RTV; Dow Corning, Midland, MI) and preloaded to 15 g, for the same reason discussed before. The molds were then filled with a 100:16.9 mixture of Epon 862/Epikure 9553 (Hexion, Houston, TX) and gelled for 1 h. The molds were heated in an oven to 100°C for 1 h, followed by 1 h at 160°C.…”

“…32,37,38 Single fiber segmentation testing was used to evaluate the interfacial shear strength of the fibers. The specimens for this test were fabricated by suspending a single filament of carbon fiber across a silicon mold that was infiltrated with a composites grade epoxy (EPON 862 resin and 9554 hardener from Hexion Specialty Chemicals (Houston, TX) blended at a resin to hardener weight ratio of 100:16.9).…”

“…There is much evidence that whiskerization can be an extremely effective tool for tailoring the interface of a composite, if the challenges pertaining the fiber tensile strength are overcome. Recently, Lin et al 32 grew vertically aligned ZnO nanowire arrays on the surface of carbon fibers and showed the technique offered promise as a whiskerization material. The nanowire arrays were grown on the fiber surface through a low temperature (<90°C) aqueous solution process that entirely preserves the fiber strength.…”