Characterization of Interface Properties of Clay Nanoplatelet-Filled Epoxy Resin and Carbon Fiber by Single Fiber Composite Technique

Abstract

The interfacial properties between carbon fiber and blend of diglycidyl ether of bisphenol A and polyglycol diglycidyl ether based epoxy resins containing different loadings (0–2.5 wt%) of surface modified montmorillonite clay — Nanomer 1.30E (nanoplatelets) — were studied using single fiber composite (SFC) technique. Carbon fibers were also treated with ethylene/ammonia polymerizing plasma to obtain a coating containing amino groups. Young's modulus and tensile strength of the nanoplatelet-filled epoxy resin (nanocomposite) increased with nanoplatelet loading up to 1.5% and decreased thereafter. The fracture strain decreased steadily with the nanoplatelet loading. The interfacial shear strength (IFSS) was found to increase with increase in nanoplatelet loading up to 1.5% but decreased thereafter for higher loadings, following the trend observed for the Young's modulus. Plasma-treated fibers showed significant increase in IFSS compared to untreated fiber for all resins, with or without nanoplatelets. SFC with plasma-treated fibers showed no noticeable crack propagation patterns as were seen in the SFC of untreated fibers. Transmission electron microscopy (TEM) used to characterize the nanoplatelet exfoliation and dispersion in the nanocomposties showed better dispersion in 1.5% nanoplatelet-loaded nanocomposites as compared to other compositions under investigation.