Mode I interlaminar fracture behavior and mechanical properties of CFRPs with nanoclay-filled epoxy matrix

Abstract

The Mechanical properties and fracture behavior of nanocomposites and carbon fiber composites (CFRPs) containing organoclay in the epoxy matrix have been investigated. Morphological studies using TEM and XRD revealed that the clay particles within the epoxy resin were intercalated or orderly exfoliated. The organoclay brought about a significant improvement in flexural modulus, especially in the first few wt% of loading, and the improvement of flexural modulus was at the expense of a reduction in flexural strength. The quasi-static fracture toughness increased, whereas the impact fracture toughness dropped sharply with increasing the clay content.Flexural properties of CFRPs containing organoclay modified epoxy matrix generally followed the trend similar to the epoxy nanocomposite although the variation was much smaller for the CFRPs. Both the initiation and propagation values of model I interlaminar fracture toughness of CFRP composites increased with increasing clay concentration. In particular, the propagation fracture toughness almost doubled with 7wt% clay loading. A strong correlation was established between the fracture toughness of organoclay-modified epoxy matrix and the CFRP composite interlaminar fracture toughness.

Environmental degradation of epoxy-organoclay nanocomposites due to UV exposure: Part II residual mechanical properties

“…Both materials exhibited a distinctively smooth top layer after UV exposure, suggesting brittle fracture caused by UV embrittlement with limited plastic deformation. The bulk of the materials displayed rough surface, resembling the fracture surfaces of both materials studied previously [15]. The smooth top layer was absent in the specimens without UV exposure, partly confirming our assumption that its thickness is a measure of the degradation due to UV radicals.…”

Effects of silane functionalization on the properties of carbon nanotube/epoxy nanocomposites

“…At higher CNT contents (0.25-0.5 wt%, Fig. 9(c) and (d)), these river markings became shorter and round-ended, similar to those observed in nanocomposites reinforced with high contents of nanoclay particles [15]. It appears that the increasing number of river markings roughly corresponds to the number of isolated, well-dispersed CNTs, which forced the cracks to propagate bypassing the CNTs and taking a long path.…”

Water absorption of epoxy/glass fiber/organo-montmorillonite nanocomposites

“…The absence of basal reflection in nanocomposites indicates good exfoliation of silicate platelets in epoxy matrix. The formation of exfoliation or intercalation of silicate platelets is due to the reaction of OMMT with amine hardener [13]. Ratna et al [14] also reported that the absence of d 100 peak in the X-ray spectrum of all binary and ternary epoxy/layered silicate systems indicates exfoliation of clay.…”