Nanoclay enhancement of flexural properties and water uptake resistance of glass fiber-reinforced epoxy composites at different temperatures

Abstract

In this study, glass fiber-reinforced epoxy-nanoclay composite plates, with I.30E clay contents ranging between 0 and 5 wt.%, were manufactured by hand layup with hot pressing. Flexural strength of unexposed fiber-reinforced epoxy-nanoclay reached an optimum improvement of 11% for 1.5 wt.%. Scanning electron microscope analysis showed that at this clay loading, better interfacial adhesion of clay with glass fibers was achieved. At higher clay loadings, clay agglomeration and presence micro-voids led to less strength improvement. The maximum water uptake was found to decrease with increasing clay loading and moisture diffusion at 80℃ was about 80% higher than that at room temperature. Post exposure flexural tests revealed a behavior similar to that of unexposed samples with nanoclay loading of 1.5 wt.% leading to optimal flexural properties. Exposure to moisture resulted in degradation of fiber-reinforced epoxy-nanoclay flexural properties with about 36% reduction in strength for 80℃ and 8% for room temperature.

Effects of Nanoclay on Mechanical and Dynamic Mechanical Properties of Bamboo/Kenaf Reinforced Epoxy Hybrid Composites

“…Additionally, the intrinsic property of clay (high moduli) provides an excellent compression property, leading ultimately to the increase in flexural properties. Rafiq et al [ 33 , 34 ] also reported that strong interfacial bonding between reinforcement (glass fibers and organically-modified nanoclay) and epoxy matrix exhibit higher flexural properties. However, unmodified MMT and HNT are intrinsically hydrophilic and unable to disperse well in a non-polar polymer matrix.…”

Nanoclay and Water Uptake Effects on Mechanical Properties of Unsaturated Polyester

“…As can be seen in Figure 12, the water weight gain decreases linearly with clay content. The Journal of Nanomaterials improvement in water uptake resistance is mainly attributed to the high aspect ratio of nanoclay, which creates tortious paths for the water molecules [6][7][8][9]21]. As mentioned above, the linear trend of weight gain percentage over square root of time, during the first few days of immersion, was an indication that the water uptake behavior is diffusion controlled.…”

“…This is because, at higher clay loading, the probability of clay particle agglomeration becomes higher, and hence, these clay clusters create stress raisers that decrease the tensile strength. Al-Qadhi et al [21] and Rafiq and Merah [7] have observed clay clusters and microvoids, for high clay loadings, at which cracks have initiated. Clay agglomeration and air bubbles happen because of the increase in the viscosity of the mixture at high clay loadings making the formation of exfoliated/disorder intercalated structure a difficult task due to inadequate diffusion of polyester chains between the nanoclay platelets.…”

“…Moreover, exposure of polymers to moisture for long periods is seen to degrade their glass transition temperature (T g ) and mechanical properties. The degradation takes place because of water absorption by the resin, which plasticizes the matrix and weakens the bonded area between the matrix and nanosilicate platelets [7][8][9]. Alamri and Low [8] found that the flexural strength and modulus of epoxy-based nanoclay composites decreased due to the water absorption.…”

Hygrothermal chamber aging effect on mechanical behavior and morphology of glass fiber-epoxy-nanoclay composites

“…From figure 6(c), it is evident that the failure of the specimen is due to the poor fibermatrix interface because of matrix degradation under the aging condition. Figures 6(c)-(f) exhibit that the failure of the aged specimen is due to crazing, micro-cracking, cracking, and flaking of the matrix material [44,45].…”