Nanoinduced morphology and enhanced properties of epoxy containing tungsten disulfide nanoparticles

Abstract

Closed-cage (fullerene-like) nanoparticles (NPs) of WS 2 are currently produced in large amounts and were investigated as additives to thermoplastics and thermosetting polymers. The nanoinduced morphology and the resulting enhanced fracture toughness of epoxy/WS 2 nanocomposites were studied. The morphology of the epoxy nanocomposites was induced by controlled WS 2 surface chemistry. The WS 2 NPs used were either untreated or chemically treated with acryloxy, which is compatible, and alkyl silane, which is incompatible, respectively, with the epoxy matrix. In the case where the acryloxy silane was used to treat the WS 2 particles, good dispersion and compatibility were obtained in the epoxy resin . Moreover, a distinct nodular morphology was induced on fracture as a result of nucleation by the compatible NPs. In the case where the alkyl silane treatment was used cavitation morphology was induced, following mechanical loading, which is the result of incompatibility with the epoxy resin. The fracture toughness results showed an increase of 70% for nanocomposites contains alkyl-treated WS 2 compared with the neat epoxy. Modeling of the nodular morphology enabled the determination of optimal concentration of the WS 2 in epoxy (0.3% by weight). Two main fracture mechanisms were observed, crack bowing around the nodular boundaries in the case of compatibility between the nanoparticle and the epoxy and particle-induced cavitation in the case of incompatibility, respectively. These results are of significant importance both for epoxy-based adhesives and fiber composites. FIG. 2. (a) SEM micrograph of fracture surface of epoxy/0.5 wt% acryloxy-treated WS 2 NPs. (b) Epoxy/ 0.5 wt% alkyl-treated WS 2 NPs.

Significance of epoxy network properties for the toughening effect of flaky and fullerene‐like WS2 nanoparticles

“…Table 2 lists the T g and fracture toughness results of the various nanocomposites. As expected, adding any kind of WS 2 NPs did not affect the T g significantly (cf. Fig.…”

“…1,2,23,24 However, changes in the manufacturing process with time or unintentional variation from batch to batch cannot be excluded. According to the manufacturer, this powder was produced by high-temperature solid-gas synthesis, the primary particles had diameters of 50 to 150 nm and they consisted of 10-100 WS 2 layers, with an interlayer spacing of 0.62 nm.…”

“…90 nm, approx. 30 m 2 /g specific surface area, nearly spherical morphology and a true density of 7.50 g/cm 2 . Thus, the size and shape are comparable to the IF-WS 2 powder, even though the crystal structure is different.…”

“…FULL PAPER improvements in the fracture toughness were obtained only for W T403 540 phr and w IF 50:50%, which is the combination for which the substantial improvements in earlier reports were obtained. 1,2 This raises the question to what extent these improvements can be generalized. Figure 10 highlights the dependency of the toughening effect on W T403 graphically.…”

“…Nanodispersed, flaky WS 2 is expected to behave somewhat similarly to IF-WS 2 when used as a nanofiller due to the similar surface chemistry and the similar primary particle size, the most significant difference being the crystal structure. However, due to their spherical shape, IF-WS 2 NPs can roll off each other, 4 so that they are potentially easier to dis- 2 NPs can be found in the related literature. [5][6][7] Much effort has been dedicated to determine the toughening effect of the NP type, morphology and functionalization, 8 but relatively little attention has been given to the significance of the properties of the neat epoxy system.…”