Nanoinduced morphology and enhanced properties of epoxy containing tungsten disulfide nanoparticles

Closed‐cage (fullerene‐like) nanoparticles (NPs) of WS₂ 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/WS₂ nanocomposites were studied. The morphology of the epoxy nanocomposites was induced by controlled WS₂ surface chemistry. The WS₂ 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 WS₂ 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 WS₂ compared with the neat epoxy. Modeling of the nodular morphology enabled the determination of optimal concentration of the WS₂ 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. POLYM. ENG. SCI., 53:2624–2632, 2013. © 2013 Society of Plastics Engineers