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    In-situ preparation of halloysite nanotube-epoxy thermoset nanocomposites via light-induced cationic polymerization
    (Elsevier Ltd, 2021) Bekin Acar, Seda; Çiftci, Mustafa; Bouharras, Fatima Ezzahra; Raihane, Mustapha; Tasdelen, Mehmet Atilla
    In the present study, homogeneous mixtures of halloysite nanotubes (HNTs)-epoxy nanocomposites are prepared through chemical treatments. Naturally present halloysite nanotubes (HNT) are primarily modified by 3-(glycidyloxypropyl)trimethoxysilane and subsequently utilized as nanofillers in a mixture of bisphenol A diglycidyl ether and trimethylolpropane triglycidyl ether by varying weight % of modified HNT from 0 to 8%. Photoinitiated cationic crosslinking polymerization of this mixture facilitates the in-situ preparation of HNT/thermoset nanocomposites at room temperature. The covalent attachment of HNT in the thermoset matrix has been confirmed by monitoring the characteristic signals of the mixture, nanofiller, neat thermoset, and final nanocomposite using fourier transformed infrared (FT-IR) spectroscopy. Furthermore, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses proved the existence and distribution of HNT in the thermoset nanocomposites. Indeed, a combination of agglomerated/non-agglomerated HNTs in the thermoset matrix is also determined. On the other hand, mechanical properties of nanocomposites are significantly improved with increase in HNT loading up to 4% ratio. Adding 4% of modified HNT into epoxy increased its tensile strength and elasticity modulus by 6.9 times and 2.3 times than the corresponding neat epoxy thermoset, respectively, without scarifying thermal stability. Therefore, the HNT/epoxy thermoset nanocomposites are suitable candidates for various applications as an alternative of expensive carbon nanotube containing analogues.
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    POSS-based hybrid nanocomposites
    (Elsevier, 2021) Bekin Acar, Seda; Özdoğan, Reyhan; Tasdelen, Mehmet Atilla
    Hybrid nanocomposites have attracted considerable attention since they could combine superior advantages of two or more nano-fillers. Owing to the multifunctional properties of nano-fillers, they have emerged as a promising new class of materials for high-tech applications. Various nano-fillers including clay, carbon nanotubes, graphene, metal oxides, and polyoctahedral oligomeric silsesquioxane (POSS) have been extensively used for the preparation of hybrid nanocomposites. Among them, POSS derivatives have received significant attention due to their precisely defined hybrid structures with a variety of functional groups helping to chemically or physically combine with other nano-fillers to enhance stiffness performance and reduce the electrical conductivity of the material. In this chapter, hybrid nanocomposites prepared by POSS with other one-dimensional nano-clays, two-dimensional graphene and graphene oxides, carbon nanotubes and boron nitrides, and three-dimensional fullerenes, gold, silver, and iron nanoparticles, and titanium and silicon dioxides are explored in detail.