Achieving outstanding mechanical/bonding performances by epoxy nanocomposite as concrete–steel rebar adhesive using silane modification of nano SiO2

Abstract

Anchoring steel rebar in concrete structures is a common method in the building and construction industry. This research focuses on improving the mechanical/bonding properties of the prepared epoxy nanocomposite adhesive using surface treatment of SiO2 nano fillers by glycidoxypropyltrimethoxysilane (GPTMS). For this purpose, the nano silica particles were silanized via a facile sol–gel method at silane concentrations of 1, 5, 10 and 20X (i.e. X is stoichiometric silane concentration). The nanoparticles were characterized carefully by FTIR, TGA, XRD and XPS techniques. It was found that the highest GPTMS grafting ratio was obtained at silane concentration of 10X. The pure and silanized nanoparticles were added to a two-pack epoxy resin and were compared for tensile and compressive properties. It was found that surface modification of nano silica caused improvement in the strength, modulus, compressive strength and compressive modulus by 56, 81, 200 and 66% compared to the pristine epoxy adhesive and also 70, 20, 17 and 21% compared to the pure nano silica containing adhesive. It also caused 40 and 25% improvement in the pullout strength, 33 and 18% enhancement in the pullout displacement and 130 and 50% in adhesion energy compared to the pristine and raw silica-containing adhesives, respectively.

Synthesis of colloidal silica nanofluid and assessment of its impact on interfacial tension (IFT) and wettability for enhanced oil recovery (EOR)

“…Besides, bands between 1630 and 1640 cm −1 are pertinent to the bending vibration of the –OH group. In addition, bands from 417 to 475 cm −1 belong to tensile modes of Si–O–Si 31 . Bands between 2058 and 2095 cm −1 belong to the chemical adsorption of water.…”

Reduction of injection molded silica glass defects and enhancement of glass quality via water debinding

“…This zeta potential value decreases to À17.73 mV for the silica nanoparticles in the brown parts that are prepared without water debinding, indicating the decrease in the oxygen vacancies at the surface of silica nanoparticles. 36,48 However, the water debinding duration strongly contributes to the increase in the negative surface charge of silica nanoparticles (i.e., increase in the oxygen vacancies). For instance, as the water debinding duration prolongs from 0 to 3 h, the absolute value of zeta potential of the brown parts increases from À17.73 mV to À24.43 mV and the surface zeta potential is saturated when the water debinding time is 4 h (Fig.…”

“…This zeta potential value decreases to −17.73 mV for the silica nanoparticles in the brown parts that are prepared without water debinding, indicating the decrease in the oxygen vacancies at the surface of silica nanoparticles. 36,48 However, the water debinding duration strongly contributes to the increase in the negative surface charge of silica nanoparticles ( i.e. , increase in the oxygen vacancies).…”

Chemical/photochemical functionalization of polyethylene terephthalate fabric: effects on mechanical properties and bonding to nitrile rubber

“…This parameter was calculated using TGA test data and Eq. ( 2 ), in the way that for each water molecule separated from the surface in the specified temperature range, two surface −OH groups are separated 41 , 42 . …”