Non-agglomeration and dispersion of silica nanoparticles in polymers and their interfacial interactions to polymer matrix are the most important factors that influence nanocomposites performance. In this work, vinyltriethoxysilane (VTES) as a low VOC emission coupling agent was used for surface modification of silica nanoparticles to prepare better dispersion in nitrile rubber (NBR) and improve its interfacial interactions to silica nanoparticles. The results of X-ray photoelectron spectroscopy, thermogravimetric analysis and Fourier transform infra-red spectroscopy demonstrated successful attachment of VTES molecules on the surface of silica nanoparticles. Dispersion of the modified silica nanoparticles in NBR matrix was studied using field emission scanning electron microscopy and rubber process analysis. Results demonstrated that VTES significantly improved dispersion of nanoparticles in rubbery matrix. The bound rubber content showed that VTES effectively built a bridge between the silica nanoparticles and the rubber matrix that led to promising mechanical performances and strong interfacial interactions. Effect of nanoparticle content on the mechanical performances (static/dynamic) of the NBR was evaluated. It was found that higher modulus and reinforcement indices was obtained at 3 and 5 wt% of nanoparticles. Moreover, these composites had extremely low rolling resistance, the best wet skid resistance and the lowest Heat-Build up.
To prepare a nanocomposite adhesive based on nitrile
rubber (NBR)
with excellent mechanical/anticorrosion properties, cerium oxide (CeO2) nanoparticles were grafted with bis-[3-(triethoxysilyl)propyl]tetrasulfide
silane (TESPT) at different concentrations (i.e., 1, 5, 10, and 20
times the stoichiometric content). The surface-modified nanoparticles
were characterized by Fourier transform infrared spectroscopy (FTIR),
ζ-potential, X-ray photoelectron spectroscopy (XPS), thermogravimetric
analysis (TGA), and field emission scanning electron microscopy (FE-SEM)
techniques. The results showed that the steaming process resulted
in an increase in the grafting ratio (R
g) by 2.35 times. Pure and modified cerium oxide nanoparticles were
added at 1.5, 4.5, and 7.5 wt % to a mixture of a phenolic resin and
NBR compound to prepare adhesive samples. The prepared adhesives were
evaluated for curing behavior and thermomechanical properties. The
morphology of the adhesives was also characterized using SEM analysis.
The bonding of adhesives to steel plates was measured by a cathodic
disbonding test. The adhesive-coated steel plates were evaluated for
anticorrosion performances using a salt spray test. It was found that
surface-modified hydrothermally steamed CeO2 nanoparticles
that had the highest silane grafting ratio enhanced the anticorrosion
properties and cathodic disbonding of NBR-based adhesives. The curing
rate index (CRI) and crosslinking of the NBR compound were enhanced
using the modified and steamed nanoparticles. This also improved the
interfacial interactions between rubber chains and nanoparticle surface,
resulting in a 6 °C increase in the glass-transition temperature
(T
g) of NBR compared to the pristine rubber.
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