Enhanced mechanical properties of polyurethane composite coatings through nanosilica addition

Abstract

Tin rich surfaces inside Pb-free electronics are more prone to tin whisker growth, thereby resulting in electrical failure of components. Conformal polyurethane (PU) coatings, which can be used as a mitigation strategy for such whisker growth, were investigated in this study. Nanoparticles of silica (~20 nm in diameter) were added via liquid suspension to the PU resin to improve its mechanical properties. Four compositions of functionalized nanosilica suspensions, 10 wt.%, 20 wt.%, 30 wt.% and 50 wt.% (corresponding to the solid silica weight of 3.50 %, 6.74 %, 9.75 %, and 15.17 %, respectively) were evaluated to establish the relationship between microstructure developments and mechanical properties. Fourier-transform infrared spectroscopy (FTIR) and low-kV field emission scanning electron microscopy (FE-SEM) were used to examine the effects of nanosilica suspension addition to the PU resin. Mechanical properties of the coating were not only evaluated by nanoindentation for localized PU matrix properties but also by uniaxial tensile testing for composite properties. Results from both scales show that the addition of the particle suspension up to 20 wt.% (corresponding to 9.75 wt.% nanosilica) makes optimum mechanical performance consisting of good modulus, strength and ductility. This conclusion is also supported from microstructural, as well as chemical aspects of the PU coatings with the addition of nanosilica suspension.

The Synergistic Effects of Sio2 Nanoparticles and Organic Photostabilizers for Enhanced Weathering Resistance of Acrylic Polyurethane Coating

“…Nano-SiO2 is the most used among the common inorganic nanoparticles. For example, by adding nano-SiO2 into the coating formulation, the mechanical, thermal, [2,17] weathering resistance [18,19], and anticorrosion properties [20,21] of the organic coatings were significantly improved. Nano-SiO2 is also used for both super hydrophobic coatings [22][23][24][25][26] or hydrophilic coatings [27].…”

“…Remaining gloss (%) = (Gt/G0) × 100 (2) where G0 and Gt are gloss of the coating (dried at 60 °C in vacuum oven until the constant weight) before and after the aging test, respectively.…”

“…Having many advantages over other conventional polymer coatings, such as good adhesion, transparency, high gloss, and weathering resistance, acrylic polyurethane coating is used widely as a protective and decorative coating for metal structures, interior and exterior wood, and automotive paint [1,2]. Two-component acrylic polyurethane paint can be cured at room temperature through the step-growth polymerization of isocyanate groups with hydroxyl groups in the acrylic polyol resin forming crosslinked urethane.…”

A comparative study on long term stability of self-healing epoxy coating with different inorganic nanotubes as healing agent reservoirs

“…Among them, polymer coatings are found to be an effective protective strategy for metal surfaces. Inorganic nanoparticles like nanoclay [3][4][5], nano iron oxide [6], nanosilica [7,8], nano zinc oxide (ZnO) [9,10], nano aluminum phosphate [11] and carbon nanofillers like graphene [12,13], carbon black [13], multi-wall carbon nanotube (MWCNT) [13] etc. filled polymer coatings further increase the protection ability.…”

Effect of Silica Nanoparticles on Properties of Coatings Based on Acrylic Emulsion Resin

“…In there, nanosilica has been attracted of scientists as its superior properties. Hence, nanosilica has been studied and applied in a lot of hi-tech manufacturing industries such as chromatography column packing materials, adsorbents, corrosion inhibitors, photocatalysts, catalyst supports, and medicine [1,[5][6][7][8]. In presence of nanosilica, some properties of materials were significantly improved such as mechanical, electrical, thermal properties and weathering characterization [9][10].…”