Mechanical, dielectric, and thermal properties of polydimethylsiloxane/polysilsesquioxane nanocomposite for sealant application

Abstract

Polysilsesquioxanes (PS) powder was synthesized from methyltrimethoxysilane and vinyltrimethoxysilane by hydrolytic condensation method in aqueous phase. The prepared PS powder was characterized using Fourier transform infrared spectroscopy, particle size, and polydispersity of the powders was determined using dynamic light scattering technique. Polydimethylsiloxane (PDMS) nanocomposites and the sealant were synthesized using different weight percentage (1-4 wt %) of PS powder and hydrophobic fumed silica. Tensile strength and thermal stability of the nanocomposites showed perceptible enhancement on increasing the filler ratio when compared to pristine PDMS composites. The surface morphology and the extent of filler dispersion were visualized from the scanning electron microscopy images. Dielectric strength of the composites also showed significant improvement on increasing the filler loading. Poly(methyl/vinyl)silsesquioxane (PMVS) (4 wt %) reinforced composites showed a considerable enrichment in properties when compared to other formulations. Adhesive strength of silicone sealant on both the alumina and mild steel substrate was studied by conducting lap shear test. PMVS-loaded nanocomposites exhibited more adhesive strength on both the substrates and hence it can be used as a sealant in electronic assemblies.

PEMFC catalyst layer modification with the addition of different amounts of PDMS polymer in order to improve water management

“…By condensing Si═OH groups with a cross‐linker, strong polymer networks are formed . PDMS has been frequently used in hydrophobic surface preparation in recent years but has never been applied to the catalyst layer of PEM fuel cell. PDMS is a polymer with high chemical resistance and hydrophobicity.…”

Investigation of Direct and Indirect Magnetoelectric Couplings in P(VDF-HFP)/CoFe2O4 Nanofiber Composite Films

“…All of the films that have high dielectric constant values in the low-frequency region decrease gradually with the increase in frequency. At low frequency, dipoles in the films have enough time to polarize, whereas at high frequency, the dipoles do not get enough time to align themselves in the direction of the applied electric field, which results in a decrease in dielectric constant and capacitance. , Figure c indicates a gradual decrease in dielectric loss with respect to increasing frequency up to 10 4 Hz and then an increase for a higher range of frequencies.…”

Molecular behavior of silicone adhesive at buried polymer interface studied by molecular dynamics simulation and sum frequency generation vibrational spectroscopy

“…[1][2][3][4][5][6][7] Due to these remarkable properties, PDMS is widely used in many applications ranging from construction and electronics, to automotive manufacturing. 4,[8][9][10][11] Compared with other adhesives, PDMS-based adhesives have significantly higher thermal stability while retaining flexibility at lower temperatures, leading to their use in many outdoor applications under extreme conditions. 12,13 Despite its extensive applications, it can be challenging to use PDMS-based adhesives to adhere to all the possible types of substrates.…”