Preparation and properties of fumed silica/cyanate ester nanocomposites

Abstract

Fumed silica/bisphenol A dicyanate ester (BADCy) nanocomposites were prepared by introducing different contents of nano-sized fumed SiO 2 into the BADCy matrix. Two different average primary particle diameters of 12 and 40 nm were chosen. Dibutyltindilaurate (DBTDL) catalyst was chosen to catalyze the cyanate ester group into triazine group via cyclotrimerization reaction. The SEM micrographs indicated that the fumed SiO 2 particles were homogeneously dispersed in the poly(bisphenol A dicyanate) matrix by means of ultrasonic treatment and the addition of a coupling agent. The FTIR spectroscopy shows that, not only DBTDL catalyzes the polymerization reaction but also -OH groups of the SiO 2 particles surface help the catalyst for the complete polymerization of BADCy monomer. The thermal stability of the cured BADCy can be improved by adequate addition of fumed SiO 2 . A slight increase in the dielectric constant and dielectric loss values were identified by testing the dielectric properties of the prepared nanocomposite samples. By increasing the SiO 2 content, there was a slight increasing in the thermal conductivity values of the tested samples. The obtained results proved that the fumed silica/BADCy nanocomposites had good thermal and dielectrical properties and can be used in many applications such as in the thermal insulation field.

Effect of Nanoparticle Functionalization on the Performance of Polycyanurate/Silica Nanocomposites

“…The acidic silanol groups provide a source for these protons, as has been noted in previous studies. 17 −19,22 The comparatively basic amino groups, however, provide a proton sink that reduces the "background" level of protons available for catalysis, thus raising the cure onset temperature. Figures 5 and 6 show that both the temperature at the onset of reaction and the temperature at peak heat flow show similar behaviors as a function of nanoparticle loading.…”

“…One of the most common, and most important, of these reinforcements is silica. The properties of polycyanurate/silica composites have been investigated and reported in the literature on limited occasions. − One very important practical question has received relatively little attention (the work of Wooster et al being a notable exception): How does the nature of the silica/polycyanurate interface affect the kinetics of cyanate ester cure and the resulting polucyanurate physical properties? Untreated silica particles have an interface rich in silanol groups.…”

Silicon-containing trifunctional and tetrafunctional cyanate esters: Synthesis, cure kinetics, and network properties

“…A strategy used to provide thermooxidative protection in cyanurate polymer networks that has been explored through much recent investigation is the incorporation of silicon or siloxy moieties in the form of monomers and cocuratives, blends and modifiers, silica nanoparticles, clay nanoplatelets, or other silicon‐containing nanostructures including oligomeric silsesquioxanes . While the addition of silicon in fully oxidized form (i.e., as SiO 2 ) can provide an in‐place barrier to oxygen permeation, the use of unoxidized organosilicon moieties or partly oxidized silicates allows for the in situ generation of a protective barrier during high‐temperature oxidation or exposure to energetic forms of oxygen (such as atomic oxygen in low Earth orbit) .…”

Effects of macromolecular silane coupling agent on the mechanical properties of nano-SiO2/cyanate ester nanocomposites

“…[1][2][3][4] However, like most other thermosetting resins, the biggest shortcoming of cyanate ester resins is its brittleness. To improve the toughness, many methods have been developed to modify cyanate ester resins, such as polymer blending, 5,6 filler filling [7][8][9] and fiber reinforcing. 10 The advantage of these methods is that the fracture toughness can be improved dramatically.…”

“…17 For example, Goertzen and Kessler 18,19 investigated the effects of amount and particle size of fumed silica on the dynamic mechanical properties of 2 0 -Bis(4-cyanatophenyl)isopropylidene (BCE) resins, and the results showed that the storage moduli of the composites were increased with increasing content of fumed silica. Taha and Gao 8 investigated the effects of fumed silica content on the thermal and dielectric properties of BCE resins, and results showed that the addition of fumed silica could effectively improve the thermal and dielectric properties of BCE resin. Zhang et al 20 investigated the morphology and properties of cyanate/liquid polyurethane/silica composites, and results showed that the silica was uniformly distributed in the matrix, and the composites displayed higher fracture toughness and impact strength compared with other binary systems.…”