Effect of boron carbide nanoparticles on the thermal stability of carbon/phenolic composites

Abstract

In this work, the use of nano‐boron carbide as a nanomodifier of phenolic matrix was envisioned. Particularly, nano‐boron carbide/phenolic‐based nanocomposites were produced and investigated. The obtained nanostructured matrices were also used to produce carbon fiber‐based bulk molding compounds (BMC). The thermal stability of nanocomposites and BMCs was investigated by thermogravimetric analysis both in nitrogen and in air atmospheres. The good dispersion and distribution of the nanosized particles in the matrix was confirmed by transmission electron microscopy while the post‐burning appearance of the BMCs was investigated by visual inspection and scanning electron microscopy. The experimental data highlighted the remarkable effects of nano‐boron carbide on the thermal stability and oxidation resistance of the carbon fiber‐based BMCs. Moreover, the boron oxide produced by the conversion of boron carbide allowed a substantial improvement of the dimensional stability of the BMC which also exhibited considerable residual structural integrity after burning. POLYM. COMPOS., 38:1819–1827, 2017. © 2015 Society of Plastics Engineers

Effect of liquid resol on the mechanical and thermal properties of EPDM/Kynol elastomeric heat shielding materials

“…In nitrogen, the thermal degradation occurred in two steps; the first one (200–450°C) was related to the evaporation of paraffin oil and to the degradation of the phenolic matrix; increasing the resol content it was possible to evidence the typical degradation pattern of a resol in nitrogen . In a non‐oxidative atmosphere, above 500°C, all the tested materials exhibited the same thermal behavior and displayed the same residue.…”

“…Similarly to the TGA results in air, an increase in the resol content did not produce a corresponding increase in the char yield. If we calculate the char residue of the different formulations as the addition of the char yield of the constituents , the P20K, and the P40K should have produced an increase in the char yield ranging around ∼6% and ∼10%, respectively.…”

“…In order to improve the thermal resistance of elastomeric liners, the possibility to add to the rubbery matrix a high char yield resin such as phenolic was studied. Because of its chemical nature, NBR is a very suitable matrix to be modified with phenolic: the introduction of a phenolic phase could increase the erosion resistance and char yield .…”

Nanostructured phenolic matrices: Effect of different nanofillers on the thermal degradation properties and reaction to fire of a resol

“…The 5%‐B4C formulation exhibited the higher thermal stability since the DTG pattern was the lowest among the tested materials. This evidence can be related to the formation of boron oxide that is associated to a reduction of the produced gaseous species by virtue of chemical reactions between boron carbide and gaseous degradation products . In this way, the gaseous phase is solidified into the charred layer reducing the loss of mass and increasing the thermal stability.…”

“…25 Moreover, the surface of these nanostructured matrices is characterized by an increased emissivity that reduces the heat flux transferred into the material and, consequently, the mass loss rate. 26,27 The use of boron carbides as microparticles [28][29][30][31] and, in more recent years, as nanoparticles 32,33 has evidenced a remarkable potential to increase the thermal response of polymeric matrices. The presence of this kind of filler allows to obtain materials with an enhanced thermal stability, especially in oxidizing environments, because of the chemical modification that occurs at high temperatures in the presence of oxygen:…”