Investigation of the Thermal Resistance of Phenolic Resin/Glass Fiber/Nanosilica Nanocomposites

Hypothesis: Glass-reinforced composites are used in the production of passively cooled combustion chambers. To improve the performance of these composites as well as to decrease their costs, the use of micron sized silicon dioxide particles has been widely used. In this work, the possibility of producing glass phenolic composites with nanosized silica as an alternative to micron-scaled silicon dioxide was investigated. In order to disperse nanosilica in composites uniformly, a combination of sonication and high stirring was used. In all cases, the blends were prepared according to following procedure: the resin was weighed and diluted in methyl alcohol, and then the selected amount of nanosilica was added. The resultant mixture was sonicated and stirred for 1 h simultaneously. For preparation of glass fiber nanocopmpsites, a theoretical amount of chopped strands was weighed first and then the fibers were mixed with resin or the nanocomposites. Each produced paste was placed in a cylindrical shaped mold and then the mass was compression molded at a pressure of about 10 bar and cured at 180°C. The thermal resistance properties of the produced materials were studied using an oxy-acetylene torch. In depth temperature profiles taken through the thickness of the samples, ablation and loss of mass data of the post-test surfaces were used to evaluate the effects of nanosilica. Furthermore, to investigate the material post-test microstructure, a detailed morphological characterization was carried out using scanning electron microscopy. Findings: In comparison to neat glass/phenolic composite, the introduction of just 2, 4 and 6 wt% nanosilica particles embedded in the matrix improved the mass loss of nanocomposites about 12, 19 and 31%, respectively