Investigation of the effect of nanoparticle addition on the curing behavior of epoxy based composite materials

The study was carried out to evaluate the effects of epoxy-nanoparticle combination on the curing kinetics and mechanical properties of composite materials. While isothermal differential scanning calorimetry (DSC) was used to detect and evaluate curing kinetic behaviors, tensile, hardness and thermal conductivity experiments were carried out to determine mechanical properties. In addition, FTIR tests were performed to examine the bond structure of the samples in detail after curing. Studies have shown that TiO2 (%0.1-%0.5-%1.0), Al2O3 (%0.75-%1.25-%2.0) and graphene nanoplatelet (GNP) (0.25%-0.75%) were added to Hexion brand commercial Epikotem MGS L285 epoxy at different weight ratios. It was made by adding %1.0. The results of DSC analyzes performed at temperatures of 90-100-120 °C were modeled and graphed in the MATLAB program (using the curve fitting tool). The Kamal-Sourour kinetic model, which is the model that best describes the curing of epoxy-nanoparticle systems, was used to create mathematical models. The obtained kinetic parameters and the cure reactions of each system were analyzed according to Arhenius laws. According to the analysis results, the minimum activation energies were found to be 21.88 kj/mol in Al2O3, 11.12 kj/mol in TiO2 and 9 kj/mol in GNP; It was observed that the curves best suited to the Kamal model were formed at 100 °C for all particles. Since the lower activation energy of a chemical reaction means that this reaction will occur in a shorter time, it is thought that GNP will be the most meaningful model in reaching a 100% cured structure. At the optimum temperature value (100 °C) determined in the second step studies, DSC studies, tensile, hardness and thermal conductivity analyzes were carried out again, accepting the %0.75-1.0-1.25 contribution rates at which each nanoparticle system reached its highest curing speed as the common value. While the highest tensile strength was achieved in the samples with %1.25 Al2O3 added, the highest elongation at break was reached in the sample with %1.0 TiO2 added. On the other hand, the highest hardness was detected in the sample with %1.25 Al2O3 added. Compared to pure epoxy, an increase of %140.32, %175 and %7 in tensile strength, elongation at break and hardness, respectively, was detected. The highest thermal conductivity values were reached at %1.25 for all particles. Thermal conductivity; Compared to the reference sample, it increased by %123.5, %69 and %47, respectively, in GNP, TiO2 and Al2O3 added samples.