Thermal analysis of postcured aramid fiber/epoxy composites

Abstract

In this study, aramid fiber-reinforced polymer (AFRP) composites were prepared and then postcured under specific heating/cooling rates. By dynamic mechanical analysis, the viscoelastic properties of the AFRP composites at elevated temperatures and under various frequencies were determined. Thermomechanical analysis (TMA), in the modes of creep-recovery and stress–relaxation tests, was also performed. Furthermore, differential scanning calorimetry was also used, and the decomposition of the AFRP composites, aramid fibers, and pure postcured epoxy, in two different atmospheres, namely, air atmosphere and nitrogen (N2) atmosphere, was explored by the thermogravimetric analysis (TGA). From this point of view, the aramid fibers showed remarkably thermal resistance, in N2 atmosphere, and the volume fraction of fibers (Φf) was calculated to be Φf = 51%. In the TGA experiments, the postcured AFRP composites showed very good thermal resistance, both in air and N2 atmosphere, and this characteristic in conjunction with their relatively high T g, which is in the range of 85–95°C, depending on the frequency and the determination method, classifies these composites as potential materials in applications where the resistance in high temperatures is a required characteristic.

Investigations of thermo-mechanical properties of cryogenic and dual alkali-anhydrous treated hemp fibre and its composites

“…The fourth stage process (480°C2590°C) attributes to the decomposition of the a-cellulose and lignin with residuals of epoxides. 40 The significant increase in the peak inflexion point indicates the increase in the thermal stability of modified composite over untreated composite. 41 Differential thermal analysis (DTA).…”