A study of the thermo-mechanical behavior of Boehmite-polyamide-6 nanocomposites

Some of the important thermo-mechanical characteristics of Boehmite-polyamide-6 nanocomposites are presented. Two different types of Boehmite (γ-AlOOH) are investigated, which are unmodified and surface-modified using a titanate-coupling agent. Since use-temperature range is one of the most important parameters for engineering polymers, heat distortion temperature (HDT) and glass transition temperature (Tg) of the nanocomposites are analyzed in detail. According to the dynamic mechanical analysis (DMA), both storage and loss modulus show a gradual increase with (Ti-)Boehmite concentration. Compared to the HDT of the unfilled polymer (67 °C), there is a tremendous increase in HDTs of the nanocomposites up to 143 and 155 °C at 9% Boehmite and 15% Ti-Boehmite contents, respectively. PA6-Boehmite samples show a random variation in Tg values whereas the PA6-Ti-Boehmite samples have a certain trend: Tg values gradually decrease in the beginning, and then increase with filler concentration. It is shown that both series of nanocomposites have similar thermo-oxidative stabilities. Therefore, both the trend in Tgs and the lower HDT values at low Ti-Boehmite contents are attributed to the plasticizing effect of the titanate-coupling agent. Complex Halpin–Tsai model has been used to assess the temperature-dependent mechanical properties of the nanocomposites.