Mechanical and impact performance of three-phase polyamide 6 nanocomposites

• Secondary nanofillers enhance the polyamide-6 nanocomposite properties.
• Highly sensitive to the percentage and type of filler selection.
• Optimum filler content for polyamide-6 nanocomposite found.
• Nanoclay (OMMT) improved energy absorption and crash behaviour.
• Polyamide-6/glass fibre/3 wt.% SiO2, enhanced mechanical properties.

In this work, three-phase nanocomposites using multiscale reinforcements were studied to evaluate the influence of nanofillers on static and dynamic mechanical properties at varying temperature conditions. In particular, short-fibres reinforced polyamide 6 (30 wt.%) composites with various weight fractions of montmorillonite (OMMT) and nanosilica (SiO2), manufactured and investigated. Quasi-static tensile properties were investigated at room temperature and also at 65 °C just above the polyamide 6 (PA6) glass transition temperature. The low velocity impact tests were conducted on the manufactured cone-shaped structures to evaluate the crash behaviour and energy absorption capability. The study results shows that the increase of the weight percentage level of OMMT in PA6/glass fibre (30 wt.%) composite made the nanocomposites more brittle and simultaneously deteriorated the tensile properties. SiO2 nanofiller at 1 wt.% was found to be the optimum ratio for improving tensile properties in silica-based nanocomposites studied. It was further noted that for both types of nanofillers, the crashing behaviour and energy absorption in dynamic properties were improved with increase in nanofillers weight percentage in the composites. The study also shows that the brittleness behaviour of the nanocomposites investigated is associated to the fibre/matrix interaction which is dependent on the nanofiller type and has significant effect on crash modes observed.