Effect of Calcium Carbonate Particle Size and Content on Polyamide 6 Processing and Properties

Three different types of calcium carbonates, including a nanosize one, were incorporated into polyamide 6, at different contents (5, 10 and 20 wt%) using a corotating twin-screw extruder connected to a Haake torque rheometer. Spherical-like nanosize CaCO3 particles and needle-like precipitated CaCO3 showed to consist of calcite crystals, whereas needle-like naturally occurring CaCO3 particles consisted of both calcite and aragonite. Specimens were injection molded and subjected to tensile, bending and impact testing. XRD, SEM and DSC analyses were also carried out. Both conventional and nanocalcium carbonate reduced torque, with the nano resulting in lower values. All investigated calcium carbonates increased PA6 tensile and flexural strength and elastic modulus.