Dynamic viscosity of strontium ferrite–nylon composite below the melting temperature

Hard-magnetic 3D-printer filaments made of 40 wt. % SrO(Fe2O3)6/PA12 composites using a twin-screw extruder are being studied to be used for Magnetic Field Assisted Additive Manufacturing (MFAAM). The time dependence the magnetic properties above softening temperature PA12 matrix but below melting point was biaxial Vibrating Sample Magnetometer (VSM). Specifically, rotation particles in softened polymer after application field extracted from dependent VSM signals. Above 132 °C, strontium ferrite can rotate nylon matrix. measured constant decreases with and magnitude field. Model calculations indicate that, at fields 500 Oe, effect demagnetizing on angle between moment particle’s easy axis is negligible, allowing one determine dynamic “melt” viscosity transients. 2 × 105 Pa s °C 3.1 104 175 sharp kink observed near 140 that correlates relaxation α′c phase by others. A yield shear stress small low temperatures resulting non-perfect alignment particles. implications measurement results MFAAM discussed.