SAXS-XPCS investigation of the polymer-nanoparticles friction coefficient in magnetic nanocomposites of various viscosities submitted to an

We investigate Fe3O4 nanoparticles (NPs) embedded in polypropylene of various molecular weights with the aim to elucidate the impact of the host polymer linear viscoelastic properties on their temperature evolution (T(t)) when submitted to an oscillatory magnetic field (OMF). In a previous SAXS-XPCS experiment conducted at ESRF, we demonstrated that thermoplastic polyurethane filled with magnetic nanoparticles exposed to an OMF exhibited a two-step heating profile including:
1)Initial magnetic hysteresis losses caused by Weiss domains’ walls motion resulting in a T(t) exponential rise function.
2)Heat dissipation from NPs friction within the polymer matrix above its melting point resulting from the gigantic drop of viscosity.
By measuring the NPs structure (SAXS) and dynamics (XPCS) in presence of an OMF generating a temperature ramp, we aim to identify the variables that modify the friction coefficient and quantify their impact on the amplitude of the "2nd" heating mode.