International audienceThe concentration dependence of specific heat, electrical and thermal conductivities of nanocomposites based on high-density polyethylene (HDPE) filled with silver nanoparticles have been investigated. The composites filled with high filler content show high electrical and thermal conductivities. The dielectric relaxation spectroscopy was used to investigate the electrical properties in the studied systems. The scaling law of electrical percolation was used for an exact estimation of the percolation threshold (Pc). A low electrical percolation threshold was found in the investigated composites. The rule of mixture was sufficient for the prediction of the specific heat dependence of HDPEAg nanocomposites as a function of the weight filler content. The basic models of the thermal conductivity have a tendency to underestimate the measured values for the low and high filler concentrations

Magnetic properties of a doped linear polyarylamine (PA2), whose chain includes alternating para-phenylene and meta-phenylene groups, and of two cyclic and linear model compounds (C2 and D2) were explored by pulsed-EPR nutation spectroscopy, SQUID magnetometry and DFT calculations. Stoichiometrically doped PA2 samples exhibit a pure S = 1 state (exchange coupling constant J = 18 K) with a high spin concentration (0.65) corresponding to 65% of mers bearing holes. Such properties were already observed for doped reticulated polyarylamines but are quite unusual for doped linear polyarylamines. In order to better understand the properties of PA2, model compounds C2 and D2 were also investigated: pure S = 1 spin states could also be obtained, but with higher J (respectively 57 K and 35 K) and, surprisingly, with high but still limited spin concentrations (respectively 0.77 and 0.65).