Patrick Piccione

Shape and Temperature Memory of Nanocomposites with Broadened Glass Transition

Shape-memory polymers can revert to their original shape when they are reheated. The stress generated by shape recovery is a growing function of the energy absorbed during deformation at a high temperature; thus, high energy to failure is a necessary condition for strong shape-memory materials. We report on the properties of composite nanotube fibers that exhibit this particular feature. We observed that these composites can generate a stress upon shape recovery up to two orders of magnitude greater than that generated by conventional polymers. In addition, the nanoparticles induce a broadening of the glass transition and a temperature memory with a peak of recovery stress at the temperature of their initial deformation.

Determination of relevant “average” properties for tubular filler materials used in composites

Abstract To obtain the best estimate of the average diameter and number of walls of tubular objects such as carbon nanotubes, which are used as filler materials in composites, both inner and outer diameters must be taken into consideration. The appropriate weighting factor is calculated from the cross-sectional circular shell area. In the case of cylindrical objects, the formulae simplify considerably and the average diameter and wall thickness are the third moment of their distribution function. Two examples illustrate the numerical effects of these calculation procedures.

Rheological and Electrical Properties of PVDF Composites Based on Carbon Black and Carbon Nanotubes Synergy

Composites material based on PVDF, carbon nanotube (CNT) and carbon black (CB) are investigated in term of rheology and electrical properties. Due to their high aspect ratio, CNT leads to lower electrical percolation threshold along with high increases of viscosity. When using CNT and CB in ternary blends a synergetic effect is observed for electrical resistivity and viscosity.