Low-temperature sintering behavior of Ag nanoparticles was investigated. The nano Ag particles used (ϳ20 nm) exhibited obvious sintering behavior at significantly lower temperatures (ϳ150°C) than the T m (960°C) of silver. Coalescence of the nano Ag particles was observed by sintering the particles at 150°C, 200°C, and 250°C. The thermal profile of the nanoparticles was examined by a differential scanning calorimeter (DSC) and a thermogravimetric analyzer (TGA). Shrinkage of the Ag-nanoparticle compacts during the sintering process was observed by thermomechanical analysis (TMA). Sintering of the nanoparticle pellet led to a significant increase in density and electrical conductivity. The size of the sintered particles and the crystallite size of the particles increased with increasing sintering temperature.

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Many mechanical and rheological properties of polymers are related to the amount and the distribution of its free volume. In this work, the evolution of free volume and its distribution in a linear model polymer resembling polyethylene under extensional strain are studied using a combination of molecular dynamics (MD) and Voronoi tessellation. When the molecular orientation due to stretch increases, the total number of voids in the sample decreases along with the number-average void size, while the number of larger unoccupied regions in the polymer increases, which become more elongated due to stretch. The hand-sphere probe shows that the overall free volume is decreasing during stretching; however, the reduction is not distributed evenly in the region. Free volume associated with atoms located away from the ends of molecular chains decreases while the free volume associated with atoms located at the molecular ends increases with stretch. Results from this computational work are in good agreement with several experimental observations reported in the literature.