Particle Size Limits for Sintering Polymer Colloids without Viscous Flow

Abstract

Effects of particle size on sintering of amorphous polymer colloids at temperatures at or above the glass temperature Tg were examined. Experiments on acrylic copolymers confirm the existence of a maximum particle size and minimum packing fraction for sintering to occur without any contribution from viscous flow. Within these limits sintering occurs by retarded elastic deformation at temperatures near Tg, and the kinetics for linear polymers are indistinguishable from those of cross-linked analogues. Sintering of larger particles and/or lower packing densities requires much higher temperatures or longer times as determined by the melt viscosity. The limiting sizes and packing densities are in good accord with estimates derived from the theory of adhesive contacts.