Narrow Results

The effect of sintering dispersed dispersion and nano-emulsion particles of high molecular weight polytetrafluoroethylene (PTFE) on a substrate as a function of "melt" time and temperature is described. Folded chain single crystals parallel to the substrate and as ribbons on-edge (with double striations), as well as bands, are produced for longer sintering times; particle merger and diffusion of individual molecules, crystallizing as folded chain, single (or few) molecule, single crystals when "trapped" on the substrate by cooling occur for shorter sintering times. It is suggested the observed structures develop with sintering time, in a mesomorphic melt. The structure of the nascent particles is also discussed.

The effect of sintering dispersed and bulk, low molecular weight (M_n = 50,000 Da), nano-emulsion polytetrafluoroethylene (PTFE) particles near their melting point is described. With the nascent particles consisting of ca. 75 nm diameter, hexagonal, single crystals, sintering at, e.g., 350°C, results, initially, in merger of neighboring particles, followed by individual molecular motion on the substrate and the formation of folded chain, lamellar single crystals and spherulites, and on-edge ribbons. It is suggested these structures develop, with time, in the mesomorphic "melt". Sintering of the bulk resin yields extended chain, band structures, as well as folded chain lamellae; end-surface to end-surface merger, possibly by end-to-end polymerization, occurs with increasing time.