| abstract |
A process for stabilizing aqueous dispersions of polytetrafluoroethylene (PTFE) or co- and terpolymers of PTFE by adding a macromolecular species directly to the aqueous dispersion. Surprisingly, it has been observed that after the macromolecular species has been added to the dispersion of PTFE or PTFE co- and terpolymers, the dispersions are very stable, do not coagulate easily, and remain stable even when subjected to cycles of freezing / melting. The amount of macromolecular species that can be added can vary from about 0.1% by weight to about 20.0% by weight, for example, and suitable macromolecular species include polyacrylic acid (PAA), polyvinyl alcohol (PVOH), polyethyleneimines (PEI) and polyethylene glycol (PEG), and others, the present method is particularly effective for stabilizing commercially available "non-stabilized" aqueous dispersions of PTFE or PTFE co-and terpolymers, which do not include a surfactant or are substantially free of surfactant. |