Effect of supramolecular structure on the morphology of the surface of carbonized polytetrafluroethylene

Abstract

The morphology of the surface of polytetrafluoroethylene (PTFE), subjected to chemical etching in a sodium naphthalene solution in tetrahydrofuran, is studied by high-resolution scanning electron microscopy. It is shown that along with the molecular defluorination processes, etching of the polytetrafluoroethylene surface leads to surface fragmentation and crack formation. The emerging microstructure of the etched surface is associated with the bulk supramolecular structure and rheological properties of the polymer. The decreasing ductility of polytetrafluoroethylene after the pressing and sintering of polymerizate particles results in an increase in the number of cracks per unit area. The orientation of fibrils under uniaxial tension and the formation of spherulites, occurring upon radiation modification, is manifested in the preferred orientation of cracks. Increasing density and decreasing porosity of PTFE significantly lower the etching rate and the depth and length of cracks.