MORPHOLOGICAL-CHARACTERISTICS OF CARBON POLYTETRAFLUOROETHYLENE FILMSDEPOSITED ON POROUS CARBON SUPPORT/

The effect of polytetrafluoroethylene (PTFE) content on morphological characteristics of carbon/PTFE films deposited on porous carbon suppor t was investigated by mercury-porosimetry, scanning electron microscop y (SEM) and a.c. impedance spectroscopy. The microstructure of the fil m was affected by the content of fluoropolymer. The layer has two dist inctive pore distributions with a boundary of about 0.35 mu m. The pol ymer coated the pores with size higher than 1 mu m (carbon interagglom erate pores), while the pores with size lower than 1 mu m were not inf luenced by the presence of PTFE. Above 40 wt% PTFE, a further supply o f polymer did not fill the pores, but increased the thickness of the s ample. The presence of cracks, increasing in number and size with PTFE content, was also revealed. (C) 1998 Chapman & Hall.