CONTROL OF CARBON FIBER-POLYPYRROLE INTERPHASES BY AQUEOUS ELECTROCHEMICAL PROCESS

The morphology, surface free energy and chemical composition of carbon fibers containing polypyrrole interphases has been determined. The mo rphology of the polypyrrole coated fibers was measured by scanning ele ctron microscopy (SEM). The surface microstructure of the interphases varied from smooth to rough and grainy. The electrolyte used in the fo rmation of polypyrrole interphases has a remarkable influence on the m orphology of the resulting coatings. The interphases formed by using t oluene sulfonate were either smooth, microspheroidal, leafoidal or rou gh. The surface morphology of the polypyrrole interphases formed by us ing duodecyl sulfonate and sulfuric acid are predominantly smooth and rough, respectively. The wettability of the polypyrrole modified carbo n fibers was estimated from the surface free energy of the fibers. Sig nificant improvement of the surface free energy of the electrochemical ly modified fibers (60 < gamma less than or equal to 75 dynes cm(-1)) over the commercially surface oxidized fibers (gamma = 51 dynes cm(-1) ), of about 40%, was obtained. Examination of the electrochemically fo rmed polypyrrole interphases, by infrared spectrophotometry (IR) showe d that the electrolytes were incorporated into the interphases. (C) 19 98 Published by Elsevier Science Limited. All rights reserved.