Surface properties of carbon fibres modified by electrodeposition of polyamic acid

The objective of this work is to study the surface property changes of carbon fibres resulting from the electrodeposition of polyamic acid. Unsized but surface oxidized carbon fibres were successfully coated with polyamic acid by non-aqueous electrodeposition. The surface property changes due to the electrodeposition were studied by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTi.r.), dynamic contact angle analysis (DCA) and thermogravimetric analysis (t.g.a.). The SEM analysis showed smooth, continuous and thick polyamic acid coatings. The electrodeposition of polyamic acid on graphite fibres did not result in a self-limiting film growth. FTi.r. spectroscopy confirmed that the electrodeposited coatings possessed the same chemical structure and functionality as the bulk polymer, indicating that electrodeposition did not result in alteration of the polymer structure. The surface energy of the coated T650/35 and T-300 fibres was found to be about 15% and 20% respectively, lower than that of the uncoated fibres. T.g.a study showed that the cured polyimide has excellent thermal stability up to 540 degrees C. Copyright (C) 1996 Elsevier Science Ltd.