The logarithm of the surface resistivity, log(SR), for a poly(ether sulphone)/carbon-fibre composite ranged between 6.23 and 10.66, depending on the conditions of moulding. The statistically significant variables were: the injection pressure, P~; the temperature of the mould, Tmould; and the temperature of the barrel, Tbarrel. The fibre lengths and distributions in the samples moulded under the extreme conditions for Tmou~d and P~ were not significantly different from each other--at 126pm and median lengths at 100-110 /~m. However, the lengths of the fibres at the surface of these samples, shorter than those in the centre, were slightly longer for the more conductive sample, which was moulded at maximum settings of both P~ and Tmou~d: the average fibre length was 114 + 77 pm and median 90-100/~m for the more conductive sample, compared with 109___ 82/~m and median 80--90#m for the sample moulded at minimum settings of P~ and Tmou~o. The trend in relative concentration of the fibres at the surface for these samples was consistent with that in the log(SR); the sample with lower SR had a slightly higher concentration of fibres from the surface through a depth of approximately 500#m. We propose a physical model whereby the content of fibres at the surface and their length influence the surface resistivity. Although the orientation of the fibres has the potential to influence the surface resistivity of the composites, there was no significant difference in orientation for samples examined in this study.
Посилання на статтю:
The effects of conditions of moulding on the surface resistivity in the range of 10 8 to 10 TM ohms/square of a carbon-fibre/poly(ether sulphone) short-fibre composite / Carol L. Schutte* and R. Owen Hutchins // Polymer. – 1993. – Vol 34. – P. 476-480.