The use of an electric field in the preparation of glass fibre/epoxy composites containing carbon nanotubes

This paper focuses on the use of electric field for the alignment of carbon nanotubes in glass fibre reinforced thermosetting composites and the associated infusion processing and property modifications. A satisfactory dispersion leads to high quality infusions with uniform distribution and infiltration of intrafibre microchannels by the nanofiller. Field application causes a reduction of resistivity during the process. The resistivity reduction follows an exponential decay with relaxation times in the 100-300 s range. This process is attributed to preferential aggregation in the field direction, whilst indications of individual nanotube alignment are found. The through thickness conductivity of the composite increases by an order of magnitude with the application of the field reaching a value of 1.4 × 10−3 S/m for 0.1 wt.% nanotubes. The in plane conductivity remains unaffected. The interlaminar toughness increases slightly but statistically significantly upon the addition of nanotubes. A high field leads to a further increase of strain energy release rate to 520 J/m2, which corresponds to a value 20% higher than the control. The effects observed on electrical properties are attributed mainly to preferential network formation in the field direction, whilst improvements in interlaminar toughness are linked to the nanotube alignment.