Influence of carbon nanotubes on thermal response and reaction to fire properties of carbon fibre-reinforced plastic material

The influence of the carbon nanotube content on thermal response and reaction to fire properties of carbon fibre-reinforced plastics (CFRP) is investigated in detail. A CFRP material filled with 1.0 and 2.0wt.% carbon nanotubes within the epoxy matrix shows increasing thermal conductivities perpendicular to the fibre fabrics direction. Therefore, laminate panels containing an increasing amount of carbon nanotubes exhibit lower temperature and internal stress gradients, and, for this reason, a less pronounced tendency to form delaminations during a one-sided thermal load. In a temperature range where rapid matrix degradation takes place, smaller damages are observed by ultrasonic analysis, and higher interlaminar shear strengths are retained. Backside temperatures rise with increasing amounts of carbon nanotubes, resulting in a more thermally degraded polymer matrix, as recorded by infrared spectroscopy at the backside. By adding carbon nanotubes into the matrix, ignition is retarded, the peak heat release rate is reduced and a more steadily combustion is achieved when the reaction to fire properties are investigated by cone calorimetry. Correlations between matrix degradation, recorded by infrared spectroscopy, and temperature, as well as residual strength, provide a reliable tool for non-destructive testing.