Flammability Properties of Polymer Nanocomposites with Single-Walled Carbon Nanotubes: Effects of Nanotube Dispersion and Concentration
Takashi Kashiwagi, F Du, K Winey, K M. Groth, John R. Shields, S Bellayer, H J. Kim, Jack F. Douglas
The effects of the dispersion and concentration of single walled carbon nanotube (SWNT) on the flammability of polymer/SWNT nanocomposites were investigated. The polymer matrix was poly (methyl lmethacrylate) (PMMA) and the SWNT were dispersed using a phase separation ( coagulation ) method. Concentrations of up to 1 % by mass were considered. Dispersion of SWNTs in these nanocomposites was characterized by optical microscopy on a micrometer scale. Flammability properties were measured with a cone calorimeter in air and a gasification device in a nitrogen atmosphere. In the case where the nanotubes were relatively well-dispersed, a nanotube containing network structured layer without any major cracks or openings was formed during the burning tests and covered the entire sample surface of the nanocomposite. However, nanocomposites having a poor nanotube dispersion or a low concentration of the nanotubes (0.2 % by mass or less) formed numerous black discrete islands with vigorous bubbling occurring between these islands. Importantly, the peak heat release rate of the nanocomposite that formed the network layer is about a half of those which formed the discrete islands. It is proposed that the formation of the discrete islands is due to localized accumulation of the nanotubes as a result of fluid convection accompanying bubble formation and rise of the bubbles to the surface through the molten sample layer and of bursting of the bubbles at the surface. The network layer consisted of mainly the nanotubes with a small amount of thermally stable hydrocarbons and amorphous carbons. The layer acts as a heat shield to slow the thermal degradation of PMMA.
flammability, nanocomposite, PMMA, single walled carbon nanotube
, Du, F.
, Winey, K.
, Groth, K.
, Shields, J.
, Bellayer, S.
, Kim, H.
and Douglas, J.
Flammability Properties of Polymer Nanocomposites with Single-Walled Carbon Nanotubes: Effects of Nanotube Dispersion and Concentration, To Be Determined, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=861326
(Accessed February 27, 2024)