Rheology and processability of multi-walled carbon nanotubes—ABSE polycarbosilazane composites

An inexpensive method has been found to produce ceramic SiCN-fibres via the precursor route consisting of five processing steps: synthesis of the polymer, preparation of the spinning mass, melt-spinning, curing via electron beam and subsequent pyrolysis at 1100 °C in a nitrogen atmosphere. A special solid and meltable fibre polymer, the so-called polycarbosilazane ABSE, has been developed in the last decade for this purpose. Due to its low molecular weight, an adequate catalytic and thermal aftertreatment was necessary to guarantee a stable melt-spinning process. This article discusses an alternative way to tailor the rheology of the spinning mass, i.e. the addition of multi-walled carbon nanotubes (MWCNTs) to the ABSE melt. Measuring the viscoelastic properties of the prepared compounds as well as their behaviour during the melt-spinning process demonstrates the strong interaction between the MWCNTs and the precursor melt. Even 1 wt.% of the MWCNTs shows a significant positive influence on the rheological behaviour and thus an improvement in the spinnability of the ABSE crude precursor. The influence of the addition of a dispersing agent is investigated as well. In using a dispersing agent, the level of homogeneous dispersion of the MWCNTs increases, whereas the interactions between the MWCNTs and the precursor melt decrease. Thus, the addition of MWCNTs represents a new way to modify the ABSE precursor for the melt-spinning process.