Developing toughened bismaleimide-clay nanocomposites: Comparing the use of platelet and rod-like nanoclays

Rod-like sepiolite organoclays are incorporated into a simple, first-generation commercial bismaleimide (BMI) to improve the inherent brittleness of the cured polymer; montmorillonite clay is used as a baseline comparison. Both solution and solid state blending methods are evaluated to determine which offer the best method of dispersion. Increased Pangel B40 (sepiolite) loading leads to finer particle sizes and a narrower size distribution indicating that the nanoclay assists the grinding and particle size refinement. The cured nanocomposites containing sepiolite nanoclays offer superior storage modulus to the montmorillonite. Introduction of Pangel B40 achieves around a 15–42% increase in plane-strain fracture toughness (depending on loading) and modest increases (+2%) in char yield when compared with the unmodified BMI.