An Improved Method for the Dispersion Assessment of Flame Retardant Filler/Polymer Systems Based on the Multifractal Analysis of SEM Images

The dispersion quality of filler particles in highly loaded, flame retardant filled (FRF) polymer composites has been quantified using a complementary multifractal image analysis method. The use of an alternative imaging signal, backscattered electrons, greatly reduced the time required for image capture, relative to energy dispersive X‐ray signals discussed previously. Characteristic Dq multifractal spectra were calculated from BSE image data and multifractal curve width was once again observed to be a good indicator of dispersion quality. Numerically derived data was in strong agreement with a visual interpretation of images exhibiting variations in dispersion quality. This new method was used to study a series of FRF/EVA composite compounds based on aluminium hydroxide and magnesium hydroxide, both uncoated and coated with isostearic acid. Results from a screening experimental design were used to investigate the effect of material formulation on dispersion quality. Variations in dispersion quality observed in formulations based on isostearic acid treated filler could be related to the differing isostearic acid adsorption characteristics of the two metal hydroxides. Observed versus predicted scatter plot for the linear model describing the dependence of mean Dq curve width on material formulation.