An experimental design approach in formulating a ceramifiable EVA/PDMS composite coating for electric cable insulation

The study used d-optimal mixture design of experiments to formulate a ceramifiable EVA/PDMS composite with optimized ceramified flexural strength properties after being exposed to elevated temperatures. The ideal amounts of inorganic fillers and their interaction within the polymer composite were studied. It was found that good polymer and ceramic properties were achieved when using 59% EVA/PDMS polymer blend with inorganic fillers of 11% calcium carbonate, 10% aluminium hydroxide, 11% muscovite mica, and 9% calcined kaolinite, respectively. TGA, SEM, and PXRD were employed to study the behavioral changes of the EVA/PDMS composite during and postceramification process. Although all inorganic fillers used were important, muscovite mica played a special role not only in the ceramification process, but also in keeping the ceramic product physically stable. Microstructural analysis of the cross-sectional area of the ceramic product showed that it was multilayered with an inhomogeneous distribution of the chemical composition across its layers. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers