Effects of graded porous structures on the mechanical and electrical properties of Ketjenblack/silicone-rubber composites

●Ketjenblack/rubber composites with gradually changing pore sizes are produced.●Pore sizes and distributions of the composites are evaluated by X-ray CT.●Resistivities of the composites decrease greatly even in high compression rate.●Strain distributions of the composites under compression are analyzed by DIC.●Suitability of the composites as strain sensor materials is demonstrated. [Display omitted] In this study, Ketjenblack/silicone-rubber composites with gradually changing pore sizes are produced to develop strain sensor materials whose electrical resistivities change with an increase in strain. The pore sizes and distributions are evaluated by X-ray computed tomography and compared to uniform porous composites containing the same ingredients. Results showed that the resistivities of the graded porous composites decreased more significantly than those of the uniform porous composites at high compression rates of greater than 20%. Analytical results of strain distribution based on the digital image correlation method indicated that the resistivity changes at high compression rates were caused by a gradual increase in size of the area with low resistivity. The changes in resistivity demonstrated that graded porous composites are promising strain sensor materials that can be used under high compression rates.