Development of carbonized wood/silicon dioxide composite tailored for single-density shoe sole manufacturing

Abstract

Response Surface Methodology (RSM) and the Normal Boundary Intersection (NBI) method were utilized in this study for modeling and multi-objective optimization of carbonized wood/silicon dioxide composites. Operational variables such as particle size, carbonization temperature, filler content, curing temperature, curing pressure, and curing time were simultaneously adjusted to improve the tensile, hardness, density, and water absorption characteristics of the composite. RSM models were developed utilizing an experimental approach based on the Central Composite Design (CCD). The models showed outstanding correlation coefficient, with a threshold of 0.9959 and was therefore employed as the fitness function for the NBI algorithm's multi-objective optimization. A set of optimal compromise solutions was found at 25 µm particle size, 200 °C carbonization temperature, 51 phr filler content, 150 °C curing temperature, 3 Pa curing pressure and 10 min curing time; this formular results in 19.22 MPa tensile stress, 1.08 g/cm3 density, 97.15 hardness (shore A) and 7.18% water absorption. The optimum material formular was then deployed in single-density shoe sole manufacturing using a predesigned steel mould. Fourier-transform infrared spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) were used to characterize the new material.