Multiple response optimization of wood sawdust/natural rubber foam composites for stair tread covers

Examination of the optimal condition for wood sawdust (WS)/natural rubber (NR) foam composites is important for developing force-absorbing materials that can reduce the likelihood of accidents and injuries to the elderly. In this study, the Box–Behnken design and response surface methodology were used in experiments to determine the optimal condition for foam composites. The effects of the blowing agent, wood sawdust, and forming temperature on mechanical characteristics were also investigated. It was found that energy absorbed by the foam composites decreased with an increase in WS contents, but the hardness increased as well. The peak impact force of the foam composites reduced with the increasing addition of the blowing agent, though the coefficient of friction rose. Further, the fitted models were employed for optimization based on a desirability score that balanced multiple responses. An optimal condition for the WS/NR foam composites used to produce stair tread covers consisted of a blowing agent of 12 phr, wood sawdust of 44 phr, and forming temperature of 117 °C. Foam composites made with this condition had effective mechanical properties that closely agreed with the predicted values from the fitted models.