A novel whitening test method of a sulfur-cured EPDM composite filled with carbon black in calcium cation solution

A simple and efficient whitening test method of a carbon black-filled sulfur-cured EPDM composite by formation of calcium stearate was established using Ca²⁺ solution and convenient analytical techniques. The sample was aged in 0.1 M CaCl₂ solution at 30–90 °C for 1 and 3 days. ATR-FTIR spectra of the aged sample surfaces displayed unique calcium stearate peaks. Level of the whitening of a rubber article can be determined by analysis of the cross section of the aged sample using an image analyzer and by analysis of calcium stearate on the aged sample surface using an ATR-FTIR.