Abstract: Effect of DTBP on the behavior of XPS foaming with supercritical CO2 was studied. It was observed that when the DTBP content was higher than 0.5 ％, the weight average molecular weight of PS decreased sharply, accompanied by a decrease in melt viscosity. When the mold temperature was 112 ℃, the mold pressure was 4 MPa； DTBP content was lower than 0.3 ％, the apparent density of XPS foam decreased remarkably. A higher DTBP content could slow down such decrease. The introduction of DTBP caused modules, compressive and flexural strengths increased, but the flexural modulus decreased.

Key words: mechanical property, polystyrene, extrusion foaming, supercritical fluid, di-tert-butyl peroxide