Polypropylene (PP) bead foams were prepared by autoclave foaming using n-pentane and CO2 as the blowing agents. PP foams blown with n-pentane had foaming temperatures of 92-96 degrees C, expansion ratios of 10-50 times, and a signal T-m at 150.1 degrees C, while PP foams blown with CO2 had foaming temperatures of 151-153 degrees C, expansion ratios of 8-20 times, and dual melting peaks at 164.0 and 140.9 degrees C. Polyethylene (PE) addition was used to improve the foaming behavior of PP and to induce the formation of dual and multiple T-m in PP/PE foams. A differential scanning calorimetry procedure was carried out to simulate the steam-chest molding of bead foams. Interbead bonding was found to be determined by the heat of fusion of T-mc (crystal melting of the newly formed crystals during fast cooling), Delta H-mc. Recrystallization of the PE component contributed to the increase of Delta H-mc which potentially improved interbead bonding of the molded PP/PE bead foams.