Abstract: The bubble breakup in polymer foaming process was studied by theoretical calculation and numerical simulation in this paper. For a given bubble in simple shear flow, the breakup time was calculated by a theoretical derivation method and was simulatedby a volumeoffluid method. The breakup times derived from the two ways were compared.The factors which influenced the bubble breakup time were analyzed, and it was found that the bubble breakup time was proportional to interfacial energy, and inversely proportional tointerfacial viscosity, bubble diameter, and the square of shearing rate.

Key words: polymer, foaming, breakup time, bubble radius, shear rates, interfacial energy, interfacial tension