Document Abstract
ANTEC Papers: 2001
0909: Importance of Timely Polymer Sintering versus Blowing Agent Decomposition in Rotational Foam Molding of Polypropylene
Remon Pop-Iliev, Ghaus M. Rizvi, and Chul B. Park* Microcellular Plastics Manufacturing Laboratory Department of Mechanical & Industrial Engineering University of Toronto Toronto, Ontario, Canada M5S 3G8 *park@mie.utoronto.ca
Producing polypropylene (PP) foams with satisfactory cell morphologies in rotational foam molding is feasible. However, the narrow interval between the melting temperature of PP and the onset decomposition temperature of the suitable chemical blowing agent (CBA), together with the low melt strength of PP at elevated temperatures, often represent the greatest obstacles in the foaming of PP. Experimental results revealed that the morphology of the foams obtained by processing PP pellets that have been pre-compounded with a CBA could be governed by either pellet sintering or cell coalescence. The viscosity of the basic PP resin and the processing temperature determine which of these two key factors will assume a predominating influence towards the foaming process. Desirable PP foam structures in compounding based rotational foam molding could be obtained only if pellet sintering takes place prior to the decomposition of the CBA and if the processing temperature during the foaming process is kept lower than the temperature of cell coalescence.