Steam-Chest Molding of Expanded Polypropylene Foams. 2. Mechanism of Interbead Bonding

다국어 초록 (Multilingual Abstract)

<P>Expanded polypropylene (EPP) bead foams were processed using steam-chest molding. Interbead bonds formed during processing and was characterized by observing both the product surface and the fracture surfaces using scanning electron microscopy (SEM) and by measuring the tensile properties of specimens. It was found that both the degree of interbead bonding and the tensile strength had a direct relationship to the steam pressure/temperature and that high steam temperature enhanced the crystallization behavior of EPP beads during the cooling process. A formation mechanism of interbead bonding during processing was proposed based on the crystal melting behaviors, as discussed in the first article of this series (<name name-style='western'>Zhai</name> et al. Ind. Eng. Chem. Res.<x xml:space='preserve'> </x>2010<x xml:space='preserve'>, </x>49<x xml:space='preserve'>, </x>9822). Possible parameters influencing the formation of interbead bonding, namely, steam temperature/pressure and bead foam expansion ratio, were investigated in this study. The effect of postannealing of the EPP products on the shrinkage and crystallinity of the molded EPP products was also addressed.</P>