Factors in blowing better foams

Rotomolders have used ADCA in powder form in their formulations to create foamed products. However, micropellet masterbatches are reportedly becoming more popular and offer improved foam quality. As in other processes, process control is important in rotomolding foams, since premature decomposition of the blowing agent can result in gas escaping from between the particles of unconsolidated resin during molding [13-2, 13-8]. 

Foaming introduces unique factors to monitor, since it is a process in which part quality is determined heavily by radical internal changes in the part. Various factors and additives can influence foam cell size, consistency, or quality. Other economic factors determine whether foaming may even be appropriate for an application. 

Particle size of blowing agent The particle size of an ADCA-based agent, for example, affects the size and structure of the foam cells produced. It also affects the temperature at which the blowing agent decomposes, with smaller particle sizes ( 2 j,m ) decomposing at lower temperatures [1-1]. 

The modification of PO resins with additives is not straightforward the PO matrix itself is often resistant to interacting with additives or the environment in the ways desired by the formulator or end user. After all, POs are relatively inert and nonpolar and tend to repel many additives, and other polymers. They also tend to resist degradation in places—such as landfills—where end users would prefer that they decompose. 

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