Hybrid Foamed Co-Injection Molding

Abstract

<p>This project examines the co-injection molding of a TPO material, using a solid skin, and a microcellular core material. For useful industry applications, the density, and the tensile and flexural mechanical properties were examined, and compared to a solid injection molded TPO plaque achieve using different processing parameters and materials. Correspondingly, the foam structure was examined to determine structural effects on the final mechanical properties. It was discovered that density can be reduced by as much as 32.0% ±0.8%, while still maintaining mechanical properties comparable to those of a similar part using a solid material for the core. Elliptical cellular shapes and cells distributed more widely in the gap direction corresponded with lower density parts, yet maintained mechanical properties similar to higher density foams with circular cells concentrated along the center of the gap direction.</p> <p>Fracture initiation was examined to determine if failure occurred within the foam structure of the parts, or the foam/core interface. Observations indicate that failure depended on the type of force applied to the part, as well as the material used to form the part itself.</p>