Analysis of the process influences on injection molded thermosets filled with hollow glass bubbles

Thermoset molding compounds have a wide range of beneficial properties such as easy handling, high temperature, chemical resistance, low shrinkage as well as low electrical conductivity. However, these properties come at the cost of a higher density than technical thermoplastic materials and thus the potential for lightweight applications is reduced. Due to the low viscosity of the resin within thermoset molding compounds a wide variety of filler materials can be used. The addition of low density hollow glass bubbles as a filler material in thermoset molding compounds offers the opportunity to decrease the density of the molding compound. At the same time the stiffness of the micro glass bubbles is expected to increase the stiffness of the material. In the present study, a thermoset molding compound was filled with different quantities of hollow glass bubbles and the effects of the filler content as well as the processing parameters were investigated regarding their effect on the weight and mechanical properties of the parts. Based on the results, significant weight reductions up to 5% were achieved. Furthermore, a significant impact of the process parameters on weight reductions was found. The results indicate that higher shearing reduces the weight. This can also contribute to damaging of the glass bubbles during the injection molding process. Similar results were found regarding the effect of process parameters on the mechanical properties.