Modeling Approach for Reactive Injection Molding of Polydisperse Suspensions with Recycled Thermoset Composites

Area of Science:

• Materials Science
• Chemical Engineering
• Computational Fluid Dynamics

Background:

• Reactive injection molding (RIM) generates production waste.
• Recycling thermoset composite (RTC) waste with virgin thermoset composite (VTC) enhances sustainability.
• Existing mold-filling models do not account for viscosity changes with RTC reinforcement.

Purpose of the Study:

• Develop and validate a mold-filling simulation approach for polydisperse suspensions of RTC and VTC.
• Assess the impact of RTC reinforcement on processability and final part production.
• Improve the accuracy of mold-filling simulations for recycled composite materials.

Main Methods:

• An effective viscosity model was developed by extending the Cross-Castro-Macosko (CCM) model using the stress-strain amplification approach.
• The model was implemented in the OpenFOAM computational fluid dynamics code using an extended multiphase solver.
• Experimental trials with varying VTC/RTC compositions and injection speeds were conducted using a sensor-equipped mold.

Main Results:

• Reinforcing VTC with RTC was found to increase material viscosity.
• RTC-reinforced compounds necessitate higher injection pressures for successful mold filling compared to VTC alone.
• Simulations showed qualitative agreement with experimental pressure profiles across different RTC proportions and injection speeds.

Conclusions:

• The developed viscosity model effectively reproduces the mold-filling behavior of VTC/RTC mixtures.
• The simulation approach aids in predicting processability and the effects of recycled content in RIM parts.
• This work supports sustainable practices in composite manufacturing through effective waste recycling and simulation.