Gas-assisted reaction injection molding (grim): Application of the gas injection technology to the manufacturing of hollow polyurethane parts

The gas injection technology is gaining constantly in importance for thermoplastic polymers and could also offer a great potential of application to the manufacturing of polyurethane parts. Due to the significant differences concerning the material behavior between thermoplastics and reactive PU systems with their coupled chemical and physical processes this molding concept, designated as Gas-assisted Reaction Injection Molding (GRIM), has been investigated. Numerous experimental investigations concerning the most significant process parameters as well as a rheokinetic characterization have been performed. A selection of the results is presented within this paper.