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Keaction injection molding (HIM) elastomers are being seriously considered by major automotive companies as a substitute for metal in exterior body panels. One major consideration in this application is dimensional stability at a 325°F paint bake cycle. Kcported here are formulations which via novel processing result in finished parts with excellent dimensional stability at 325°F. In addition, other properties such as impact resistance and flex modulus ratio improve parallel with high temperature performance. Mechanical properties as a function of processing and molding parameters are presented. Other studies are presented and a tentative explanation of the superior performance of' these RIM elastomers is made.

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Polyurea RIM, because of its production speed, internal release characteristics, high temperature dimensional stability, and increased resistance to water absorption is finally coming to the forefront as a better route to producing automotive body panels and fascia. One of the barriers that held back the rapid replacement of polyurethane-urea RIM by this new technology has been the increased reaction rate typically exhibited by polyurea RIM. The throughputs of existing RIM equipment were not high enough to produce some of the larger fascia and body panel parts.To address this need of some molders to process polyurea RIM in lower throughput RIM machines, we have investigated various modifications of our polyetheramines. Among the modifications investigated were the recently introduced ketimine technology, N-alkyl substituted polyetheramines and polyether amines having aromatic amine termination. The processing characteristics and physical properties of some of these slower polyether amines in polyurea RIM formulations will be discussed.

Considerable work has been published on the subject of filling reaction injection molded (RIM) polyurethane elastomers with discontinuous particulate fillers such as milled glass fibers, flake glass and wollastonite. RIM polyurethane elastomers are filled for three reasons: 1) to increase stiffness, 2) to decrease the linear coefficient of thermal expansion, and 3) to improve thermal dimensional stability. Discontinuous particulate fillers either do not appreciably change strength properties, e.g., tensile strength or they cause dramatic reduction in strength properties, e.g., impact resistance. To overcome these deficiencies, new fillers are necessary, One such material is continuous glass strand mat. In order to make continuous glass strand-polyurethane composites by the RIM process, a particular balance of ingredients to produce the RIM polyurethane must be used. We will discuss the properties of these composites and suggest possible applications and future directions in which this research might proceed.