Richard J. G. Dominguez

Impact Properties of Reinforced RIM Fascia

1. Improve dimensional stability particularly thermal dimensional stability 2. Lower the coefficient of linear thermal expansion (CLTE). 3. Increase stiffness to reduce droop in unsupported areas. Although milled glass does in fact improve the above performance properties, it is known to adversely affect impact performance. Many impact tests have been used to study the impact performance of polymeric materials. Recently, variable rate impact testing has emerged as a very sophisticated method for studying the impact performance of polymer composites. This method has been applied to the study of reinforced RIM urethanes (3). One of the more widely used instruments of this type is the Rheometrics High Rate Impact Tester. With our recently acquired Rheometrics instrument we decided to make a detailed study of the impact properties of a variety of reinforced RIM fascia.

Polyurea RIM: novel applications and technical advances

THE DEVELOPMENT OF polymeric material systems that can be processed via the Reaction Injection Molding or RIM process has been an active field of industrial research for more than a decade [1,2]. Polyurea RIM materials are the most recent development to result from this effort [3-5]. In this paper we will discuss some recent advances in polyurea RIM technology. In order to allow the reader to fully appreciate the contribution that polyurea RIM materials have made to our industry, we will first review the history of RIM material development. The focus of our review is to enable the reader to understand how polyurea RIM materials address the processing and property needs of the RIM industry.

The Effect of Annealing on the Thermal Properties of RIM Urethane Elastomers

Reaction Injection Molded (RIM) polyurethane elastomers are receiving a good deal of attention from the automobile industry. In recent papers by Liedtke1 at General Motors Manufacturing and Development, Mikulec2 at Ford PDAO and Lloyd3 at Texaco, it has become apparent that RIM polyurethane elastomers are a leading candidate for making automobile exterior body panels. One very important performance property in this end use is thermal dimensional stability. This is so for two reasons: first, paint bake cycles tend to involve relatively high temperatures, around 280–350°F and second, in use temperatures are often rather high for long periods of time. A part made from a RIM polyurethane elastomer should be able to withstand these conditions without an unacceptable degree of distortion.

RIM Urethanes: Heat Sag Characteristics

The &dquo;heat sag&dquo; test, ASTM D 3769-79, is used extensively to rank order the thermal dimensional stability of Reaction Injection Molded (RIM) fascia polyurethane elastomers. The test measures the magnitude that a sample droops during a specified high temperature oven cycle under gravity load. In general, it is difficult to compare quantitatively the results obtained from this test by different laboratories. Much of the problem centers on not knowing which variables affect the results and to what degree. This study addresses these questions in detail. The automobile industry has begun to look at RIM polyurethane materials for exterior body panel applications. The &dquo;high mod&dquo; materials useful in this new application are much stiffer than the relatively pliable fascia materials which are used commercially today. Also, the temperature performance requirements imposed