Title: Weatherable Molded-in-Color Composites: Mechanisms and Relationships of Accelerated Test Methods and Geometry

Authors: Santosh K. Yadav and Paul A. Rettinger

DOI: 10.33599/nasampe/c.19.0810

Abstract: Which weathers better: a molded-in-color composite that is textured, or one that is not? Does surface geometry or test method affect weatherability that is achieved in a molded in-color composite? Most importantly, how do we measure our results? How do we understand our data as relates to change in appearance of an object out-of-doors, over time, as witnessed by a human observer? To begin to address these questions, this paper focuses on sheet molding compound and examines an array of variables that include, but not are limited to resin, filler, colorant, additive packages; compounding; mold conditions; and – last, but not least – the weathering protocol that is employed. Our study focuses on sheet molding compound, otherwise known as “SMC.” We have found that interactions between variables, or elements of a composition, are often difficult to predict. As such, the variables and components are known to cause unexpected dilemmas for the formulator. While this is true in general of exterior composites, this is especially true for SMC. Consequently, a multi-disciplinary approach is necessary be able to produce weathering results that are consistent with the demands of the end user, including the transportation industry. Multiple variables are evaluated, specific modes of degradation are identified, and the methods for controlling expected photodegradation are revealed.

References: 1. Rettinger, Paul A.; Mason, Lora; and Shah, Mayur. “UV Stable, Weather Resistant Sheet Molding Compound: An Alternative Approach to Building Strong, Durable Transportation Composites,” Automotive Composites Conference and Exposition, 2016. 2. Performance Based Standard for Accelerated Exposure of Automotive Exterior Materials Using a Controlled Irradiance Xenon-Arc Apparatus; SAE J2527. 3. Standard Practice for Xenon Arc Exposure Test with Enhanced Light and Water Exposure for Transportation Coatings; ASTM D7869. 4. Rettinger, Paul A.; Brannon, Selby M.; and Lewis, Jeffrey D. “A Short Guide to the Formulation of Exterior-Durable Composites,” SPI/CI International Conference, 1998. 5. Rettinger, Paul A.; Selby, M; Gleditsch, C. E., and Sykes, M. “A molded-in-color UV-Stable Sheet molding Compound: One Step Beyond. SPE 2001. 6. Sampers, J; Hutten, E., and Gijsman, P. “Accelerated weathering of unsaturated polyester resins. Aspects of appearance change” Polymer Testing 2015, Vol. 44 Page 208-223. 7. Rettinger, Paul A.; Brannon, Selby M. “The Color-Dependent Characteristics of Weatherable Thermoset Composites” 2004.

Conference: CAMX 2019

Publication Date: 2019/09/23

SKU: TP19-0810

Pages: 13

Price: $26.00