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An Alternative Approach for Defining and Predicting Outdoor Performance for Sheet Molding Compound


Title: An Alternative Approach for Defining and Predicting Outdoor Performance for Sheet Molding Compound

Authors: O. Christopher Groth, Brian D. LaBorn

DOI: 10.33599/nasampe/c.22.0153

Abstract: Sheet molding compound is used in a wide range of applications which may require uncoated surfaces to perform outdoors over the lifespan of the molded component. Typical methods for testing outdoor durability are accelerated weathering chambers such as Xenon Arc or direct outdoor exposure in harsher environments such as in South Florida. The combination of color change via spectrophotometer readings and gloss retention over time are typically used to define the substrate’s resistance to moisture, UV radiation and temperature. However, the visual appearance of the part may differ from what the gloss retention and color change values may suggest. It was our goal to compare SMC formulations for weathering performance and at the same time optimize the formulations. Smooth molded panels were molded from a series of SMC formulations and tested with Xenon Arc. The series of SMC formulations that were evaluated include a 50 percent fiberglass structural black sheet molding compound designed to meet the criteria for structural transportation applications and 28 percent fiberglass low profiled SMC designed for non-painted outdoor transportation applications. In this paper we will define the weathering performance of the different substrates using a combination of visual observation, digital microscope photography, spectrophotometer readings and gloss readings. Combining these test results, we will summarize the performance of the different formulations.

References: 1. S. Yadav and P. Rettinger, Weatherable Molded-In-Color Composites: Mechanisms and Relationships of Accelerated Test Methods and Geometry, 2019-CAMX-The Composites and Advanced Materials Expo 2. Wicks, Z.W. Jr. et al, Organic Coatings: Science and Technology. 3rd ed. Hoboken NJ: John Wiley and Sons, 2007

Conference: CAMX 2022

Publication Date: 2022/10/17

SKU: TP22-0000000153

Pages: 14

Price: $28.00

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