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Stress Cracking of Polycarbonate Exposed to Sunscreen
ISSN: 1946-3979, e-ISSN: 1946-3987
Published April 12, 2011 by SAE International in United States
Citation: Krishna, A. and Berg, E., "Stress Cracking of Polycarbonate Exposed to Sunscreen," SAE Int. J. Mater. Manuf. 4(1):152-157, 2011, https://doi.org/10.4271/2011-01-0037.
Pushbuttons, knobs and plastic faceplates in automotive interiors are constantly exposed to chemicals such as sunscreen. In some instances, structural degradation of the plastic may occur with specific chemical agents and degradation can also be accelerated by high temperatures. A study of the propensity of commercial polycarbonate (PC) to craze and ultimately crack when exposed to sunscreen is outlined in this paper. Three-point bend testing per ASTM D3929 results in permissible bending strain limits for prolonged exposure to sunscreen at elevated temperatures. The paper outlines implementation details of these strain limits applied to a button surface, including finite element analyses identifying strain at the observed failure locations. Design considerations for related parts and products are also outlined.