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Design and Interpretation of Laboratory Weathering Tests using Acceleration Parameters of Some Aromatic Engineering Thermoplastics

Published

Author(s)

Li Piin Sung, James E. Pickett, Olga Kuvshinnikova, Brett Ermi

Abstract

The NIST (National Institutes of Standards and Technology) SPHERE (Simulated Photodegradation via High Energy Radiant Exposure) was used to obtain acceleration parameters, such as activation energies, for bisphenol A (BPA) polycarbonate (PC), poly(butylene terephthalate) (PBT), a PC/PBT blend, and poly(styrene-co-acrylonitrile) (SAN) containing 3 % (mass fraction) rutile Titanium oxide (TiO2)white pigment. The responses were color shift and 60 deg gloss loss. The materials exhibited excellent reciprocity over the irradiance range of the SPHERE for both properties. Activation energies for color change were (16 to 21) kJ/mol and (9 to 16) kJ/mol for gloss loss. The effects for relative humidity (RH) were observed only for PBT and SAN and only for RH  10 %. Ultraviolet (UV) wavelength effects varied between the polymers. Exposures under modified ISO 4892-2 xenon arc conditions using filters with an excellent match to solar UV and relatively high irradiance were compared to exposure in Miami, Florida, taking into account temperature effects. The expected correlation accurately predicted color shift and gloss loss of the white samples. However, gloss loss of samples containing carbon black was not properly predicted, indicating that further work is necessary to reproduce the washing effects of natural wind and/or rain.
Citation
Service Life Prediction of Polymeric Materials: Reaching New Heights
Publisher Info
Elsevier, Cambridge, MA

Keywords

polycarbonate, poly(butylene terephthalate), poly(styrene-co-acrylonitrile), reciprocity, activation energy, humidity effects, xenon arc, correlation, outdoor exposure polycarbonate, poly(butylene terephthalate), SAN, reciprocity, activation energy, humidity effects, xenon arc, correlation, outdoor exposure polycarbonate, poly(butylene terephthalate), SAN, reciprocity, activation energy, humidity effects, xenon arc, correlation, outdoor exposure
Created August 4, 2020, Updated August 25, 2020