Laboratory accelerated and natural weathering of styrene–ethylene–butylene–styrene (SEBS) block copolymer

• Published in: Polymer degradation and stability Vol. 96; no. 6; pp. 1104 - 1110
• Main Authors: White, C.C., Tan, K.T., Hunston, D.L., Nguyen, T., Benatti, D.J., Stanley, D., Chin, J.W.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-06-2011; Elsevier
• Subjects: Ageing; Aging; Applied sciences; Block copolymers; composite polymers; Degradation; Exact sciences and technology; Indoor; Infrared spectroscopy; Outdoor; Outdoor exposure; Photooxidation; Physical properties; Polymer industry, paints, wood; Properties and testing; Relative humidity; SEBS; synergism; Technology of polymers; temperature; Thermoplastic elastomers; Weathering; Maryland; Degradation; Aging; Weathering; Thermoplastic elastomers; Outdoor exposure; SEBS; Thermal ageing; Temperature effect; Thermoplastic rubber; Experimental study; Triblock copolymer; Ultraviolet radiation; Humidity effect; Visible radiation; Reaction mechanism; Photochemical stability; Artificial ageing; Fourier-transformed infrared spectrometry; Exposure time; Photochemical degradation
• ISSN: 0141-3910; 1873-2321
• DOI: 10.1016/j.polymdegradstab.2011.03.003

Indoor accelerated and outdoor weathering of polystyrene-
b-(ethylene-
co-butylene)-
b-styrene (SEBS) was studied by infrared spectroscopy. Accelerated conditions involved simultaneous exposure of specimens to ultraviolet–visible radiation between 295 nm and 450 nm and each of four temperature/relative humidity (RH) environments, i.e., (a) 30 °C ± 1 °C at <1% RH, (b) 30 °C ± 1 °C at 80% RH, (c) 55 °C ± 1 °C at <1% RH, and (d) 55 °C ± 1 °C at 80% RH. Outdoor exposure was conducted in Gaithersburg, MD, in two different time periods. Similar photooxidative mechanisms were operative under all conditions. In the case of indoor accelerated exposure, the rate of photooxidation was found to depend strongly on temperature. Unlike the exposure at 55 °C, moisture-assisted photooxidation was insignificant at 30 °C. A quantitative study on the synergistic effect of environmental stressors revealed that the degrading effect of combined temperature and moisture on photooxidation was greater than the sum of the two effects exerted independently. Outdoor weathered specimens exhibited significantly slower photooxidation. Acceleration of photooxidation ranged from 2.5 to 10 times in comparison to the outdoor exposure, depending on the indoor accelerated conditions.