|Discoloration Mechanism of Thermoplastic Elastomer
gStyrene-Butadiene-Styrene Block CopolymerhProducts
Panwashlet Co., Ltd., Material Reseach Sec., Kokuraminami-ku, Kitakyusyu, Japan
Chemicals Evaluation and Research Institute, Japan, Kitakatsushika-gun, Saitama
Department of Materials Science, Graduate School of Science and Technology, Nagasaki University, Nagasaki, Japan
Nippon Gomu Kyokaishi,(2005),78(11),413-418 Original Paper in Japanese
Discoloration mechanism of styrene-butadiene-styrene block copolymer (SBS) containing phenolic antioxidants by human excrement and urine was studied. The phenolic antioxidants react with SBS to give bright pink, discolored products. They were analyzed by color-difference measurement, FT-IR, TOF-SIMS, and ESR. Products of high activation state were formed on the discolored surface by reaction of the phenolic antioxidant with nitrogen compounds and metallic elements that were metabolized from a human body.
The colored substance is a 3,3',5,5'-tetra-tert-butyl-4,4'-stilbenequinone derivative. This discoloration is disappeared by the ative. This discoloration is disappeared by the addition of the phosphoric antioxidant to SBS products.
(Received on December 27, 2004)
(Accepted on September 16, 2005)
Thermoplastic elastomer, Styrene-butadiene-styrene block copolymer, Phenolic antioxidant, Elucidation of discoloration mechanism, 3,3',5,5'-tetra-tert-butyl-4,4'-stilbenequinone, TOF-SIMS, ESR