Degradation Mechanism of Ethylene-propylene-diene Terpolymer by zone in Aqueous Solution Satoshi MIWA 1, 2, Takako KIKUCHI 1, 2, Yoshito TAKE 1 and Keiji TANAKA 2 ( 1 Chemicals Evaluation and Research Institute, Japan, 1600, Shimo-takano, Sugito-machi, Kitakatsushika-gun, Saitama 345-0043, Japan; 2 Department of Automotive Science, Graduate School of Integrated Frontier Sciences, Kyushu University 744, Motooka, Nishi-ku, Fukuoka 819-0395, Japan) miwa-satoshi@ceri.jp The degradation of ethylene-propylene-diene terpolymer (EPDM) in ozone water has been investigated. The surface of EPDM specimen degraded rapidly in ozone water. It showed adherence after ozone water treatment, since the polymer near the surface decomposed. From Fourier transform infrared (FT-IR) spectroscopy, the aggregation structure near the surface of EPDM treated with ozone in aqueous solution was different from that treated with ozone in gas phase. This may be due to that the degradation of EPDM by ozone in aqueous solution was initiated by hydroxyl radical, which was generated by self-decomposition of ozone. Through nuclear magnetic resonance (NMR) spectroscopy, the detected structures from degraded EPDM after ozone water treatment agreed with the most probable structures, which may be produced by ozone water treatment. It was concluded that the degradation of EPDM proceeded in ozone water, regardless of its good ozone resistance in air, because hydroxyl radical caused the decomposition of EPDM, which was initiated from proton abstraction from saturated hydrogen carbon linkage of EPDM main chain. (Received on February 26, 2010) (Accetpted on July 22, 2010) Key Words
ML 2 3 valve 3 water treatment tank 3 killer ozonizer specimens flowmeter magnetic stirrer tank for 3 gas cooling glass filter (pore size : 40 μm) d J J
Tack strength / 10 5 Pa 4.0 3.0 2.0 1.0 0 0 40 80 120 Treatment time / h [I] [II] 160 ü é Absorbance / a.u. [I] [II] [III] [I] pristine [II] treated with ozone water [III] treated with ozone gas [IV] hydrated by 50 % H 2 S 4 [IV] M M M 3500 3000 2500 2000 1500 1000 Wavenumber / cm -1
50 % H 2 S 4 r. t., 168 h CH d L K J I H L K J H J J d d HGF EBA ENB 150 125 100 [I] 13 C NMR THF-d 8 L) J) K) THF-d 8 DEPT 90 220 180 140 100 60 [II] DEPT 135 200 175 150 125 100 δ / ppm 75 50 25 0 50 40 30 20 10 δ / ppm
D C I I AG G g b F f B d A c E E D ec a g cf d GAFB H Lag THF-d 8 THF-d 8 D) 13 C NMR C) g) f) e) B)-d) D)-e) F)-f) c) d) A)-c) b) a) C)-a) A) B) C) D) F) DEPT 90 DEPT 135 G) F) B) A) G)-b) G) 90 80 70 60 50 δ / ppm 40 30 20 10 THF-d 8
g) f) e) d) c) b) a) THF-d 8 A)-g) -g) g) f) e) d) c) b) B)-f) -c),d) -f) F)-d) G)-c) a) G)-a) A) B) F) G) a C G H b G E c g A G L E d f B F J e D K B f d F E J A g c G E K L ag AL L)-g) K)-g) J)-f) -b) K)-e) J)-d) L)-c) -a) THF-d 8 G)-b) G)-b) C C)-a) F)-f) J) B)-d) H CH C 2 CH 2 CH or C D)-e) K) C A)-c) J) K) L) L) C CH A)-c) 2 CH 2 H + acids scission ex. 2 tert-alcohols tert-alcohols ex. 2 scission + +
Trans. Faraday Soc zone: Sci. Eng. Nippon Gomu Kyokaishi Chem. Int. Ed. Engl Polym. Sci. U. S. S. R éenviron. Sci. Tech üéj. Phys. Chem üéj. Phys. Chem. Environ. Sci. Tech épolymer Macromolecules