Korean Journal of Chemical Engineering, Vol.25, No.6, 1532-1538, November, 2008
Photochemical reduction of molecular weight and number of double bonds in natural rubber film
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Abstract.Natural rubber (NR) can be degraded depending on various factors such as heat, mechanical force, chemical reaction, and light. Light is a very interesting factor because it can cause the NR to degrade under low temperature and pressure. The photo-degradation of NR films was carried out to investigate the effects of the light and the temperature on the reduction of the weight-average molecular weight (Mw) and the double bonds in the NR films. The NR films, with and without catalysts, titanium dioxide (TiO2), and potassium persulfate (K2S2O8), were exposed to light from a mercury light bulb at 7,000 and 36,000 lux, and at the temperature of 25 ℃ and 80 ℃ for 192 hrs. After exposure, the Mw of the NR films was analyzed by gel permeation chromatography (GPC). Changes in the Mw were used to construct a kinetic model for the process, (1/Mw)=(1/Mw0)+(kt/2M0) where k is the rate constant, and M0 is the Mw of the monomer unit. The linear relationship between 1/Mw and time suggested pseudo first-order processes with random scission. The Mw distribution information from the GPC was used to calculate the number of double bonds in the NR films. The trend of the double bonds reduction curves was quite similar to the result obtained from the calculation from the FTIR spectra. This indicated that this calculation method might possibly be another alternative way to obtain the
number of double bonds in the NR.
- Kelen T, Polymer degradation, Van Nostrand Reinhold, New York (1983)
- Adam C, Lacoste J, Lemaire J, Polym. Degrad. Stab., 32, 51 (1991)
- Newman CR, Forciniti D, Ind. Eng. Chem. Res., 40(15), 3346 (2001)
- Copinet A, Bertran C, Govindin S, Coma V, Couturier Y, Chemosphere, 55, 763 (2004)
- Naddeo C, Guadagno L, Vittoria V, Polym. Degrad. Stab., 85, 1009 (2004)
- Santos KAM, Suarez PAZ, Rubim JC, Polym. Degrad. Stab., 90, 34 (2005)
- Gijsman J, Meijers G, Vitae G, Polym. Degrad. Stab., 65, 433 (1999)
- Maillo CM, White JR, Plast. Rubb. Comp., 28, 277 (1999)
- Andrady AL, Hamid SH, Hu X, Torikai A, J. Photochem. Photobio. B., 46, 96 (1998)
- Arabatzis IM, Stergiopoulos T, Bernard MC, Labou D, Neophytides SG, Falaras P, Appl. Catal. B: Environ., 42(2), 187 (2003)
- Zhang TY, Oyama T, Horikoshi S, Zhao JC, Serpone N, Hidaka H, Appl. Catal. B: Environ., 42(1), 13 (2003)
- Zhang L, Zhu YF, He Y, Li W, Sun HB, Appl. Catal. B: Environ., 40(4), 287 (2003)
- Sakkas VA, Arabatzis IM, Konstantinou IK, Dimou AD, Albanis TA, Falaras P, Appl. Catal. B: Environ., 49(3), 195 (2004)
- Kim IK, Ha HJ, Lee SK, Lee JK, Korean J. Chem. Eng., 22(3), 382 (2005)
- Yoa SJ, Cho YS, Kim JH, Korean J. Chem. Eng., 22(3), 364 (2005)
- Thiruvenkatachari R, Kwon TO, Moon IS, Korean J. Chem. Eng., 22(6), 938 (2005)
- Kim KN, Hoffmann MR, Korean J. Chem. Eng., 25(1), 89 (2008)
- Park DR, Ahn BJ, Park HS, Yamashita H, Anpo M, Korean J. Chem. Eng., 18(6), 930 (2001)
- Cho S, Choi W, J. Photochem. Photobio. A., 143, 221 (2001)
- Shang J, Chai M, Zhu Y, J. Solid. State. Chem., 174, 104 (2003)
- Shang J, Chai M, Zhu Y, Envi. Sci. Tech., 37, 4493 (2003)
- Kubota H, Hariya Y, Kuroda S, Kondo T, Polym. Degrad. Stab., 72, 223 (2001)
- Roubroeks JP, Andersson R, Mastromauro DI, Christensen BE, Aman P, Carbo. Polm., 46, 275 (2001)
- Tanford C, Physical chemistry of macromolecules, Wiley, New York (1961)
- Allcock HR, Lampe FW, Mark JE, Contemporary polymerc chemistry, Pearson Education, New Jersey (2003)
- Turton TJ, White JR, Polym. Degrad. Stab., 74, 559 (2001)