Gelation Phenomenon Observed in EPDM Compound with Carbon Black Hidenari NAKAHAMAI and Masaaki KAWASAKII (1Functional Polymeric Materials Laboratory,

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1 Gelation Phenomenon Observed in EPDM Compound with Carbon Black Hidenari NAKAHAMAI and Masaaki KAWASAKII (1Functional Polymeric Materials Laboratory, Mitsui Chemicals, Inc. 3, Chigusa-Kaigan, Ichihara, Chiba , Japan), Takashi MISHIMA2 (2Functional Polymeric Materials Laboratory, Mitsui Chemicals, Inc., , Nagaura, Sodegaura, Chiba , Japan) The phenomena of gelation observed in EPDM compounds with carbon black are known as being troublesome during the processing of rubber. In addition, it is mysterious that the gelation disappears after processing and suddenly appears again. We proposed a new index related to the phenomenon of gelation observed in EPDM compounds. That is, apparent free energy of activation (Ea) derived from reological tests is introduced as the index. Ea is calculated from the Arrhenius equation of shift factor, at, which is obtained from the temperature-dependence of complex viscosities. Two types of EPDM compounds were prepared; one whose gelation increased with increased mixing time, and another, which did not show the gelation owing to the addition of bis-3-(triethoxysilylpropyl)tetrasulfane (TESPT). Ean and Eao, the free energy of activation for both compounds, respectively, were obtained. The degree of gelation is defined as 100 (Eao-Ean)/Eao. Taking into account the degree of gelation defined above, rubber extrusion and rubber properties were studied. The dieswell decreased with the increase in mixing time, and the elongation of vulcanized EPDM also had the same tendency. Changes in these phenomena were proportional to the degree of the gelation index. Interestingly, a middle- T2 value measured by pulsed NMR decreased with the decrease in Ean. As a conclusion, the Ea value may be an effective index to determine the phenomena of gelation observed in EPDM compounds with carbon black. (Received on November 26, 2004). (Accepted on August 9, 2005) Key Words : Black scorch, Dieswell, Filler dispersion index, EPDM, Pulsed NMR, Spin-spin relaxation time, Mixing method, Bound rubber

2 Table 1 Compound formulations Table 2 Compound formulations

3 Figure 1 Mooney viscosity vs. testing time for EPDM compounds with carbon black. Compound 1 with 4 min of mixing (A) ; 5 min of mixing (B) ; 9 min of mixing (C) ; 15 min of mixing (D), Compound 2 with 15 min of mixing (H). 13) 407

4 Table 3 Activation energy of materials with various mixing times Figure 2 Log-log plots of complex viscosity vs. frequency for compound 2, o: at 170 C, p: at 190 C, q: at 210 t H of Figure 3 Plots of In (at) against (T-1- To-i) used for the calculation of Ed. H, compound 2 with 15 min mixing; D, compound 1 with 15 min mixing. Table 4 Activation energy of materials with various CB contents Figure 4 Relationship between Ea and carbon black loading. Compound 5-9 with 2Omin of mixing( ); compound 1 with 4 min of mixing (A) ; 5 min of mixing (B) ; 9 min of mixing (C) ;15 min of mixing (D), Compound 2 with 15 min of mixing (H). 408 (14)

5 Table 5 Degree of gelation calculated by equation (5) Figure 6 Relationship between Ea and dieswell. LII: compound 1, A: compound 2 Figure 5 Relationship between dieswell and mixing time. LI: compound 1, L.: compound 2, ~: compound 3 Figure 7 Relationship between dieswell and Mooney viscosity at 5Omin. Compound 1 with 4 min of mixing (A) ; 5 min of mixing (B) ; 9 min of mixing (C) ;15 min of mixing (D). ( 15) 409

6 Table 6 Relaxation time T2 and fraction of T2 at 60 t Figure 8 Relationship between Ea and T2m. LII: compound 1, A: compound (16)

7 Table 7 Compound properties affected by degreee of gelation Figure 9 Effect of filler dispersion in vulcanized EPDM on the dependency of E upon strain amplitude at 25 C, 10 Hz. EPDM compound 3: LI, 4 min of mixing;, 5 min of mixing; A 9 min of mixing; /, 15 min of mixing

8 References 1) Kremers, A., Krusche, A., Haberstroh, E.: Macromol. Mater. Eng., 284, 70 (2000) 2 ) Nakajima, N.:"The Science and Practice of Rubber Mixing", RAPRA Technology, UK, p.35 (2000) 3 ) Clarke, J., Freakley, R.K.: Rubber Chem. Technol., 67, 700 (1994) 4 ) Freakley, P.K., Idris, WY. Wan.: Rubber Chem. Technol., 52, 134 (1979) 5 ) Miyasaka, K.: Preprints of the 71St Gomu Gijutsu Symposium, p.10 (2000) 6 ) Takatsugi, H.: Nippon Gomu Kyokaishi, 76, 192 (2003) 7 ) Zhang, X., Whitehouse, R., Liauw, C.:"Compatibility of Carbon Blacks with Typical EPDM Extrusion Compounds: Phenomenon and Root Causes Paper No.43, IRC'97 (1997) 8 ) Daniel, C., Pillow J. G.:"Black Scorch in EPDM Compounds p.l, JREC'99 (1999) 9 ) Goto, H.: Nippon Gomu Kyokaishi, 71, 340 (1998) 10) Nakahama, H., Mishima, T.: Nippon Gomu Kyokaishi, 76, 149 (2003) 11) Satoyoshi, K.: 60th Gomu Neri Kenkyukai, P.10 (2001) 12) Nakahama, H., Hosoya, M., Kawasaki, M.: US Patent B1 (2000) 13) Kaufmann, S., Slichter, W. P., Davis, D. D.: J. Polym. Sci., A-2, 9, 829 (1971) 14) Fujimoto, K., Nishi, T.: Nippon Gomu Kyokaishi, 43, 54 (1970) 15) Sasaki, K.: Nippon Gomu Kyokaishi, 65, 353 (1992) 16) Nishi, T.: J. Polym. Sci., Polym. Phys.,12, 685 (1974) 17) Gessler, A. M.: Rubber Chem. Technol., 43, 943 (1970) 18) Hess, W. M., Chirico, V. E., Burgess, K. A.: Kaut.Gummi Kunst., 26, 334 (1973)

474 Nippon Shokuhin Kagaku Kogaku Kaishi Vol. /-, No.3,.1..2* (,**0) 24 Measurement of Deterioration of Frying Oil Using Electrical Properties Yoshio

474 Nippon Shokuhin Kagaku Kogaku Kaishi Vol. / No.3.1..2 (0) 24 Measurement of Deterioration of Frying Oil Using Electrical Properties Yoshio Hagura Yoshihiro Sasaki and Kanichi Suzuki Graduate School