1. © Nonisothermal, Uncontrolled Homo- And Copolymerization Of Ethylene Using Selected Zirconocenes Atiqullah, M; Hammawa, H; Akhtar, MN; Khan, JH; Hamid, H JOHN WILEY SONS INC, JOURNAL OF APPLIED POLYMER SCIENCE; pp: 137-147; Vol: 70 King Fahd University of Petroleum & Minerals http://www.kfupm.edu.sa Summary Nonisothermal, uncontrolled polymerization, conducted in varying mixing regimes, offered a facile methodology to evaluate the influence of several important process development factors such as mixing, reaction exotherm, and thermal perturbations on the catalytic activity and kinetic stability, polymerization performance, and properties of the resulting polymers. Ethylene was homo- and copolymerized with hexene-1 under varying impeller speeds thence, thermal perturbations), using Ind(2)ZrCl(2) and Et(Ind)(2)ZrCl2 and the MAO cocatalyst. With respect to the effects of the above process development factors, the following was observed: The reaction exotherm profiles, tracing the polymerization history, qualitatively represented the kinetic profile and the catalytic stability. The unbridged Ind(2)ZrCl(2) was shown to be more stable than the bridged Et(Ind)(2)ZrCl2. With change in the level of stirring from a diffusion-controlled regime to a nondiffusion-controlled, external gas-liquid mass- transfer resistance-free one, the reaction exotherm and the run time-average catalytic activity increased. So far as the influence of the chiral versus the achiral zirconocene structure is concerned, the copolymer composition distribution and soluble fraction generated by chiral Et(Ind)(2)ZrCl2 were more sensitive to the mixing conditions and thermal perturbations than were those produced by achiral Ind(2)ZrCl(2). Et(Ind)(2)ZrCl2 produced higher molecular weight backbones, incorporated more hexene-1 and chain branching, and introduced less crystallinity in the copolymers than did Ind(2)ZrCl(2). The influence of Ind(2)ZrCl(2) on higher-weight Copyright: King Fahd University of Petroleum & Minerals; http://www.kfupm.edu.sa

2. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32. 33. 34. © homopolymer backbones was opposite to that of Et(Ind)(2)ZrCl2. Incorporation of hexene-1 significantly decreased the average molecular weights and density and increased the run-time-dependent average catalyst activity. A positive comonomer effect took place. The bulk polymer properties did not critically depend on the mixing state. Thermal perturbations broadened the polydispersity index. (C) 1998 John Wiley Sons, Inc. J Appl Polym Sci 70: 137-147, 1998. References: *ASTM, 1985, D1505 ASTM, P466 *ASTM, 1986, D2238 ASTM, P227 *RES I, 1991, OV REC TECHN DEV MAN, P5 *RES I, 1996, DEV HET MET CAT OL P ATIQULLAH M, 1990, CHEM ENG SCI, V45, P1267 ATIQULLAH M, 1992, J APPL POLYM SCI, V46, P879 ATIQULLAH M, 1993, EUR POLYM J, V29, P1581 ATIQULLAH M, 1993, POLYM ENG SCI, V33, P1644 BOHM LL, 1978, POLYMER, V19, P553 CANICH JAM, 1991, 0420436, EP CANICH JAM, 1991, 04257, WO CHIEN JCW, 1988, J POLYM SCI A, V26, P2369 CHIEN JCW, 1988, J POLYM SCI A, V26, P3089 CHIEN JCW, 1991, J POLYM SCI POL CHEM, V29, P1585 CHIEN JCW, 1993, J POLYM SCI POL CHEM, V31, P227 GIANNETTI E, 1985, J POLYM SCI POL CHEM, V23, P2117 HEILAND K, 1992, MAKROMOL CHEM, V193, P601 KAMINSKY W, 1988, POLYHEDRON, V7, P2375 KIM I, 1990, J APPL POLYM SCI, V39, P837 KIM I, 1994, J APPL POLYM SCI, V52, P1739 KOIVUMAKI J, 1993, MACROMOLECULES, V26, P5535 KULIN LI, 1988, PURE APPL CHEM, V60, P1404 LEE IM, 1992, ORGANOMETALLICS, V11, P2115 LEHTINEN C, 1997, EUR POLYM J, V33, P115 MONRABAL B, 1994, J APPL POLYM SCI, V52, P491 MONRABAL B, 1996, POLYM CHAR MONRABAL B, 1997, COMMUNICATION FEB SCHMIDT GF, 1988, TRANSITION METAL CAT, P151 SEPPALA JV, 1985, J APPL POLYM SCI, V30, P3545 SPALECK W, 1990, 2017190, CAN TOSUN G, 1992, AICHE J, V38, P425 TURNER HW, 1987, 0226463, EP TURNER HW, 1987, 03604, WO UOZUMI T, 1992, MAKROMOL CHEM, V193, P823 Copyright: King Fahd University of Petroleum & Minerals; http://www.kfupm.edu.sa

3. 35. 36. © WINTER A, 1990, 39056, AU WUNDERLICH B, 1967, J POLYM SCI A2, V5, P987 For pre-prints please write to: matiq@kfupm.edu.sa Copyright: King Fahd University of Petroleum & Minerals; http://www.kfupm.edu.sa