In:
Journal of Polymer Science Part C: Polymer Symposia, Wiley, Vol. 23, No. 2 ( 1968-01), p. 453-459
Abstract:
To clarify the stereospecificity of Natta‐type catalysts, the temperature dependence of the isotacticity of a polypropylene has been investigated by using H‐type or A‐type TiCl 3 with Al(C 2 H 5 ) 3 or Al(C 2 H 5 ) 2 Cl in a study of the kinetic behavior of the polymerization under the conditions T = 30–75°C., P ≈︁ 1 atm., and [Al]/[Ti] = 1. With the use of Al(C 2 H 5 ) 3 the isotacticity increases with a rise in polymerization temperature, and it approaches that of Al(C 2 H 5 ) 2 Cl, which is almost independent of the polymerization temperature. On the other hand, with the use of Al(C 2 H 5 ) 3 the number of the polymerization centers decreases with a rise in temperature, while that with Al(C 2 H 5 ) 2 Cl remains unchanged. To explain these results, two kinds of polymerization center have been proposed; one is stable at any temperature and produces a higher‐isotacticity polymer, and the other is stable at the higher temperatures and produces a lowerisotacticity polymer. Some solvent effect of the isotacticity has been observed with the use of A‐TiCl 3 . The isotacticity with A‐TiCl 3 decreases by several per cent when n ‐heptane is used instead of toluene. This solvent effect has been explained on the basis of the existence of a considerable amount of AlCl 3 in A‐TiCl 3 .
Type of Medium:
Online Resource
ISSN:
0449-2994
,
1935-3065
DOI:
10.1002/polc.5070230203
Language:
English
Publisher:
Wiley
Publication Date:
1968
detail.hit.zdb_id:
221074-5
