In:
Journal of Polymer Science Part B: Polymer Physics, Wiley, Vol. 28, No. 13 ( 1990-12), p. 2509-2526
Abstract:
For a series of homogeneous ethylene‐propylene copolymers with mole fraction ethylene ( x 1 ) ranging between 0.40 and 0.85, the inversion (I) independent propagation probabilities ( P ij s) and reactivity ratios ( r ij s) and the methylene, ethylene, and propylene sequence length distributions have been determined from 13 C nuclear magnetic resonance (NMR) data, using a first‐order Markovian terpolymer [ethylene (1), inverted propylene (2), and normal propylene (3)] model. For each sample, the limiting values of I ( I min , I max ) are given. Calculations of the common parameters for 19 samples show that the polymerization direction characterized by the r set and I is statistically more probable than the opposite direction, which is characterized by the r ′ set and I ′. Further, I = I min appears to be close to the most probable value of I . The resulting r set is r 12 = 119, r 13 = 19.7 and, for I = I min , r 21 = 0, r 31 = 0.034, r 32 = 2.98. In the limited range 0.60 〈 x 1 〈 0.85, there appears to be no preference for either polymerization direction, so that the solutions characterized by the r set and I = I min and by the r ′‐set and I = I ′ max , respectively, are about equally probable. If the copolymer reactivity ratios r e and r p are defined in the usual manner, it follows that for the limited range r e = 17. In the model used here, r p is found to be dependent on the ethylene‐propylene ratio in the reactor. Nevertheless, it can be stated that r p ≅ 0.029 and r e r p ≅ 0.50.
Type of Medium:
Online Resource
ISSN:
0887-6266
,
1099-0488
DOI:
10.1002/polb.09.v28:13
DOI:
10.1002/polb.1990.090281305
Language:
English
Publisher:
Wiley
Publication Date:
1990
detail.hit.zdb_id:
1473448-5
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