Unsteady diffusion kinetics of Ziegler‐Natta heterogeneous catalyst polymerization, 4. Prediction of experimental results of propylene/ethylene/1‐hexadecene terpolymerization

Abstract

The prediction, based on unsteady diffusion kinetics, of the enhancement of reactivity and incorporation of 1-hexadecene in its copolymerization with propylene on adding a small amount of ethylene (increase from 5,2 mol-Vo to 10,8 mol-Yo when 2% of ethylene was added, and to 16,l mol-Yo when 5% was added) was verified in the terpolymerization of propylene/l-hexadecene/ ethylene on a commercial Solvay-type 6-TiC1, catalyst. The catalyst efficiency was thus also increased. These augmentations originate from the increase in diffusion coefficient of 1 -hemdecene at the catalyst surface when the P P crystallinity decreases on introduction of ethylene. Calculation based on unsteady diffusion kinetics showed that the order of diffusion coefficients ethylene > propylene > 1-hexadecene is reversed as the monomer concentration increases when the monomers are not at their equilibrium concentration. Sequence distribution as determined by means of I3C NMR revealed a tendency of blocky structure rather than a Bernoullian one. The terpolymer compositions obtained by means of an IR method developed in this work conform rather well with the NMR results. Results in this work not only support the unsteady diffusion kinetics but also provide a new route to prepare olefinic copolymer rubbers with heterogeneous titanium catalysts. a) Part 3: cf. ref. '). b, Present address:

Co- and terpolymerization of ethylene, propylene, and higher ?-olefins with high propylene contents using metallocene catalysts

“…Other researchers have demonstrated that unsteady diffusion kinetics can predict that the reactivity of 1‐hexadecene with propylene in a heterogeneous Ziegler–Natta copolymerization should increase by two to three times by adding a small amount of ethylene 11. Those researchers had found that terpolymers with 2–10 mol % of 1‐hexadecene as well as small amounts of ethylene incorporated (2–10 mol %) show both lower mps and crystallinity than corresponding copolymers (up to 5–10 °C in T m and five to eight times in crystallinity values).…”

FTIR, 13C NMR, and GPC analysis of high‐propylene content co‐ and terpolymers with ethylene and higher α‐olefins synthesized with EtInd2ZrCl2/MAO

“…For these researchers, in the terpolymerization of ethylene/propylene/1‐hexadecene the diffusion coefficient of monomer is in the following order: ethylene > propylene > 1‐hexadecene. Then, the extent of the increase in monomer concentration, if it is not in equilibrium, will be 1‐hexadecene > propylene > ethylene 28…”

Intramolecular branching distributions in metallocene short‐chain branched polyethylenes examined by crystallization and annealing at high pressure

“…The relation between these can be determined analytically using techniques such as temperature rising elution fractionation (TREF)7 and the more recent crystallization analysis fractionation (CRYSTAF) 8–10. The great variability observed in such work is attributed to great variation in different catalyst sites associated with Z–N materials,11, 12 which has been attributed to variations in the diffusion of the different monomers to active sites 13, 14. Such variation can be deliberately introduced15 and is particularly apparent in VLDPEs, which are in effect a reactor blend of different materials ranging from high‐density PE to uncrystallizable rubber‐like material, and where comparing fractionation by direct extraction (according to molar mass) and by crystallization/dissolution (similar to TREF) shows a strong correlation between branch content and molar mass 6.…”