Influence of the catalyst matrix structure of the supported Ziegler-Natta catalysts on the homo- and copolymerization of olefins

Meshkova, I. N.; Ushakova, T. M.; Gul'tseva, N. M.; Larichev, M. N.; Ladygina, T. A.; Кудинова, О. И.

doi:10.1007/s002890050068

Cited by 5 publications

(3 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is what is known as the comonomer effect. The phenomenon has been reported in Ziegler-Natta, Phillips, and metallocene catalysts with a large variety of comonomers [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] and great concern exists in explaining its true nature, since it has important consequences from a production point of view [16].…”

Section: Introductionmentioning

confidence: 82%

“…In fact, many works agree with this assumption as a crucial piece in the puzzle [5,10,11,12,15,21,23,24,27,29,45,46,47,48,49]. For example, fracturing of inorganic particles and polymer aggregates in heterogeneous and homogeneous catalysis, respectively, has been claimed to exert a primary role [1,2,34,36], however the fact that the comonomer effect has been observed in systems both without particle fragmentation and completely dissolved suggests that this factor is not essential.…”

Section: Introductionmentioning

confidence: 99%

“…Many authors have claimed solubility enhancement of copolymer chains and subsequent improvement in mass transfer processes as the key factor in Ziegler-Natta and supported metallocene catalysts [2,7,15,22,24,25,26,31,34,35,36,37,38,39,40,41,42,43], however although an easier diffusion of the monomer through less crystalline phases may contribute to a rate enhancement, no satisfactory correlation has been found with crystallinity degree or copolymer solubility [44].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A New Insight into the Comonomer Effect through NMR Analysis in Metallocene Catalysed Propene–co–1-Nonene Copolymers

García‐Peñas

Barranco‐García

et al. 2019

Polymers

View full text Add to dashboard Cite

The “comonomer effect” is an intriguing kinetic phenomenon in olefin copolymerization that still remains without a detailed explanation. It typically relates to the rate of enhancement undergone in ethylene and propene catalytic polymerization just by adding small fractions of an alpha-olefin. The difficulty lies in the fact that changes caused by the presence of the comonomer in reaction parameters are so conspicuous that it is really difficult to pin down which of them is the primary cause and which ones are side factors with marginal contribution to the phenomenon. Recent investigations point to the modification of the catalyst active sites as the main driving factor. In this work, the comonomer effect in the metallocene copolymerization of propene and 1-nonene is analysed and correlated to the comonomer role in the termination of the chain-growing process. The associated termination mechanisms involved furnish most of chain-free active sites, in which the selective interaction of the comonomer was proposed to trigger the insertion of monomers. A thorough characterisation of chain-end groups by means of the 1H NMR technique allows for detailing of specific transfer processes, ascribed to comonomer insertions, as well as evidencing the influence of the growing chain’s microstructure over the different termination processes available.

show abstract