Comparing Strategies for the Synthesis of Polyolefinic Thermoplastic Elastomers via Macromonomer Incorporation

Macro Reaction Engineering

2010

Two different modeling techniques, the method of moments and Monte Carlo simulation, were compared for propylene polymerization with coordination catalysts including a new mechanistic step, site transformation by electron donors. We used the models to show how the molecular weight and tacticity distributions of several poly(propylene) chain populations were affected by changing the concentration of hydrogen, electron donor, and propylene in the reactor, under steady‐state or dynamic operating conditions. The Monte Carlo simulation describes the molecular weight and tacticity distributions for the whole polymer and chain populations with distinct microstructural characteristics. We have also applied the Monte Carlo model to simulate the pentad sequence distributions and its equivalent 13C NMR spectra.

Section: Model Developmentmentioning

confidence: 99%

Section: Model Developmentmentioning

confidence: 99%

Mathematical Modeling of the Microstructure of Poly(propylene) Made with Ziegler‐Natta Catalysts in the Presence of Electron Donors

Alshaiban

Macro Reaction Engineering

2010

“…Simon and Soares 13 used a Monte Carlo model to describe the long‐chain branch formation in polyethylene made with a combination of single‐site catalysts. A Monte Carlo model was also used to analyze the microstructure of polyolefin thermoplastic elastomers made with two single‐site catalysts 14. Beigzadeh et al 15.…”

Section: Model Developmentmentioning

confidence: 99%

Simulation of Propylene Polymerization in Industrial Reactors Using Ziegler‐Natta Catalysts in the Presence of Electron Donors

Alshaiban

Macromolecular Symposia

2009

Heterogeneous Ziegler-Natta catalysts are still the most important catalysts for the industrial production of polyolefins, despite the discovery of high-activity metallocene systems in the eighties. Despite of their huge commercial importance, several aspects of Ziegler-Natta catalysts are still poorly understood from both qualitative and quantitative points of view. Especially for polypropylene, a very important factor controlling product quality is the effect of the electron donor used to modify the catalyst. In this manuscript we present, for the first time, a quantitative mathematical model that describes the effect of electron donors on the tacticity of polypropylene made with multiple-site type catalysts.

“…Monte Carlo models have also been used to describe the morphology of these heterogeneous copolymers in more details ( Figure 19). [44] Modeling the Effect of Dienes on LCB Distribution It seems evident from our previous discussion that, for all practical polymerization conditions, polymers made with either single or dual coordination polymerization catalysts will not have a large number of LCBs. Particularly, the branching structure will be very distinct from that of LDPE made with high-pressure free radical polymerization processes.…”

Section: Heterogeneous Branching With Dual Catalystsmentioning

confidence: 99%

“…Chain length distribution TPE chains with one (a) and two LCBs (b). [44] semi-batch reactor. It is instructive to notice how increasing diene content and polymerization time raises the LCB content of these polymers up to a point where gel formation is apparent.…”

Section: Heterogeneous Branching With Dual Catalystsmentioning

confidence: 99%

Polyolefins with Long Chain Branches Made with Single‐Site Coordination Catalysts: A Review of Mathematical Modeling Techniques for Polymer Microstructure

2004

Macro Materials & Eng

Summary: Single‐site coordination polymerization catalysts are considered one of the most important developments on the technology of olefin polymerization during the last two decades. Among the several new capabilities of these catalysts is the ability to produce polymer molecules having narrow molecular weight distribution and long chain branches. These advances in polymer synthesis have stimulated the development of mathematical models to describe and predict several features of their molecular architectures. Many modeling techniques have been used for this purpose, including instantaneous distributions, population balances, the method of moments, and Monte Carlo simulations. This article reviews the mathematical models developed over the last decade to quantify the microstructure of polymers made with single‐site catalysts with special emphasis on the mechanism of long chain branch formation by terminal branching. magnified image