Particle Growth during the Polymerization of Olefins on Supported Catalysts. Part 2: Current Experimental Understanding and Modeling Progresses on Particle Fragmentation, Growth, and Morphology Development

Abstract

The morphology of the growing polymer particles is important in olefin polymerisation on supported catalysts. It has a significant impact on the rate of mass and energy transport, and consequently on the polymerisation rate, comonomer incorporation, and the molecular weight distribution. The ability to quantify the evolution of morphology during the polymerisation process à priori would therefore be quite useful. The morphology itself is a direct product of the fragmentation step and concurrent/subsequent expansion of the particle, both caused by the build‐up and dissipation of hydraulic forces due to the accumulation of polymer in the particle. It is influenced by the initial morphology of the support, as well as the reaction conditions and local polymer properties. The single particle models developed to describe the morphology evolution in a growing particle are reviewed here. The main assumptions, abilities, and limitations of the models are evaluated and the issues which face developing a completely predictive model are finally discussed. Despite some very interesting attempts at morphology modelling in recent years, significant progress still needs to be made in order to develop a fully predictive model of the sort.

Advances in Mathematical Modeling of Gas-Phase Olefin Polymerization

“…The utilization of a metallocene catalyst system, Ziegler-Natta catalyst system, Fujita group Invented (FI) catalyst system, and oxide-supported surface organometallic complexes in olefin polymerization synthesis. [6,[12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] 6. Process Modeling…”

“…The implementation of mathematical models, namely macroscale modeling, mesoscale modeling, microscale modeling, single particle modeling, computational fluids dynamic modeling, microelements modeling, 2D finite element modeling, single pore modeling, and parti-level fragmentation modeling to determine the properties of the polyolefin, and the mass and heat transfer phenomena during the polymerization process. [8,11,12,22,[31][32][33][34] 7. Quality Control Different types of analysis such as nuclear magnetic resonance (NMR), temperature rising elution fractionation (TREF), gel permeation chromatography (GPC), rheological characterization (zero shear viscosity, zero shear viscosity, shear thinning behavior, dynamic modulus, loss angle, Van-Gurp-Palmen plot, Cole-Cole plot, activation energy, thermorheological complexity, strain-hardening effect, relaxation time, damping function, nonlinear dynamical oscillatory shear, and long-chain branching index), dynamic mechanical analysis, differential scanning calorimeter, neutron scattering, and molecular topology fractionation.…”

Dynamic simulation and control of two-series industrial reactors producing linear low-density polyethylene

“…Directly after the reactive species reach an active site, the polymer layer is formed over the active site, inside the porous space of the supported catalyst. By accumulation of polymer at the active sites, the inorganic phase suffers a local build-up of stress that causes weak points of the solid structure to break, and the support starts to fragment into a series of unconnected mineral substructures maintained by a polymer phase [23]. The prepolymerization step gives a prepolymer particle the ability to mechanically withstand, or decreases the reaction peak by generating an amount of stress sufficient for the particles to fragment, but not so much and not too quickly that they be disintegrated [24].…”

Particle morphology, structure and properties of nascent ultra-high molecular weight polyethylene

“…A good particle morphology from an industrial perspective usually means spherical shape, narrow particle size distribution, high bulk density, controlled degree of porosity and internal composition, etc. [ 2 , 3 ]. Several models have been proposed over the years to elucidate the particle growth mechanism, among which the solid core model, flow model and the multigrain model [ 4 – 6 ] are the most popular and widely used.…”

“…In addition, polymerization conditions, especially in the initial stages of polymerization, also play a key role in controlling the particle morphology. Previous studies [ 2 , 14 , 15 ] have proved that using pre-polymerization technique, polymerization occurs under milder condition, and the initial particle growth could be better controlled, which influences the final particle morphology [ 16 ]. Besides, the polymer microstructure is strongly dependent on the interaction between polymerization and crystallization over time [ 2 ], which in turn affect the morphology of polymer particles.…”