Effect of Reactor Conditions and Catalyst Design on Rheological Behavior of Polymers Produced in Catalytic Olefin Polymerization FBRs
Advancing the chemical engineering fundamentals
Rheology (T2-4)
Keywords: Polyethylene, Molecular Weight Distribution, Viscoelastic Properties, Modeling, Fluidized bed Reactor
In the manufacturing of polyolefins it is of profound importance the control of molecular properties (e.g., MWD, CCD, etc.) to ensure the production of polymers with desired molecular characteristics that determine the molecular architecture of the polymer chains. In the present study, a fundamental rheological model is developed to investigate the effects of catalyst type, and reactor operating conditions on the polymer end-use properties produced in an industrial gas-phase olefin polymerization FBR. The rheological model includes reptation and Rouse relaxation terms. A multi-scale, integrated dynamic model is developed to assess the effect of polymer distributed properties on the rheological behavior of PE produced in a catalytic Ziegler-Natta gas-phase olefin copolymerization FBR. The proposed multi-scale reactor description comprises a detailed kinetic model for the prediction of molecular weight distribution (MWD) and copolymer composition distribution (CCD), a random pore polymeric flow model (RPPFM) to follow the growth of individual polymer particles in the reactor and a population balance model to follow the dynamic evolution of PSD. Numerical simulations are carried out, using the multi-scale model, to investigate the effect of reactor conditions, polymer crystallinity and catalyst design specifications on the distributed molecular properties as well as on the rheological behavior of PE. It is established that the proposed rheological model can provide quantitative predictions of polymer end-use properties (e.g., melting temperature, impact resistance, tensile strength, MFI, shear viscosity, etc.) in terms of the molecular properties (e.g., MWD, CCD, etc.). It is demonstrated that the present modeling approach offers a powerful product design tool since it can provide quantitative information on the effect of molecular architecture on PE rheological properties.
Presented Thursday 20, 14:40 to 15:00, in session Rheology (T2-4).
