Computational fluid dynamics (CFD) analysis of mixing in styrene polymerization

A styrene polymerization in a lab-scale CSTR equipped with a pitched blade turbine impeller was simulated using the computational fluid dynamics (CFD) approach. The impeller motion was integrated in the geometry using the multiple reference frame (MRF) technique. The presence of non-linear source term and the highly coupled nature of transport equations of the polymerization, made the convergence difficult to achieve. The effects of the impeller speed, the input-output locations and the residence time on the polymerization in the CSTR were investigated. The CFD simulation shows that good mixing remained limited to the impeller region. Regions far from the impeller remained unmixed due to high viscosity of the polymer mass. The path lines of the particles, released at the inlet, were also generated to analyze the reaction progress as the chemicals travel throughout the reactor. The monomer conversion computed using the CFD model was compared to data reported in the literature. Conversion predicted using the CFD model is in good agreement with that obtained from the CSTR model at low residence time. However, the CFD predicted coversions were higher than those calculated from the CSTR model, at high residence time. It was found that the input-output locations had significant effect on the conversion and the homogeneity in the CSTR.

Computational fluid dynamics (CFD) analysis of mixing in styrene polymerization

A styrene polymerization in a lab-scale CSTR equipped with a pitched blade turbine impeller was simulated using the computational fluid dynamics (CFD) approach. The impeller motion was integrated in the geometry using the multiple reference frame (MRF) technique. The presence of non-linear source term and the highly coupled nature of transport equations of the polymerization, made the convergence difficult to achieve. The effects of the impeller speed, the input-output locations and the residence time on the polymerization in the CSTR were investigated. The CFD simulation shows that good mixing remained limited to the impeller region. Regions far from the impeller remained unmixed due to high viscosity of the polymer mass. The path lines of the particles, released at the inlet, were also generated to analyze the reaction progress as the chemicals travel throughout the reactor. The monomer conversion computed using the CFD model was compared to data reported in the literature. Conversion predicted using the CFD model is in good agreement with that obtained from the CSTR model at low residence time. However, the CFD predicted coversions were higher than those calculated from the CSTR model, at high residence time. It was found that the input-output locations had significant effect on the conversion and the homogeneity in the CSTR.

EFFECT CONCENTRATION OF INITIATOR ON STYRENE POLYMERIZATION PROCESS

The article considers the effect concentration of initiator and temperature on the process of free-radical polymerization of styrene. A system of equations for calculating the optimal concentration of the initiator and equation for calculating the degree of polymerization were proposed. The results of this work can be applied in the production of polystyrene.

THE PROCESS OF STYRENE POLYMERIZATION UNDER ACOUSTICAL RADIATION

Cavitation treatment in the suspension polymerization of styrene leads to an increase in the yield of the finished product

Polystyrene Chain Growth Initiated from Dialkylzinc for Synthesis of Polyolefin-Polystyrene Block Copolymers

Polyolefins (POs) are the most abundant polymers. However, synthesis of PO-based block copolymers has only rarely been achieved. We aimed to synthesize various PO-based block copolymers by coordinative chain transfer polymerization (CCTP) followed by anionic polymerization in one-pot via conversion of the CCTP product (polyolefinyl)2Zn to polyolefinyl-Li. The addition of 2 equiv t-BuLi to (1-octyl)2Zn (a model compound of (polyolefinyl)2Zn) and selective removal or decomposition of (tBu)2Zn by evacuation or heating at 130 °C afforded 1-octyl-Li. Attempts to convert (polyolefinyl)2Zn to polyolefinyl-Li were unsuccessful. However, polystyrene (PS) chains were efficiently grown from (polyolefinyl)2Zn; the addition of styrene monomers after treatment with t-BuLi and pentamethyldiethylenetriamine (PMDTA) in the presence of residual olefin monomers afforded PO-block-PSs. Organolithium species that might be generated in the pot of t-BuLi, PMDTA, and olefin monomers, i.e., [Me2NCH2CH2N(Me)CH2CH2N(Me)CH2Li, Me2NCH2CH2N(Me)Li·(PMDTA), pentylallyl-Li⋅(PMDTA)], as well as PhLi⋅(PMDTA), were screened as initiators to grow PS chains from (1-hexyl)2Zn, as well as from (polyolefinyl)2Zn. Pentylallyl-Li⋅(PMDTA) was the best initiator. The Mn values increased substantially after the styrene polymerization with some generation of homo-PSs (27–29%). The Mn values of the extracted homo-PS suggested that PS chains were grown mainly from polyolefinyl groups in [(polyolefinyl)2(pentylallyl)Zn]−[Li⋅(PMDTA)]+ formed by pentylallyl-Li⋅(PMDTA) acting onto (polyolefinyl)2Zn.