Modeling of Polymerization Kinetics

A polymerization kinetic model is a very useful tool to quantify the polymerization rate phenomena and to predict the resulting polymer properties. To develop a kinetic model for SPS polymerization, the following kinetic scheme that has been well accepted for many metallocene catalyzed styrene polymerization systems [6,8,9] is employed. 

To calculate the molecular weight averages, the polymer molecular moment equations can be derived with the k-th molecular weight moments of live and 

The first three leading molecular weight moment equations are derived as follows. 

Number-average and weight-average molecular weights are calculated using the following equations  

The single-site kinetic model presented in the above can be easily modified for a real polymerization process where site heterogeneity often occurs when supported onto a catalyst support material because of nonuniform surface structure of the catalyst support. 

---

GARCIA-RUBIO AND MEHTA Modeling of Polymerization Kinetics... 

Solutions of Eqns. 32 through 35 on an analog computer are shown in Fig. 6 for the case of polymerization in a closed system. The plots of rp(t) and p(t) are seen to be in qualitative agreement with the experimental observations shown in Fig. 7. The model of polymerization kinetics was also found to provide curves of rp versus discharge current density and monomer flow rate which were consistent qualitatively with the experimentally observed results. 

Mathematical modeling of polymerization kinetics, including its application for the verification of kinetic schemes and the values of kinetic constants, as well as in the design of industrial processes. 

MATHEMATICAL MODELLING OF POLYMERIZATION KINETICS Table 3.1 A table of generating functions... 

An lUPAC task group Towards a Holistic Mechanistic Model for RAFT Polymerizations Dithiobenzoates as Mediating Agents was formed in 2005 rmder the auspices of the lUPAC Subcommittee on Modeling of Polymerization Kinetics and Processes. This dilemma paper strmmarized the current situation with respect to the polymerization kinetics, possible side reactions, and mechanisms for retcirdation. ... 

A 12-liter twin-shaft batch kneader reactor was used to carry out an exothermic bulk polymerization. Process data was measured and polymer samples were analyzed for conversion so that models of polymerization kinetics, shaft torque, and overall heat transfer could be developed. These models were used to predict the performance of a 31-liter twin-shaft continuous kneader reactor. The kinetic and torque models accurately predicted the observed performance of the continuous reactor. Due to errors in measuring the actual polymer temperature and the low temperature differences between the polymer and coolant, the overall heat transfer coefficient observed in the continuous reactor was much higher than that predicted by the batch trials. However, the overall heat transfer coefficients for the batch and continuous trials compare well when the basis for the temperature difference was the same. 

---