Molecular weight distribution modeling in low-density polyethylene polymerization; impact of scission mechanisms in the case of CSTR

From Molecular to Plant‐Scale Modeling of Polymerization Processes: A Digital High‐Pressure Low‐Density Polyethylene Production Paradigm

“…Based on the random segment connection algorithm, a number of research studies have been published on the prediction of the exact topological architecture of highly branched polymer chains. Most notably, Iedema and his co-workers [58,59] described a graph-based approach for efficient storage of the relevant polymer chain topological information while the chain length and branching distributions of the macromolecular segments were calculated via the implementation of a Galerkin on finite elements method. In a recent publication by the same group [60], the random segment connection algorithm was replaced by a backtracking algorithm that displayed limited applicability to real polymerization processes (i.e., with a comprehensive kinetic mechanism).…”

Mathematical modeling of the bivariate molecular weight—Long chain branching distribution of highly branched polymers.

“…In the past 20 years, several mathematical models dealing with the calculation of the MWD of branched polymers have been published (Tobita and Hatanaka, 1996;Thomas, 1998;Pladis and Kiparissides, 1998;Iedema et al, 2000;Kim et al, 2004). A variety of numerical methods have been employed to calculate the MWD of branched polymers, including the 'numerical fractionation' method (Teymour and Campbell, 1992), Monte-Carlo simulations (Tobita and Hatanaka, 1996) and discrete weighted Galerkin methods (Wulkow, 1995).…”

Prediction of the Bivariate Molecular Weight‐Long Chain Branching Distribution in High‐Pressure Low‐Density Polyethylene Autoclaves

“…The role of random scission in the development of the MWD for LDPE is not fully understood and requires special treatment. In general, random scission can be described by a two-step mechanism [see Equation (8) and (9)]. In the first step, a hydrogen atom is abstracted from the backbone of a 'dead' polymer chain by a 'live' polymer chain.…”

“…[1][2][3][4][5][6][7][8] A variety of numerical methods have been employed, including the 'numerical fractionation' method, [9,10] Monte-Carlo simulations, [11,12] global orthogonal collocation, [13,14] and discrete weighted Galerkin methods. [15,16] Butte et al [17] described a 2-D sectional-grid method for solving the bivariate PBEs.…”

“…[4,5] The detailed kinetic mechanism of random scission of branched polymer chains is a notoriously complex problem. In the past, several attempts have been made [8,[22][23][24][25][26] to describe the scission of LDPE polymer chains. The role of random scission in the development of the MWD for LDPE is not fully understood and requires special treatment.…”