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In the present paper, a dynamic optimization problem regarding grade transitions in bulk poly(propylene) polymerization processes is formulated and solved for the first time. Initially, a detailed dynamic process model is presented and implemented, comprising mass and energy balances, some of the polymer properties (such as the melting flow index and the xylene solubles) and regulatory control loops. Additionally, the effects of cocatalyst and electron donor on the propagation rate constant are taken into account. Then, the dynamic optimization problem is formulated and an evolutionary algorithm is used to solve the resulting nonlinear programming problem. It is shown that there is significant coupling among the manipulated variables and the controlled performance and polymer property variables, which adds complexity to the grade transition problem and demands the simultaneous manipulation of multiple variables during transitions. Despite the inherent open‐loop unstable nature of the analyzed process, it is shown that smooth grade transition trajectories can be accomplished through proper adjustment of the objective function weights. Finally, it is shown that the obtained optimum trajectories can significantly diminish the transition time, which can be of paramount importance for the plant economics. [ABSTRACT FROM AUTHOR]

Summary: This paper shows the characterization carried out in polypropylene nanocomposites made up with different proportions of modified nanoclays (1% 2.5% and 5%). Modified nanoclay (montmorillonite) has been added to improve the mechanical properties of the original matrix and increase its heat resistance. The objective of this work is to characterize multiscale nanocomposites, from nano-scale to macroestrucutural scale using thermography, nanoindentaton and mechanical testing. [ABSTRACT FROM AUTHOR]