New algorithm cuts time to switch plastics production between grades
Researchers have developed an optimization algorithm that dramatically speeds up the process of switching polypropylene production between different product grades. The breakthrough matters to manufacturers because grade switches currently cause costly downtime and waste—the new method could reduce transition time and help producers respond faster to shifting market demand.
Originaltitel: Trajectory optimization method for grade switching of polypropylene produced by Unipol process
<p>Polypropylene (PP) has excellent physical and chemical properties, and its products are widely used in various fields. In actual PP production processes, process parameters are usually determined by a single-objective optimization algorithm to have a unique optimal strategy set, but factories typically choose different switching strategies at different times. In order to meet the requirements of the actual grade switching process, the paper proposes a dynamic multi-objective grade switching model based on the polymerization reaction mechanism of the PP. The polymerization reaction mechanism of the PP is used to correlate the cumulative melt index (MI) and operating parameter. Then, the improved multi-objective slime mold algorithm incorporating the Lorentz distribution (IMOSMA-L) is proposed to efficiently optimize the grade switching process. Moreover, the IMOSMA-L introduces the Lorentz distribution function to improve the problem of the arctanh function converging too quickly. Meanwhile, the random search guided by the individual historical optimum of slime molds is introduced to prevent the optimization process from falling into local optimum. Finally, the IMOSMA-L algorithm is applied to optimize the transition processes from L5D98 to ZMK1870 and from L5D98 to ZM-FC801. Comparative experiments with several classical algorithms confirm that the IMOSMA-L achieves superior performance. Furthermore, when benchmarked against actual production data, the optimized switching process reduces PP waste by 48.77 tons and 78.3 tons under temperature fluctuation ranges of 5℃ and 2℃, respectively. © 2026 Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.</p>