Optimization of GCC Filler Use for Molded Pulp: A DOE Study of Pore Structure, Mechanical Properties, and Dewatering–Drying Efficiency

Abstract

Molded pulp packaging is rapidly growing as a sustainable packaging solution, but cost remains one of the biggest challenges. This study systematically investigates the potential use of mineral fillers as a cost-reduction strategy for molded pulp, using a design-of-experiments (DOE)-based approach. Laboratory-scale samples were produced with two ground calcium carbonate (GCC) fillers of different particle sizes at increasing dosages, and pore structure, mechanical properties, and dewatering/drying efficiency across stages of the molded-pulp process were assessed. With increasing filler dosage, mechanical properties decreased in three steps: slow initially, a steep mid-stage drop, then a slower final decline. The pore structure results correlated with this three-step change. The optimal filler-dosage range was determined from this three-step behavior and defined as the dosage corresponding to 80% of the maximum mechanical property reduction rate. GCC fillers improved the dewatering capability of the pulp suspension; however, this did not translate into improved dewatering efficiency at later stages. Future research is suggested to enable the successful application of mineral fillers in molded pulp products.