Stearic acid-modified calcium sulfate whiskers as reinforcements for ultra-high molecular weight polyethylene

Industrial solid waste is an abundant but underexploited feedstock for advanced materials production. Herein, we develop a scalable strategy for the high-value utilization of flue gas desulfurization gypsum from Baotou Iron and Steel Group. We converted it into high-aspect-ratio (∼160) calcium sulfate whiskers (CSWs) via a hydrothermal route and modified their interfacial compatibility using stearic acid with an optimal concentration of 4 wt%, under which the modified CSWs exhibit an activation index of 0.618 and a water contact angle of 108°. When they are added to ultra-high-molecular-weight polyethylene (UHMWPE) as a reinforcement phase, the stiffness and toughness of the composite are enhanced, showing a maximum elongation at break of 331.16%, unchanged yield strength, improved flexural performance, and notched impact strength exceeding 70 kJ·m ^-2 . These results demonstrate the technical feasibility of transforming flue gas desulfurization gypsum into calcium sulfate whiskers for polymer reinforcement, offering an environmental and economical pathway for industrial solid waste valorization and advanced composite fabrication.