Impact of mesoporous glass microbeads prepared from coal gasification fine slag on the performance of polypropylene composites

In this research, mesoporous glass microbeads are prepared by the in-situ acid soluble reaction of the hydrochloric acid using coal gasification fine slag. The metal oxides are dissolved in the microbeads, generating mesoporous channels, and mesoporous spherical silica is successfully synthesized after calcination to remove residual carbon. Spherical glass microbeads are subsequently incorporated into the polypropylene matrix to investigate the influence of silica pore structure on polypropylene composite properties. Experimental results demonstrate that the addition of mesoporous silica enhances flexural strength and thermal stability while simultaneously reducing elongation at break and impact strength of the polypropylene. The mechanical properties of the composites exhibit a non-monotonic relationship with the dosage of hydrochloric acid, initially improving and then deteriorating with the increasing acid consumption. Insufficient acid results in inadequate pore formation, whereas excessive acid causes structural collapse through active silicon-HCl reactions. Optimal composite performance is achieved at an acid-ash ratio of 1.0, establishing the most favorable binding configuration between filler and matrix. The comparative analysis of mechanical properties, thermodynamic behavior, and interfacial bonding confirm that the synthesized mesoporous silica from coal gasification fine slag can effectively substitute 1250-mesh heavy calcium powder to application in polypropylene.