Filling of iron ore tailings into poly(vinyl chloride) based composites: Surface modification effect and performance enhancement

Filler agglomeration and poor compatibility between inorganic filler and organic matrix are key issues to affect the properties of PVC-based composites. Herein, surface treatment of iron ore tailings (IOT) was accomplished by commercially available silane and titanate coupling agents (SCA-K16M and TCA-KTTO), and the modified IOT, named S-IOT and T-IOT, were obtained correspondingly. Chemical modification of IOT by SCA-K16M and TCA-KTTO is successfully confirmed, and modification mechanism is revealed. IOT, T-IOT and S-IOT were subse-quently filled into PVC matrix to prepare composites. As T-IOT and S-IOT have better dispersibility and hy-drophobicity than IOT, and surface modification with coupling agent improves the inorganic-organic interface compatibility, the properties of S-IOT/PVC and T-IOT/PVC composites are better than those of IOT/PVC. In addition, TCA-KTTO has longer molecular chains and more contact sites on the surface of IOT than SCA-K16M, which makes T-IOT more evenly dispersed and closely adhered in PVC matrix. Hence, T-IOT/PVC composite exhibits the best performance. Its tensile strength, Young's modulus, and flexural strength are increased by 17%, 16%, and 13%, with a remarkable gain of 33% in notched impact strength compared to those of IOT/PVC. The co-extruded hollow floor fabricated by T-IOT/PVC composite meets Chinese standard GB/T 24508-2020.

Automated summary

Filler agglomeration and poor compatibility between inorganic filler and organic matrix are key issues affecting the properties of PVC-based composites. Surface treatment of iron ore tailings (IOT) with commercially available silane and titanate coupling agents improves the dispersibility and hydrophobicity of IOT, as well as enhances the inorganic-organic interface compatibility. As a result, the properties of the composites filled with modified IOT (S-IOT/PVC and T-IOT/PVC) are superior to those filled with unmodified IOT (IOT/PVC). Among the modified fillers, T-IOT shows the best performance, exhibiting significant improvements in tensile strength, Young's modulus, flexural strength, and notched impact strength.