Preparation and properties of silane coupling agent modified vermiculite and its composite films

Vermiculite (VMT) was used as a filler and it was modified with silane coupling agent KH570 to produce OVMT. VMT/PBAT and OVMT/PBAT composite films were prepared using the solution method using polybutylene terephthalate (PBAT) as a matrix. The structure, thermal properties, crystalline properties, rheological properties, cross-sectional microstructure, and tensile properties and antibacterial properties of the pure PBAT film, VMT/PBAT, and OVMT/PBAT composite films were tested, including comparative analysis. The results showed that VMT was successfully modified with silane coupling agent to produce OVMT. Furthermore, the thermal stability of VMT/PBAT and OVMT/PBAT composite films decreased compared with pure PBAT film. As the content of VMT and OVMT increases, the energy storage modulus and loss modulus of VMT/PBAT and OVMT/PBAT composite films increase, while the loss factor, complex viscosity and crystallinity gradually decrease. Additionally, the tensile strength and elongation at break of VMT/PBAT and OVMT/PBAT composite films decrease. All three films had no effect on Staphylococcus aureus or Escherichia coli. The modification of VMT with the silane coupling agent KH570 improved the compatibility of OVMT with PBAT, resulting in improved mechanical properties of the OVMT/PBAT composite film compared with the VMT/PBAT composite film. The mechanical properties of the OVMT/PBAT-20% composite film increased by 35.9% in tensile strength and 10.8% in elongation at break compared with the VMT/PBAT-20% composite film.