Preparation and properties of triphenyl octylphosphonium bromide‐modified vermiculite and its PBAT composite films

Abstract As living standards improve, there is a growing demand for fresher, healthier and more sustainable food options, with a concomitant challenge to develop new biodegradable packaging. This investigation centres around the synthesis of quaternary phosphonium salt (triphenyl octylphosphonium bromide P8) and use it to modify vermiculite (VMT). The structure of P8 was determined using both NMR and FTIR. The structural investigation and performance analysis of P8‐modified vermiculite (P8@VMT) were carried out by particle size, XRD, FTIR and microstructure. In addition, P8@VMT/PBAT composite films were prepared by solution method using PBAT as matrix material and P8@VMT as filler. The properties of P8@VMT/PBAT composite films were compared to those of pure PBAT films using TGA, DSC, SEM, and antibacterial tests. Results showed that the melting and crystallization temperatures of P8@VMT/PBAT composite films were higher than those of pure PBAT films. However, increasing the content of P8@VMT led to a decrease in thermal stability as well as melting enthalpy, crystallization enthalpy, and crystallinity. On the other hand, loss modulus, storage modulus, and complex viscosity significantly increased with the addition of P8@VMT. Compared to pure PBAT film, P8@VMT/PBAT‐20% composites exhibited a 19.6% reduction in tensile strength and a 94.7% decrease in elongation at break due to the presence of quaternary phosphonium salt (P8) used as a modifier for VMT during melt blending method preparation. Highlights Quaternary phosphonium salt P8 was successfully synthesized. PBAT/P8@VMT composite films with different P8@VMT were prepared. P8@VMT improves compatibility between VMT and PBAT. PBAT/P8@VMT composite films have antimicrobial effects. The PBAT/P8@VMT composite films are biodegradable.