Influence of the Pre-Intercalated Alkyl Chain Length of Nano-Montmorillonite on the Dielectric Relaxation and Degradation Behavior of PBAT Composites

The successful pre-intercalation of ammonium salts with alkyl chain lengths ranging from C10 to C22 into nano-montmorillonite (MMT) significantly increases the interlayer spacing. After melt blending, the distribution of organically modified MMT in the PBAT matrix improves with the increase in the length of the pre-intercalated alkyl chains. Broad dielectric relaxation spectroscopy (BDRS) reveals that the length of the pre-intercalated chains has minimal effect on the glass transition temperature ( T g ). Furthermore, the α-relaxation transitions to lower temperatures with an increase in the length of the pre-intercalated chains, demonstrating the plasticization of rigid amorphous regions driven by alkyl chain mobility. Hydrolysis degradation analysis reveals that PBAT/MMT with C22 exhibits the slowest degradation rate, as dispersion effects effectively suppress water diffusion through the composite films by prolonging the effective diffusion pathways. These findings highlight the critical role of pre-intercalated chain length in modulating the molecular dynamics and degradability of PBAT/MMT composite films.