Morphology and degradation behavior of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/layered double hydroxides composites.

In this study, poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/organo-modified Mg-Al layered double hydroxide (PHBV/m-LDH) nanocomposites and poly(3-hydroxybutyrate) (PHB)/m-LDH were synthesized and characterized as a new material for green material usages. The m-LDH was firstly prepared with oleate, magnesium nitrate hexahydrote and aluminum nitrate-9-hydrate by a novel one-step co-precipitation method to intercalate oleate into the interlayer of LDH. The m-LDH was characterized by X-ray diffraction (XRD) and a high interlayer spacing of 34.0 Å was obtained. To fabricate PHB/m-LDH and PHBV/m-LDH nanocomposites, the solution mixing process was investigated and shown to be an efficient method in this study. The structure, morphology and physical properties of PHB/m-LDH and PHBV/m-LDH nanocomposites were characterized using XRD, transmission electron microscopy, thermogravimetric analysis, and dynamic mechanical analysis. It has been shown that mechanical properties of PHB/m-LDH and PHBV/m-LDH nanocomposites have improved with the increasing m-LDH content up to tested 5 wt%. Finally, the biodegradability of PHB/m-LDH and PHBV/m-LDH nanocomposites is tested by using Caldimonas manganoxidans as a microbial catalyst. It has been shown that while the addition of m-LDH in each PHB-based nanocomposite enhances their mechanical properties, the addition of m-LDH up to 5% shows insignificant difference in terms of the biodegradability. Meanwhile, it is suggested that the PHB depolymerase of C. manganoxidans is dominated by the exo-type hydrolysis activity, where the degradation of PHB polymer starts from both ends of polymer chains. [ABSTRACT FROM AUTHOR]