A biodegradation study of poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/organoclay nanocomposites in various environmental conditions

Abstract

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)/organo-modified montmorillonite (OMMT) nanocomposite films were prepared by melt compounding and cast-film extrusion at various loading rates, i.e. 1, 3 and 5 wt. %. The effect of OMMT on the biodegradability of produced PHBV nanocomposite films was investigated under controlled conditions in aqueous medium (20 C for 28 days) by monitoring the biochemical oxygen demand (BOD), and under laboratory-scale composting conditions (58 C for 70 days) by monitoring the weight and surface loss. The microstructural and macromolecular changes were monitored during the biodegradation process by means of scanning transmission electron microscopy (STEM), differential scanning calorimetry (DSC) and size exclusion chromatography (SEC) analysis. The initial microstructure of the nanocomposites samples exhibited an intercalated structure with a good clay/matrix affinity. BOD evolution in aqueous conditions as well as surface and weight loss in composting conditions indicated that the biodegradation rate of PHBV nanocomposites was lower than neat PHBV, which supports a barrier effect of OMMT. This was confirmed by the surface erosion observed through SEM accompanied by a significant decrease of the average molecular weight in the bulk of the films. Our results demonstrated that the biodegradation of PHBV and nanocomposite films occurred by combined hydrolytic and enzymatic processes, at the surface as well as in the bulk of the material. DSC analysis also revealed no change in the degree of crystallinity, which suggests that the amorphous and crystalline phases were degraded at same rate.

The Effects of Gamma Irradiation on Molecular Weight, Morphology and Physical Properties of PHBV/ Cloisite 30B Bionanocomposites

“…The PHBV and bionanocomposite sheet samples, named Cast PHBV and C-PHBV/3C30B (prepared at a C30B content of 3 wt%) respectively were produced by masterbatch dilution with neat PHBV using a single-screw cast extruder. Our previous study [16] detailed the method of preparation of masterbatch and bionanocomposite sheet, and demonstrated the formation of intercalated bionanocomposites.…”

Polyhydroxybutyrate Composites with Random Mats of Sisal and Coconut Fibers

“…which W m is the weight fraction of PHB in composite, ΔH o is the melting enthalpy per unit mass of PHB and ΔH m is melting enthalpy per unit mass of the composite obtained from the integral of the peak melting temperature 56 .…”

Biodegradation of PHBV/GNS nanocomposites by Penicillium funiculosum

“…In relation to the carbonyl index, there was a small difference between amorphous and crystalline phases, suggesting that the enzymatic attack (microbial) occurs in both phases, reducing both the carbonyl of the amorphous phase and the crystalline phase …”

“…This process is mediated by microorganisms such as bacteria and fungi, which secrete enzymes that hydrolyze and oxidize these substrates, leading to breaking of chains in smaller products such as acids, aldehydes, and ketones. These products can be bioassimilated as carbon sources for their growth and thus promote the biodegradation of the polymeric material …”