Selected Simple Natural Antimicrobial Terpenoids as Additives to Control Biodegradation of Polyhydroxy Butyrate

In this experimental research, different types of essential oils (EOs) were blended with polyhydroxybutyrate (PHB) to study the influence of these additives on PHB degradation. The blends were developed by incorporating three terpenoids at two concentrations (1 and 3%). The mineralization rate obtained from CO2 released from each sample was the factor that defined biodegradation. Furthermore, scanning electron microscope (SEM), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA) were used in this research. The biodegradation percentages of PHB blended with 3% of eucalyptol, limonene, and thymol after 226 days were reached 66.4%, 73.3%, and 76.9%, respectively, while the rate for pure PHB was 100% after 198 days, and SEM images proved these results. Mechanical analysis of the samples showed that eucalyptol had the highest resistance level, even before the burial test. The other additives showed excellent mechanical properties although they had less mechanical strength than pure PHB after extrusion. The samples' mechanical properties improved due to their crystallinity and decreased glass transition temperature (Tg). DSC results showed that blending terpenoids caused a reduction in Tg, which is evident in the DMA results, and a negligible reduction in melting point (Tm).

Automated summary

This experimental research investigated the effects of different types of essential oils on the degradation of polyhydroxybutyrate (PHB). It was found that adding certain essential oils can reduce the biodegradation rate of PHB. SEM, DSC, and DMA were used to characterize the samples. The results showed that PHB blended with 3% eucalyptol, limonene, and thymol had biodegradation percentages of 66.4%, 73.3%, and 76.9%, respectively, after 226 days. Additionally, these additives exhibited good mechanical properties, with eucalyptol showing the highest resistance level.