Polyhydroxyalkanoates represent one of the biomaterials of the future due to their physicochemical properties, biodegradability, and biocompatibility. Poly (3-hydroxybuty-rate) (PHB) and Poly (3-hydroxybutyrate)-co-(3-hydroxyvalerate) (PHBV) with low percentage of valerate units is a promising bio-based and biodegradable thermoplastic but up to now with restricted industrial applications, due to its brittleness and poor processability, which is caused by a high tendency to recrystallization and a narrow melting intervall. Rubbery elastomers such as soft low-Tg-PHAs with longer side chains (medium chain length PHAs, mcl-PHAs) and other natural elastomers like natural rubber have been used as impact modifyers. To improve rubber dispersion and compatibility between the rubber phase and PHB/PHBV and to avoid recrystallization crosslinking/radical grafting was carried out. Besides rheological, crystallization, thermal, mechanical properties and especially the biodegradability of these blends was investigated because it is well known, that the length of sidechain, hydrophilicity and crystallinity have strong influence on biodegradability. In consequence, different extracellular PHB(V)-degrading depolymerases were selected, expressed, and characterized. The purified enzymes were estimated to have an apparent molecular mass between 22.0 and 50.0 kDa. In order to investigate the influence of the elastomeric blend compound and crossliking on biodegradability a pH dependent assay was established to monitor the degradation. Fluorescein was used to visualize the pH change. Each of the heterologous depolymerases were able to degrade crosslinked PHB/PHBV/elastomer blends. The depolymerase from P. lemoignei (P52090) showed the highest activities.

Studies on mechanical properties of crosslinked bio-polyester/elastomer – blends and their biodegradability

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.