PRODUCTION AND CHARACTERIZATION OF PHB, PHBV ELECTROSPUN FIBERS AND THEIR BLENDS

Polhydroxbutyrates (PHBs) are well-known bio-based and biodegradable bacterial polyesters. In this study, the effects of polymer type, solution concentration and feeding rate on the electrospinnability of Poly(3-hydroxbutyrate) (PHB) and Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) PHBV nanofibers were investigated. First, PHB, PHBV and PHB/PHBV solutions with different polymer concentrations ranging between 5-11% wt. were prepared and characterized in terms of viscosity. Afterwards, electrospinning was performed and ultrafine fibers were produced. The surface morphology and the fiber diameters of the samples were investigated by scanning electron microscopy (SEM) analyses. Pore sizes of the samples were also calculated. In order to understand the wettability of the samples, contact angle measurements were conducted. The thermal properties and the crystallinity of the samples were investigated differential scanning calorimetry (DSC) analyses. The solution viscosities increased dramatically above %9 wt. of polymer concentration. SEM images revealed that decreasing feeding rate and increasing solution concentration resulted in fewer bead formation. On the other hand, fibers with diameters from 1.2 to 5.4 μm were produced with the increasing solution concentration and increasing voltage. All samples showed contact angle values above 90° indicating that they are hydrophobic. The PHB/PHBV blend surface showed the highest contact angle. DSC analyses showed that PHBV surface had significantly lower crystallization degree than PHB surface produced at the same concentration. It can be concluded that PHB fibers can be successfully produced by electrospinning.