Analysis of Porous Electrospun Fibers from Poly(L-lactic acid)/Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) Blends

Solution blends of poly(L-lactic acid) (PLLA) and poly(3-hyroxybutyrate-co-3-hydroxyvalerate) (PHBV) in chloroform/DMF were electrospun at room temperature on a stationary collection plate. Polymer blend ratio, PHBV hydroxyvalerate content, solvent ratio, polymer concentration, and electrospinning process parameters were varied to determine optimal electrospinning conditions. The success of each formulation at producing nonwoven mats of continuous submicron diameter fibers was evaluated by optical and scanning electron microscopy. The diameter of the blend fibers was larger than electrospun fibers of either neat electrospun polymer, with a higher PLLA ratio favoring a porous surface morphology and higher PHBV ratios favoring beaded fiber morphology. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to analyze the thermal properties of the fibrous mats. The glass transition temperatures of the fibers from blends decreased as the PHBV weight ratio increased. The crystallinity of the PHBV fraction decreased as the ratio of the polymer in the blend decreased, whereas the crystallinity of PLLA was unaffected by the blend ratio. Dynamic mechanical analysis (DMA) indicated that the tensile strength of electrospun PHBV was improved by blending. Porous PLLA/PHBV electrospun fibers have potential for applications that need a high surface to volume ratio such as filtration, biomedical, energy storage devices, etc.