Influence of Electrospinning Parameters on Fiber Diameter and Mechanical Properties of Poly(3-Hydroxybutyrate) (PHB) and Polyanilines (PANI) Blends

Abstract

Random and oriented fibers of poly (3-hydroxybutyrate) (PHB) and their blends were manufactured using electrospinning using a co-solvent. The kind and the concentration of the co-solvent affected the diameter of electrospun fibers. The morphology, thermal analysis, and crystalline structure of electrospun fibers was studied using polarized optical microscop (POM), Differential scanning colametry (DSC), Scanning Electron Microscopy (SEM), Wide angle X-ray diffraction (WAXD), and FT-IR analysis. The diameter of the electrospun fibers decreases with increasing collector speed for the blends compared to pure PHB, which are about 6 µm in diameter. The fibers obtained from blends reduce to 2 µm. The aligned electrospun fiber mats obtained from pure PHB showed no signs of necking at different take-up speeds, but the blends show multiple necking. It was found by FT-IR that the peak intensity at 1379 cm^-1 was lower by take up speed than in casting films; this peak is sensitive to crystallinity of PHB. The addition of polyanilines (PANIs) to (PHB) with a plasticizer decreases the diameter of the electrospun fiber.

Keywords: Polyanilines (PANI); conductive biopolymers; electrospun fiber; mechanical properties; poly(3-hydroxybutyrate) (PHB).

Figure 1

The samples of pure PHB and blend 1 were collected on the aluminum foil with the following die diameter, applied voltages, CF/DCM ratios, flow rate, and the distance between needle and target: 20 wt %, 1.3 mm, 20 kV, 75:25, 0.185 µm·h⁻¹, and 20 cm, respectively; (a,a') pure PHB at a fixed target (random) and rotating drum with a speed of 1100 rpm with polymer concentrations of 20%; (b,b') blend 1 at a fixed target (random) and at a rotating drum with a speed 1100 rpm with polymer concentrations of 25%.

Figure 2

The samples of pure PHB at different scales were collected on the aluminum foil with the following polymer concentrations, die diameter, applied voltages, CF/DMF ratios, flow rate, and distance between the needle and target: 20 wt %, 1.3 mm, 20 kV, 90:10, 0.185 µm·h⁻¹, and 20 cm, respectively. (a,c) at a fixed target (random) with different scales, and (b,d) at a rotating drum with a speed of 1100 rpm.

Figure 3

The samples of blend 1 at different scales and speeds were collected on the aluminum foil with the following polymer concentrations, die diameter, applied voltages, CF/DMF ratios, flow rate, and distance between the needle and target: 25 wt %, 1.3 mm, 20 kV, 90:10, 0.185 µm·h⁻¹ and 20 cm, (a,c) at fixed target (random); (b,d) at a rotating drum with a speed of 1100 rpm, respectively.

Figure 4

The samples of blend 2 were collected on the aluminum foil with the following polymer concentrations, die diameter, applied voltages, CF/DMF ratios, flow rate, and distance between the needle and target: 25 wt %, 1.3 mm, 20 kV, 90:10, 0.185 µm·h⁻¹, and 20 cm. (a) at a fixed target (random); (b) at a rotating drum with a speed of 380 rpm; (c) at a rotating drum with a speed of 490 rpm; (d) at a rotating drum with a speed of 610 rpm; (e) at a rotating drum with a speed of 740 rpm, and (f) at a rotating drum with speed 850 rpm.

Figure 5

Stress-strain curves of nanofibers: (a) pure PHB with a speed of 610 rpm; (b) blend 2 with a speed of 610 rpm; (c) blend 2 (random); and (d) blend 1 (random).

Figure 6

SEM micrographs of fractured surfaces of multiple neck formations in electrospun fibers of blend 2 (a, b, and c) and blend 1 (d) after cold drawing, at different magnifications.

Figure 7

DSC curves for pure PHB and its blends (a) first heating; (b) cooling; (c) second heating; and (d) second heating to determine the glass transition temperature region.

Figure 8

WAXD of electrospun fibers of (a) pure PHB with different take-up speeds (v), (b) blend 1 with different take-up speeds, and (c) pure PHB, blends 1, 2, and blend 2 with different take-up speed (v).

Figure 9

FT-IR spectrum of electrospun PHB and their blends in the infrared spectrum regions at different take-up speeds (a) from 400 to 1600 cm⁻¹ of PHB and (a') from 1600 to 4000 cm⁻¹ of PHB; (b) from 400 to 1600 cm⁻¹ of blend 10; and (b') from 1600 to 4000 cm⁻¹ of blend 10; (c) from 400 to 1600 cm⁻¹ of blends 10, 14, 16, 17, and (c') from 1600 to 4000 cm⁻¹ of pure PHB and blends 1 and 2, at constant take-up speeds of 490 rpm, but blends 3 and 4 as a casting film.