Electrospinning of PCL-Based Blends: Processing Optimization for Their Scalable Production

Abstract

In this work poly(ε-caprolactone) (PCL) based electrospun mats were prepared by blending PCL with microcrystalline cellulose (MCC) and poly(3-hydroxybutyrate) (PHB). The electrospinning processing parameters were firstly optimized with the aim to obtain scalable PCL-based electrospun mats to be used in the industrial sector. Neat PCL as well as PCL-MCC and PCL-PHB based mats in different proportions (99:1; 95:5; 90:10) were prepared. A complete morphological, thermal and mechanical characterization of the developed materials was carried out. Scanning electron microscopy (SEM) observations showed that the addition of PHB to the PCL matrix considerably reduced the formation of beads. Both the addition of MCC and PHB reduced the thermal stability of PCL, but obtained materials with enough thermal stability for the intended use. The electrospun PCL fibers show greatly reduced flexibility with respect to the PCL bulk material, however when PCL is blended with PHB their stretchability is increased, changing their elongation at break from 35% to 70% when 10 wt% of PHB is blended with PCL. However, the mechanical response of the different blends increases with respect to the neat electrospun PCL, offering the possibility to modulate their properties according to the required industrial applications.

Keywords: blends; electrospinning; microcrystalline cellulose; poly(3-hydroxybutyrate); poly(ε-caprolactone); stretchability.

Figure 1

Number of publications on electrospun poly(ε-caprolactone) (PCL) fibers in the last 20 years (Scopus source).

Scheme 1

Schematic diagram of electrospinning in coaxial configuration.

Figure 2

Scanning electron microscopy (SEM) images of electrospun PCL fibers and their average diameters corresponding to different runs of Table 2: (a) Run II, (b) Run VIII, (c) Run XIII, (d) Run XIV, (e) Run XV, (g) Run XVIII and (h) Run XIX. The image (f) corresponds to Run XV at a higher magnification of 10,000×.

Figure 3

SEM images of (a) electrospun PCL-MCC mats and (b) PCL-PHB mats. Note: MCC = microcrystalline cellulose; PHB = poly(3-hydroxybutyrate).

Figure 4

Thermogravimetric analysis (TGA) of electrospun PCL-MCC and PCL-PHB mats: (a) TGA curve of PCL-MCC, (b) DTG curve of PCL-MCC, (c) TGA curve of PCL-PHB and (d) DTG curve of PCL-PHB.

Figure 5

DSC curves of the first heating scan of electrospun (a) PCL-MCC and (b) PCL-PHB mats.

Figure 6

X-ray diffraction (XRD) curves of electrospun (a) PCL-MCC and (b) PCL-PHB mats.

Figure 7

Stress–strain curves for electrospun neat PCL, PCL-MCC and PCL-PHB blends.

Figure 8

Variation of elastic modulus, tensile strength, and elongation at break for (a) PCL-MCC and (b) PCL-PHB blends.