Figure 1.
Our 600-nozzle pilot-scale electrospinning machine.
Figure 1.
Our 600-nozzle pilot-scale electrospinning machine.
Figure 2.
Schematic illustration of our electrometer setup.
Figure 2.
Schematic illustration of our electrometer setup.
Figure 3.
Overview of the experimental approach.
Figure 3.
Overview of the experimental approach.
Figure 4.
Rheograms representing a time sweep of PLA at different temperatures, showing a loss of complex viscosity at 250 °C.
Figure 4.
Rheograms representing a time sweep of PLA at different temperatures, showing a loss of complex viscosity at 250 °C.
Figure 5.
TGA thermogram of dyes during (a) the heating ramp to 230 °C and (b) the isothermal step at 230 °C for 60 min.
Figure 5.
TGA thermogram of dyes during (a) the heating ramp to 230 °C and (b) the isothermal step at 230 °C for 60 min.
Figure 6.
Antibacterial activity testing of (a) alizarin, (b) curcumin, and (c) quercetin against E. coli before and after thermal treatment of the dyes at 230 °C.
Figure 6.
Antibacterial activity testing of (a) alizarin, (b) curcumin, and (c) quercetin against E. coli before and after thermal treatment of the dyes at 230 °C.
Figure 7.
Antibacterial activity testing of (a) alizarin, (b) curcumin, and (c) quercetin against S. aureus before and after thermal treatment of the dyes at 230 °C.
Figure 7.
Antibacterial activity testing of (a) alizarin, (b) curcumin, and (c) quercetin against S. aureus before and after thermal treatment of the dyes at 230 °C.
Figure 8.
DSC thermogram representing dyes at different temperatures, showing an endothermic peak for curcumin.
Figure 8.
DSC thermogram representing dyes at different temperatures, showing an endothermic peak for curcumin.
Figure 9.
GPC elugram and the Mw, Mn, and PDI of pure PLA and its composites containing 5% (w/w) of alizarin (A5), curcumin (C5), or quercetin (Q5).
Figure 9.
GPC elugram and the Mw, Mn, and PDI of pure PLA and its composites containing 5% (w/w) of alizarin (A5), curcumin (C5), or quercetin (Q5).
Figure 10.
FTIR spectra of pure PLA and its composites containing 5% (w/w) of alizarin (A5), curcumin (C5), or quercetin (Q5).
Figure 10.
FTIR spectra of pure PLA and its composites containing 5% (w/w) of alizarin (A5), curcumin (C5), or quercetin (Q5).
Figure 11.
TGA thermogram of PLA and its composites containing 5% (w/w) of alizarin (A5), curcumin (C5), or quercetin (Q5) during (a) the heating ramp from 25 to 230 °C and (b) the isothermal step for 60 min at 230 °C.
Figure 11.
TGA thermogram of PLA and its composites containing 5% (w/w) of alizarin (A5), curcumin (C5), or quercetin (Q5) during (a) the heating ramp from 25 to 230 °C and (b) the isothermal step for 60 min at 230 °C.
Figure 12.
Isothermal rheogram of PLA and its composites containing 5% (w/w) of alizarin (A5), curcumin (C5), or quercetin (Q5).
Figure 12.
Isothermal rheogram of PLA and its composites containing 5% (w/w) of alizarin (A5), curcumin (C5), or quercetin (Q5).
Figure 13.
DSC thermograms of PLA and its composites containing 5% (w/w) of alizarin (A5), curcumin (C5), or quercetin (Q5) during (a) the heating cycle and (b) the cooling cycle.
Figure 13.
DSC thermograms of PLA and its composites containing 5% (w/w) of alizarin (A5), curcumin (C5), or quercetin (Q5) during (a) the heating cycle and (b) the cooling cycle.
Figure 14.
Rheogram of melt-electrospun fibers formed of PLA and its composites containing 1%, 3%, or 5% (w/w) of alizarin (A1, A3, A5), curcumin (C1, C3, C5), or quercetin (Q1, Q3, Q5).
Figure 14.
Rheogram of melt-electrospun fibers formed of PLA and its composites containing 1%, 3%, or 5% (w/w) of alizarin (A1, A3, A5), curcumin (C1, C3, C5), or quercetin (Q1, Q3, Q5).
Figure 15.
Complex viscosity of melt-electrospun fibers formed of PLA and its composites containing 1%, 3%, or 5% (w/w) of alizarin (A1, A3, A5), curcumin (C1, C3, C5), or quercetin (Q1, Q3, Q5) at an angular frequency of 10 rad/s.
Figure 15.
Complex viscosity of melt-electrospun fibers formed of PLA and its composites containing 1%, 3%, or 5% (w/w) of alizarin (A1, A3, A5), curcumin (C1, C3, C5), or quercetin (Q1, Q3, Q5) at an angular frequency of 10 rad/s.
Figure 16.
Electrical resistance of PLA and its composites containing 1%, 3%, or 5% (w/w) of alizarin (A1, A3, A5), curcumin (C1, C3, C5), or quercetin (Q1, Q3, Q5).
Figure 16.
Electrical resistance of PLA and its composites containing 1%, 3%, or 5% (w/w) of alizarin (A1, A3, A5), curcumin (C1, C3, C5), or quercetin (Q1, Q3, Q5).
Figure 17.
Mean diameter of fibers in webs prepared from pure PLA at different pump speeds of 2 rpm (P2), 5 rpm (P5), and 10 rpm (P10).
Figure 17.
Mean diameter of fibers in webs prepared from pure PLA at different pump speeds of 2 rpm (P2), 5 rpm (P5), and 10 rpm (P10).
Figure 18.
Mean diameters of fibers prepared from pure PLA and composites containing 1%, 3%, or 5% (w/w) of alizarin (A1, A3, A5), curcumin (C1, C3, C5), or quercetin (Q1, Q3, Q5) at pump speeds of (a) 2 rpm, (b) 5 rpm, and (c) 10 rpm.
Figure 18.
Mean diameters of fibers prepared from pure PLA and composites containing 1%, 3%, or 5% (w/w) of alizarin (A1, A3, A5), curcumin (C1, C3, C5), or quercetin (Q1, Q3, Q5) at pump speeds of (a) 2 rpm, (b) 5 rpm, and (c) 10 rpm.
Figure 19.
Visual appearance of melt-electrospun fiber webs prepared from (a) pure PLA and composites containing 5% (w/w) of (b) alizarin, (c) curcumin, and (d) quercetin.
Figure 19.
Visual appearance of melt-electrospun fiber webs prepared from (a) pure PLA and composites containing 5% (w/w) of (b) alizarin, (c) curcumin, and (d) quercetin.
Figure 20.
DSC thermograms of (a) PLA webs spun at different pump speeds (P2, P5, and P10 = 2, 5, and 10 rpm, respectively) and (b) PLA and PLA composite webs spun at a pump speed of 5 rpm (A5, C5, and Q5 = composites containing 5% (w/w) alizarin, curcumin, and quercetin, respectively).
Figure 20.
DSC thermograms of (a) PLA webs spun at different pump speeds (P2, P5, and P10 = 2, 5, and 10 rpm, respectively) and (b) PLA and PLA composite webs spun at a pump speed of 5 rpm (A5, C5, and Q5 = composites containing 5% (w/w) alizarin, curcumin, and quercetin, respectively).
Figure 21.
GPC elugram of melt-electrospun fiber webs formed of pure PLA or PLA composites containing 5% (w/w) of alizarin (A5), curcumin (C5), or quercetin (Q5).
Figure 21.
GPC elugram of melt-electrospun fiber webs formed of pure PLA or PLA composites containing 5% (w/w) of alizarin (A5), curcumin (C5), or quercetin (Q5).
Figure 22.
Antibacterial activity of melt-electrospun webs of pure PLA or PLA composites containing 5% (w/w) of alizarin (A5), curcumin (C5), or quercetin (Q5) against S. aureus at a 10−5 dilution.
Figure 22.
Antibacterial activity of melt-electrospun webs of pure PLA or PLA composites containing 5% (w/w) of alizarin (A5), curcumin (C5), or quercetin (Q5) against S. aureus at a 10−5 dilution.
Table 1.
Chemical structures and melting points of the dyes used in this study [
19,
27].
Table 1.
Chemical structures and melting points of the dyes used in this study [
19,
27].
Additive | Chemical Structure | Melting Point (°C) |
---|
Alizarin | | ~280 |
Curcumin | | ~175 |
Quercetin | | ~320 |
Table 2.
PLA/dye composites used for the spinning trials.
Table 2.
PLA/dye composites used for the spinning trials.
Composite Abbreviation | Colorant Name | Percentage (w/w) of Colorant |
---|
PLA | – | - |
A1 | Alizarin | 1 |
A3 | 3 |
A5 | 5 |
C1 | Curcumin | 1 |
C3 | 3 |
C5 | 5 |
Q1 | Quercetin | 1 |
Q3 | 3 |
Q5 | 5 |
Table 3.
Average molecular weights and PDI of PLA and its composites.
Table 3.
Average molecular weights and PDI of PLA and its composites.
Sample | Mn (g/mol) | Mw (g/mol) | PDI |
---|
Pure PLA | 55,000 ± 5000 | 105,000 ± 10,500 | 1.89 ± 0.3 |
Alizarin A5 | 54,400 ± 5340 | 105,000 ± 9800 | 1.92 ± 0.2 |
Curcumin C5 | 53,000 ± 5200 | 99,000 ± 9600 | 1.87 ± 0.4 |
Quercetin Q5 | 58,700 ± 5570 | 108,000 ± 10,000 | 1.84 ± 0.3 |
Table 4.
Thermal transition temperatures of PLA and its composites containing 5% (w/w) of alizarin (A5), curcumin (C5), or quercetin (Q5).
Table 4.
Thermal transition temperatures of PLA and its composites containing 5% (w/w) of alizarin (A5), curcumin (C5), or quercetin (Q5).
Material | Tg [°C] | Tcc [°C] | Trc [°C] | Tm [°C] | Tc [°C] |
---|
PLA | 59.70 | 95.90 | 160.90 | 176.10 | 98.70 |
A5 | 60.10 | 93.30 | 158.80 | 173.60 | 117.10 |
C5 | 60.70 | 96.10 | 158.80 | 174.00 | - |
Q5 | 62.50 | 95.80 | 157.00 | 174.10 | - |
Table 5.
Tg, Tcc, Tm, and Xc values of melt-electrospun fiber webs.
Table 5.
Tg, Tcc, Tm, and Xc values of melt-electrospun fiber webs.
Material | Tg [°C] | Tcc [°C] | Tm [°C] | Xc [%] |
---|
PLA P2 | 59.50 | 94.70 | 174.10 | 12.39 |
PLA P5 | 60.00 | 94.70 | 174.50 | 13.47 |
PLA P10 | 59.40 | 94.60 | 173.50 | 10.70 |
A5 P5 | 59.60 | 95.10 | 173.00 | 11.17 |
C5 P5 | 62.00 | 94.40 | 173.40 | 11.18 |
Q5 P5 | 60.00 | 95.80 | 173.90 | 12.27 |
Table 6.
The average molecular weight and PDI values of melt-electrospun fiber webs formed of pure PLA or PLA composites containing 5% (w/w) of alizarin (A5), curcumin (C5), or quercetin (Q5).
Table 6.
The average molecular weight and PDI values of melt-electrospun fiber webs formed of pure PLA or PLA composites containing 5% (w/w) of alizarin (A5), curcumin (C5), or quercetin (Q5).
Sample | Mn (g/mol) | Mw (g/mol) | PDI |
---|
PLA | 51,100 ± 3000 | 94,000 ± 9000 | 1.84 ± 0.2 |
A5 | 62,400 ± 5000 | 74,300 ± 6000 | 1.19 ± 0.3 |
C5 | 57,500 ± 5200 | 80,600 ± 7000 | 1.40 ± 0.4 |
Q5 | 56,900 ± 4000 | 91,800 ± 9000 | 1.61 ± 0.2 |