Electrospinning is commonly used for fabrication of polymer fibers. Melt electrospinning, instead of the commonly used solution electrospinning, offers many advantages in generating polymer fibers without using solvents. However, polymer melts have high viscosity which poses major limitations in producing low diameter fibers. Here, melt electrospinning is investigated at elevated temperatures in inert atmosphere to reduce fiber diameters while suppressing thermal degradation. Two types of spinneret configurations, syringe and wire, with two distinct outcomes are studied. In syringe‐based electrospinning, increasing the nozzle temperature from 300 to 360 °C in nitrogen reduced fiber diameter significantly from 33 ± 5 to 10 ± 4 µm. Electrospinning in nitrogen leads to formation of fibers even at a high nozzle temperature of 360 °C, while this temperature leads to thermal degradation when spinning in air. In contrast, increasing the temperature of wire electrospinning setup do not lead to a noticeable reduction in diameter. This is attributed to the viscosity‐dependent flow rate in this method. Increasing the temperature leads to increased flow rates, promoting the formation of thicker fibers, while the increased stretchability promotes the formation of thinner fibers. The results clearly demonstrate advantages of developing polymer microfibers in inert atmosphere to avoid thermal degradation with a temperature‐independent flow control.
Poly(lactic acid) (PLA) has a significant potential as a biodegradable polymer, but its high cost and slow biodegradability restrict its use in disposable products. This study establishes a novel route to accomplish both objectives by the addition of low‐cost soy fillers into PLA, which reduced material cost and increased the degradation rate of resulting soy‐PLA fibers. Due to partial thermal degradation of soy fillers at PLA melt temperature, they could be melt‐compounded into PLA up to 5 wt%. Fine continuous fibers (D ∼ 25‐50 μm) were successfully produced via melt spinning, and further melt‐consolidated into prototypical nonwovens. The tensile strength of soy‐PLA fibers containing soy reside and soy flour were 56 ± 9 and 44 ± 5 MPa, respectively. Although slightly lower than that of neat PLA fibers (74 ± 2 MPa), the fibers possessed adequate tenacity for use as nonwoven fabrics. Fiber modulus remained unaffected at about 2.5 GPa. The soy‐PLA fibers displayed a relatively rough exterior surface and provided a natural‐fiber feel. The overall degradation of soy‐PLA fibers was accelerated about 2‐fold in a basic medium due to the preferential dissolution of soy that led to increased surface area within the PLA matrix indicating their potential for use in biodegradable nonwovens.
more » « less- NSF-PAR ID:
- 10456510
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Polymer Engineering & Science
- Volume:
- 60
- Issue:
- 6
- ISSN:
- 0032-3888
- Page Range / eLocation ID:
- p. 1158-1168
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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