Core shell fibers

Generally, it is important to know how to fabricate fibers with circular cross sections at will, and the aim of electrospinning for particular applications is in general to obtain just these particular types of fibers. On the other hand, other types of structure of fibers may be beneficial for specific functionality and applications. To date, by carefully controlling the preparing conditions, a variety of specific fiber structures originating from the complex self-assembly processes intrinsic in electrospinning have been fabricated, such as ribbon fiber, helix fiber, porous fiber, necklace-like fiber, core-shell fiber, and hollow fiber, as shown in Fig. 1.13. 

American Chemical Society [36].) Inset in (b) a close-up view showing the core-shell morphology of similar fibers. (Reprinted with permission from Chem. Eur. J., 1999, 5, 2740 [37].)... 

PF nanofibers are a second example of a top-down nanostructure. These fibers are conveniently prepared by electrospinning [143,144], a technique applied to PFs in work by Chen et al. [145] and Jenekhe et al. [146]. An example of PF8 nanofibers is shown in Fig. 34. In this study various different PFs were blended with PMMA and depending on the molar ratio and mother solution used, either uniform or core-shell structures were obtained. PF ag-... 

By contrast, the immiscible lignin/PP blend fibers form unique core/shell structure due to the difference... 

Jiang HL et al (2006) Modulation of protein release from biodegradable core-shell structured fibers prepared by coaxial electrospinning. J Biomed Mater Res B Appl Biomater 79B(1) 50-57... 

Wang C et al (2010) Biodegradable core/shell fibers by coaxial electrospinning processing, fiber characterization, and its application in sustained drug release. Macromolecules 43(15) 6389-6397... 

Finally, the basic Adhesive B formulation was toughened using the MEAc core-shell polymer and used as the matrix for an epoxy-graphite fiber composite. The mode II interlaminar fracture toughness, GIIc, was increased from 500 J/m2 to 890 J/m2 by the presence of the acrylic core-shell toughener. 

C-C. Kuo, C-T. Wang, and W-C. Chen, Poly(3-hexylthiophene)/Poly(methyl methacrylate) core-shell electrospun fibers for sensory applications. Macromolec. Symp., 279,41-47 (2009). 

Alexander, V.B. Alexander, L.Y. Constantine, M.M. Co-electrospinning of core-shell fibers using a single-nozzle techniqne. Langmuir 2007, 23 (5), 2311-2314. 

Figure 1. Experimental setup of the closed extrusion process for preparing GRIN polymer fibers. A and B, material supply tanks C and D, gear pumps E, a concentric die F, an enclosed zone G, (a) without core-shell separation die, (b) with core-shell separation die H, a hardening zone I, rolls.

Polymer fibers prepared by the extrusion process without a core-shell separation die design. 

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