Poly (∊-caprolactone), (PCL) or simply polycaprolactone as it is usually referred to, is a synthetic biodegradable aliphatic polyester which has attracted considerable attention in recent years, notably in the biomedical areas of controlled-release drug delivery systems, absorbable surgical sutures, nerve guides, and three-dimensional (3-D) scaffolds, for use in tissue engineering. Various polymeric devices like microspheres, microcapsules, nanoparticles, pellets, implants, and films have been fabricated using this polymer. It can be transformed by spinning into filaments for subsequent fabrication of desirable textile structures. Spinning may be accomplished by various approaches. The fibers may be fabricated into various forms and can be used for implants and other surgical applications such as sutures. Although numerous studies have investigated different properties and applications of PCL, there is no comprehensive study investigating different fabrication methods of PCL fibers and their biomedical applications. The present article presents a review on the production of PCL fiber via various methods, along with correlations between structure and properties of the fibers. The applications of these fibers in biomedical domains are also discussed.

Wet spinning of polyacrylonitrile/carbon nanotubes (PAN/CNT) composite fibers was studied and the effect of spinning conditions on structure and properties of as-spun fibers influenced by the presence of CNTs investigated. Unlike PAN fibers, shear force had a larger effect on crystalline structure and physical and mechanical properties of PAN/CNT composite fibers compared to the elongational force inside a coagulation bath. Under shear force CNTs induced nucleation of new crystals, whereas under elongational force nucleation of new crystals were hindered but the already formed crystals grew bigger. To our knowledge, this key effect has not been reported elsewhere. At different shear rates, strength, Young’s modulus and strain at break of PAN/CNT as-spun fibers were improved up to 20% compared to PAN fibers. Application of jet stretch had less influence on physical and mechanical properties of PAN/CNT fibers compared to PAN fibers. However, the improvement of interphase between polymer chains and CNTs as a result of chain orientation may have contributed to enhancement of Young’s modulus of jet stretched composite fibers.

Co-polymers of lactide and glycolide, referred to as PLGA, have generated tremendous interest because of their excellent biocompatibility, biodegradability and mechanical strength. Various polymeric devices like microspheres, microcapsules, nanoparticles, pellets, implants, and films have been fabricated using these polymers. They can be transformed by spinning into filaments for subsequent fabrication of desirable textile structures. Spinning may be accomplished by various routes. The fibers may be fabricated into various forms and may be used for implants and other surgical applications such as sutures. They are also easy to formulate into various delivery systems for carrying a variety of drug classes. The present article presents a review on the production of PLGA fiber by various methods, along with correlations between structure and properties of the fibers. The applications of these fibers in biomedical domains are also discussed.

Acrylic fibers are the major precursor of carbon fibers. In this work, the synergistic effect of polymer concentration and jet stretching on porosity, morphology and mechanical properties of wet-spun poly(acrylonitrile) fibers were studied and then the role of void size was elucidated. The results showed that the effect of jet stretching on fiber porosity is negligible below a threshold polymer concentration. Increasing polymer concentration up to 20 vol. % reduced the total porosity significantly but increased the nanometric void population slightly. On the other hand increasing polymer concentration and jet stretching simultaneously, improved mechanical properties as a result of a remarkable reduction in porosity. In addition, stretching shifted nanovoids distribution strongly toward smaller sizes. This was attributed to the effect of stretching and increasing polymer concentration on reducing the diffusion coefficient. Young's modulus of fibers also increased with decreasing overall porosity. Finally, strength-diameter correlation showed a good agreement with the Griffith's theory.