Influence of the solvent type on the morphology and mechanical properties of electrospun PLLA yarns

Abstract

An electrospinning technique based on the use of two oppositely charged nozzles was applied to fabricate continuous twisted yarns of poly(L-lactide) (PLLA) nano/micro fibers. In this study, the effect of solvent on the electrospinning of PLLA fibrous yarns was investigated. For this purpose, yarns were electrospun using chloroform, dichloromethane or 2,2,2-trifluoroethanol as solvents at a PLLA concentration of 7 wt%. The analysis of the morphology, diameter, crystallinity and mechanical properties of electrospun yarns revealed that the vapor pressure of the solvent plays an important role. Whereas the fiber diameter decreased, the crystallinity of the fibers increased using a solvent with lower vapor pressure. In addition, mechanical properties (e.g., tensile strength and modulus) revealed that the yarns composed of fibers with smaller diameters showed higher tensile strength and modulus. In summary, fine-tuning solvent properties resulted in a modulation of fiber diameter, crystallinity, and thereby yarn mechanical properties, and are important factors to consider in the fabrication and application of electrospun yarns.

Morphological and mechanical properties of drawn poly(l‐lactide) electrospun twisted yarns

“…: where, Δ H m is the melting enthalpy and Δ H cc is the cold crystallization enthalpy. is the 100% melting enthalpy of PLLA polymer (93.7 J/g) .…”

“…In this work, to produce continuous twisted yarns, an electrospinning setup consisting of two oppositely charged nozzles was used. The fibers could be assembled into fibrous yarns using a device consisting of a take‐up roller and twister .…”

The influence of process parameters on the properties of electrospun PLLA yarns studied by the response surface methodology

“…One of these methods as developed more recently in our laboratories is the use of two oppositely charged needles. In this technique oppositely charged nanofibers create a triangle of fibers in the area between a neutral cylindrical surface and yarn convergence point, where nanofibers will be finally converged and twisted into yarn …”

“…In this study, the preparation and properties of twisted yarns from electrospun poly ( l ‐lactide) (PLLA) fibers by a continuous process is presented. PLLA is a thermoplastic polymer made from renewable resources and due to its biocompatibility, biodegradability, and mechanical properties has many applications especially as biocompatible/bioabsorbable medical devices . The response surface methodology (RSM) was used to systematically investigate process parameters that influence the fiber and yarn diameter and thereby the mechanical properties of the electrospun yarns.…”

Enhanced tensile strength and electrical conductivity of electrospun polyacrylonitrile Yarns via post‐treatment

“…For example, Ali et al in their study investigated the effect of twist level and the angle of twist on the tensile strength of the fiber yarns. Similarly, other research groups investigated the effect of electrospinning parameters such as solvent type and polymer concentration within the solution on the tensile strength and stiffness of the yarns . Wang et al in their study fabricated the yarns and applied post‐treatments to improve the strength of the fibers.…”