Physiochemical performance of electrospun PLA-lignin and PVA-lignin

Abstract

Polylactic acid (PLA) and polyvinyl alcohol (PVA) are promising biocompatible and biodegradable materials for biomedical uses, yet they have limitations. Similarly, lignin is a precursor for carbon fiber but requires plasticizers to be spun into fibers. This hampers their use in areas like carbon fiber production and tissue engineering, thus the reason for this study. Lignin was extracted from the plantain stem, and a lignin blend with PLA and PVA was made and electrospun into fibers. Thereafter, the physiochemical properties of the composite fibers were analyzed. The XRD spectra revealed increased crystallinity in PLA/Lignin fiber. When 0.75 wt.% of lignin was added to PVA, a new peak and peak shift were formed in the composite fiber, indicating strong interaction. The crystallinity of PVA/lignin decreased from 71.5 to 60.1% when 0.25 wt. % of lignin was added. DSC showed miscibility of polymers and improved melting temperatures from 155 to 228 °C, for PLA/lignin (0.5wt.%) fiber, but a reduction in melting temperatures of PVA, with higher lignin content (149–143 °C). FTIR showed notable functional groups, typical of PLA, PVA, and lignin, such as the OH group between 3800 and 3459 cm⁻¹. The minor peak shift in PLA/lignin showed that the level of molecular interaction is less than that of PVA/lignin. PLA/lignin displayed better fiber morphology compared to PVA/lignin, where fibers became sheet-like with higher lignin content. The addition of lignin improved the tensile strength of PVA (0.7 to 2.7 MPa). Conversely, PLA/lignin’s tensile strength decreased, due to reduced load transfer efficiency. Overall, PVA/lignin and PLA/lignin composites exhibit potential as reinforcement materials for biopolymers and carbon fiber precursors, with PVA showing more promise for carbon fiber production due to robust polymer-lignin interaction.