Synthesis and Processing of Melt Spun Materials from Esterified Lignin with Lactic Acid

Abstract

In this study, the carbon fiber manufacturing process is investigated, using high-density polyethylene (HDPE) and esterified lignin either with lactic acid (LA) or with poly(lactic acid) (PLA) as precursors. More specifically, lignin was modified using either LA or PLA in order to increase its chemical affinity with HDPE. The modified compounds were continuously melt spun to fibrous materials by blending with HDPE in order to fabricate a carbon fiber precursor. The obtained products were characterized with respect to their morphology, as well as their structure and chemical composition. Moreover, an assessment of both physical and structural transformations after modification of lignin with LA and PLA was performed in order to evaluate the spinning ability of the composite fibers, as well as the thermal processing to carbon fibers. This bottom–up approach seems to be able to provide a viable route considering large scale production in order to transform lignin in value-added product. Tensile tests revealed that the chemical lignin modification allowed an enhancement in its spinning ability due to its compatibility improvement with the commercial low-cost and thermoplastic HDPE polymer. Finally, stabilization and carbonization thermal processing was performed in order to obtain carbon fibers.

Synthesis and Characterization of a Core-Shell Copolymer with Different Glass Transition Temperatures

“…The FT-IR spectra of the produced polymers was analyzed via an attenuated total reflectance FT-IR instrument, the Cary 630 spectrometer (Agilent), with a resolution of 4 cm −1 and an operating wavelength range of 4000-400 cm −1 [34]. Thermal analysis of the produced polymers was conducted via a TGA/DSC instrument, the STA 449 F5 Jupiter.…”

“…The morphology and composition of the produced materials were estimated with an ultra-high resolution scanning electron microscope (UHR-SEM) using NOVA NANOSEM 230 (FEI Company) coupled with a Hitachi electron microscope TM3030 and an energy dispersive X-ray spectrophotometer (EDS) (QUANTAX 70) [33]. In addition, the morphology of the core-shell copolymers was also characterized by TEM (model FEI CM20), operated at an accelerating voltage of 200 kV [34][35][36].…”

“…Thermal analysis of the produced polymers was conducted via a TGA/DSC instrument, the STA 449 F5 Jupiter. The system consists of an SiC furnace with an operation temperature varying between 25 and 1550 • C. The gas used was nitrogen at a volumetric rate of 50 mL/min and at a heating rate of 20 • C/min [34]. The size distribution of the produced polymers was estimated via dynamic light scattering (DLS) measurements using a Zetasizer Nano ZS.…”

Introduction of a Methodology to Enhance the Stabilization Process of PAN Fibers by Modeling and Advanced Characterization

“…This can be better achieved by modifications of the stabilization process [4][5][6][7][8][9][10], since carbonization is a straightforward process that cannot be essentially altered and that investigation on novel CF precursors is time a consuming procedure. Polyacrylonitrile (PAN)-based CFs are more efficiently manufactured (due to their high carbon yield) and demonstrate a structure with less defects and voids, affording CF with high tensile strength in comparison to CFs derived from pitch, Rayon, or renewable precursors [1,[10][11][12][13][14][15]. Given that PAN-based CFs represent about 80-90% of the world production, there is a strong incentive for improving the process design, so that it might be further optimized [9,14,16].…”

Introduction of a Methodology to Enhance the Stabilization Process of PAN Fibers by Modeling and Advanced Characterization

“…This can be better achieved by modifications of the stabilization process [4][5][6][7][8][9][10], since carbonization is a straightforward process that cannot be essentially altered and that investigation on novel CF precursors is time a consuming procedure. PAN-based CFs are more efficiently manufactured (due to their high carbon yield) and demonstrate a structure with less defects and voids, affording CF with high tensile strength in comparison to CFs derived from pitch, Rayon, or renewable precursors [1,[10][11][12][13][14][15]. Given that PAN-based CFs represent about 80-90 % of the world production, there is a strong incentive for improving the process design, so that it might be further optimized [9,14,16].…”