# Synthesis and Processing of Melt Spun Materials from Esterified Lignin with Lactic Acid
## 2 Materials and Methods
### Characterization  
The fibers composition and their morphology were determined with a Hitachi Electron Microscope TM303 coupled with an Ultra-High Resolution Scanning Electron Microscope (UHR-SEM) using NOVA NANOSEM 230 (FEI Company, Hillsboro, United States, 2009) and with an Energy Dispersive X-ray Spectrophotometer (EDS) (QUANTAX 70, BRUKER, Billerica, Massachusetts, United States, 2016). The Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy (FTIR) instrument Cary 630 spectrometer (Agilent, Santa Clara, California, United States, 2016) was used to analyze the FTIR spectra of the fibers. This instrument has a resolution of 4 cm\({}^{-1}\) and an operating wavelength range of 4000-400 cm\({}^{-1}\).  
The Thermogravimetric/Differential Scanning Calorimetry (TGA/DSC) instrument STA 449 F5 Jupiter (NETZSCH-Geratebau GmbH, Selb, Germany, 2017) was used for the thermal analysis of the fibers. The system consists of a SiC furnace with an operation temperature varying between 25 and 1550 \({}^{\circ}\)C. The maximum heating rate is 50 K/min. The gas used was nitrogen at a volumetric rate of 50 mL/min and at a heating rate of 20 \({}^{\circ}\)C/min.  
A Renishaw inVia spectrometer was used to perform micro-Raman measurements coupled with a green diode laser with emission at 532 nm (Renishaw plc, Gloucestershire, United Kingdom, 2013). The backscattering configuration was used. A beam spot size of 1 micrometer for a 1 mW beam at 1% intensity was used. The MATLAB 8.0 and Statistics Toolbox 8.1 (The MathWorks, Inc., Natick, Massachusetts, United States, 2012) was used for fitting the Raman signal to calculate the integrals of D and G peaks and quantify ID/IG ratio.  
The structure of the fibers was observed and collected by the instrument SkyScan 1272, a 3D X-ray scan system (BRUKER, Billerica, Massachusetts, United States, 2017). The system disposes an X-ray source which operates at 20-100 kV and 10 W (<5 \(\upmu\)m spot size @ 4W), an X-ray detector with a maximum resolution of 11 Mp (4032 \(\times\) 2688 pixels), and a CCD fiber of 14 bits, cooled and optically joined to a scintillator. During the observation, the specimens were fixed on a rotational stage, the distance between the rotation axis and the radiation source is set from 6 to 12 mm, and the pixel resolution is set to 2016 \(\times\) 1344 in order to obtain reliable images. Several stacked images were used for rendering, calculations, and image analysis for each sample.  
The tensile strength at the breaking point of the fiber was determined according to the scale of the dynamometer of the MPM-10 tensile test machine, based on the standards ISO 11566:1996 and ASTM D 3379-89.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Sample** & **150 \({}^{\circ}\)C, 1 h** & **220 \({}^{\circ}\)C, 3 h** & **300 \({}^{\circ}\)C, 10 min** & \begin{tabular}{c} **Proceeded to** \\ **Carbonization** \\ \end{tabular} & \
\begin{tabular}{c} **Successful** \\ **Carbonization** \\ \end{tabular} \\ \hline HDPE/SKL–LA & sustained (fiber & sustained & sustained & Yes & need for optimization \\ HDPE/SKL–PLA &
\begin{tabular}{c} sustained (fiber \\ shrinkage) \\ \end{tabular} & sustained & sustained & Yes & Yes \\ \hline \hline \end{tabular}
\end{table}
Table 2: Tabulated thermal treatment results.