Ft ir 8400 spectrophotometer

Nuclear Magnetic Resonance (NMR) charts were recorded by BRUKER 500 MHz Avance III. Chemical shifts are reported in ppm related to tetramethylsilane (TMS), internal standard. Deuterated chloroform (CDCl₃) was used as a solvent in sample preparation. ¹H-NMR data are reported as following: chemical shift (ppm), multiplicity, coupling constant (Hz), number of protons, and their corresponding proton(s). For initial identification of compounds, infrared (IR) spectra were recorded using Shimadzu 8400 FT-IR spectrophotometer (Japan). All tested compounds were triturated with potassium bromide (KBr) and compressed into thin film discs (ACros, Belgium). The melting point (m.p) was measured using Gallenkamp melting point apparatus (Gallenkamp, UK). Thin layer chromatography (TLC) was performed on 20 × 20 cm aluminum plates precoated fluorescent silica gel GF254 (ALBET, Germany). The TLC was visualized under UV lamp, Spectroline® cabinet, Model CX-20 (USA), at 254 and/or 360 nm. For the efficient and gentle removal of solvents from the samples, Rotavapor model R-114 (Buchi, Switzerland) was used.

For FTIR analysis, The KBr pressed disc technique (2–4 mg of sample and 200 mg of KBr) was used. Data acquired in Shimadzu 8400 FT-IR spectrophotometer. Absorbance spectra were obtained from 4000 to 400 cm-1 with a 4 cm-1 resolution, Background spectra were also collected and subtracted. The ¹H spectra were taken on a Bruker DPX200 (500 MHz for 13 C and 200 MHz for 1 H) in D₂O solvent using tetramethylsilane (TMS) as an internal standard. Both cases 5 mg/mL concentrated solutions were prepared. All signals were referenced to TMS within ± 0.1 ppm. The thermo oxidative stability of pure lignin and lig-g-POZ with different weight (%) lignin content copolymer were carried out using a TGA Q50 thermal analyzer of TA Instruments, USA. All the experiments were performed by heating the sample at a rate of 10 °C/min, in nitrogen atmosphere, from room temperature to 600 °C. DSC studies of the pure lignin and lig-g-POZ copolymer with different weight (%) lignin content were performed using a DSC Q100, of TA instruments make, USA. Approximately 10 mg of the samples was placed in an aluminum crimple and sealed with the help of a hand press prior to placing it on the sample platform of the instrument. The scanning was carried out in the temperature range of 30 °C to 200 °C at a heating rate of 10 °C/min in a stream of continuous supply of dry nitrogen.

The membranes’ functional groups were determined by an FT-IR-8400 spectrophotometer (Shimadzu, Kyoto, Japan) using a diamond tip as an accessory in a wavenumber range between 500–4000 cm⁻¹.