Smart orbit atr sampling accessory

Fourier-transform infrared spectroscopy (FT-IR) absorbance spectra were recorded within the 4000–400 cm⁻¹ range (64 scans, absorption mode). The experiment was performed with the use of a Thermo Scientific Nicolet 6700 FT-IR spectrometer equipped with diamond Smart Orbit ATR sampling accessory (Waltham, MA, USA). Based on the obtained results, carbonyl index (CI) was calculated according to Equation (1).
$$CI=\frac{absorbanc{e}_{C=O \left(~1720 {\mathrm{cm}}^{-1}\right)}}{absorbanc{e}_{C-H \left(~2900 {\mathrm{cm}}^{-1}\right)}}$$

Cellulose fibers were dried for 24 h at 100 °C (Binder^® oven; crystallizer 70 mm × 40 mm) before being analyzed. Fourier transform infrared spectroscopy (FT-IR) absorbance spectra were investigated within the 4000–400 cm⁻¹ range (64 scans, absorption mode). The experiment was performed with the use of a Thermo Scientific Nicolet 6700 FT-IR spectrometer (Thermo Fisher Scientific, Waltham, MA, USA) equipped with diamond Smart Orbit ATR sampling accessory.

To assess the structural changes that appeared due to the aging, the Fourier-transform infrared spectroscopy (FTIR) method was performed for all samples before and after weathering. The FTIR absorbance spectra were obtained by using a Nicolet 6700 FTIR spectrophotometer (Thermo Scientific) equipped with Smart Orbit ATR sampling accessory and the measurement range was between 4000 and 400 cm⁻¹ with 64 scans at 4 cm⁻¹ resolution. Furthermore, this analysis enabled the monitoring of material oxidation by observing changes that take place in the carbonyl (C=O) band. Therefore, based on the FTIR spectrum, a carbonyl index (CI) value was calculated for each sample before and after weather-aging with Equation (4) [54 (link)]: $\mathrm{Carbonyl}\mathrm{Index}=\frac{{\mathrm{I}}_{\mathrm{C}=\mathrm{O}}}{{\mathrm{I}}_{\mathrm{C}–\mathrm{H}}}$
where I_(C=O) is the peak intensity that corresponds to the C=O groups (~1740 cm⁻¹), and I_(C–H) is the peak intensity that represents the -CH groups (~1920 cm⁻¹).