New cellulose crystallinity estimation method that differentiates between organized and crystalline phases

A new method is proposed for estimation of cellulose crystallinity (CrI) based on 93 cm(-1) Raman band in spectra of cellulose I materials. In this method (93-Raman), CrI was determined based on regression that was developed using the ratios of peak-heights of the 93 and 1096 cm(-1) Raman bands (I-93/I-1096). For calibration purposes, a set of eight samples, all derived from cotton microcrystalline cellulose Whatman CC31 were selected. When the peak intensity ratios (I-93/I-1096) were plotted against the calculated CrIs of the calibration set samples, the plot showed an excellent linear correlation (R-2 = 0.9888). The 93-Raman method was used to estimate crystallinities of a number of cellulose materials including poplar wood samples that were hydrothermally treated at various temperatures. The wood 93-Raman CrI data showed that the method is able to differentiate between organized and crystalline phases of cellulose, a capability lacking in many other CrI estimation methods.