# Application of Thermochemical Method to Determine the Crystallinity Degree of Cellulose Materials
## 4 Discussion
For example, the specific volume of amorphous cellulose is higher and the specific gravity is lower than that of crystalline cellulose. The sorption capacity of amorphous cellulose for vapors, molecules, and ions of various substances is relatively high, while that of crystalline cellulose is low and may even be zero. In addition, amorphous cellulose is highly reactive, while the theoretical reactivity of crystalline cellulose should be low. In practice, various cellulose samples are semi-crystalline polymers, so their properties (Z) depend on the degree of crystallinity (X), as follows:  
\[\rm{Z=X\cdot Zc+(1-X)Za=Za-X(Za-Zc)} \tag{7}\]  
where Zc and Za are the properties of completely crystalline (X = 1) and completely amorphous (X = 0) cellulose, respectively (Table 4). \begin{table}
\begin{tabular}{c c c c c} \hline
**Sample** & **Y** & **X** & **CrI** & **RD, \%** \\ \hline CC & 0.28 \(\pm\) 0.01 & 0.72 \(\pm\) 0.01 & 0.83 \(\pm\) 0.02 & 15 \\ MCC & 0.25 \(\pm\) 0.01 & 0.75 \(\pm\) 0.01 & 0.92 \(\pm\) 0.01 & 23 \\ CCM & 0.45 \(\pm\) 0.01 & 0.55 \(\pm\) 0.01 & 0.68 \(\pm\) 0.02 & 24 \\ KP & 0.35 \(\pm\) 0.01 & 0.65 \(\pm\) 0.01 & 0.78 \(\pm\) 0.02 & 20 \\ SP & 0.37 \(\pm\) 0.01 & 0.63 \(\pm\) 0.01 & 0.75 \(\pm\) 0.03 & 19 \\ SPM & 0.47 \(\pm\) 0.01 & 0.53 \(\pm\) 0.01 & 0.66 \(\pm\) 0.03 & 24 \\ VF & 0.62 \(\pm\) 0.01 & 0.38 \(\pm\) 0.01 & 0.54 \(\pm\) 0.02 & 42 \\ \hline \end{tabular}
\end{table} 
Table 3: Degree and index of crystallinity and degree of amorphicity for cellulose samples. Using Equation (7), it is possible to calculate various properties of cellulose materials, such as specific volume, specific gravity, amount of sorbed moisture from the vapor phase, amount of sorbed alkalis from aqueous solutions, accessibility for deuterium, the acidic hydrolysis, as well as amount of sorbed iodine and dyes from aqueous solutions, enzymatic digestibility, coefficient of thermal expansion, specific heat capacity, etc. [2; 3; 8]. To illustrate the possibility to predict some properties of cellulose materials, two samples, namely cotton cellulose (CC) and viscose rayon fibers (VF) having a high (X = 0.72) and low (X = 0.38) degree of crystallinity, respectively, were chosen. The properties of these samples were calculated (Calc) by Equation (7), after which they were compared with the experimentally obtained properties (Exp). As can be seen from Table 5, the calculations are in good agreement with the experimental data, which confirms the possibility of predicting the various characteristics of cellulose materials using such a parameter as real crystallinity degree. It can be noted that the thermochemical method for determining the crystallinity degree of cellulose samples is direct, simple, fast, precise, reliable, and reproducible. To measure the wetting enthalpy, any type of precise calorimeter produced by high-tech companies can be applied, such as adiabatic, isothermal, microcalorimeter, etc. Furthermore, it does not require the use of special models, complex software, and calculations. In this method, there are no special requirements for the shape and size of the samples. They do not need to be pressed or crushed. It is possible to use cellulose samples with different morphology and type of crystalline allomorph (CI, CII, CIII, or CIV) in the form of pieces, fibers, or powders. There are only two main conditions to prepare cellulose samples for testing, namely, they must be chemically pure and completely dry. For the removal of moisture from samples, a conventional vacuum drying at 378 K to constant weight can be used.