Deuteration, cellulose samples

Fig. 11. Neutron-diffiaction pattern recorded on a normal (OH, left) and on a deuterated (OD) sample of cellulose ip. ...

Fig. 12. X-Ray and neutron fiber-diffraction patterns recorded from native cellulose (OH) and frilly deuterated (OD) cellulose samples. The difference in the scattering properties of hydrogen and deuterium (indicated by the red circles) allows the precise location of the electron density (shown in blue), which corresponds to the position of hydrogen atoms in the crystalline lattice. (See Color Plate 5.)...

Recent studies have shown that for the study of cellulose paracrystallinity, the combination of WAXS and deuteration methods is required (loelovich et al., 2010). Using these methods, it was found that the accessibility (A) of cellulose samples to deuteration exceeds the content of non-crystalline domains (H (Fig. 7.11). 

Figure 7.11 Relationship between accessibility to deuteration and amorphicity degree of cellulose samples.

Next, a correlation among Sa, Xam(X), the fraction of the accessible part (by heavy water) at equilibrium, as determined by the deuteration IR method, Xac(IR)> ar)d the relative amount of the higher field peaks of the C4 carbon peaks, Xh(NMR), were examined for samples having cellulose crystal form II, so as to clarify the factors contributing to Sa. In this case, Xi,(NMR) was estimated from Eq. (60) ... 

Deuteration has also been used as a gravimetric method for determining accessibility, the results for cotton being in exact agreement with those of Valentine. The linear relationship which exists between moisture sorption and the fraction of material found to be amorphous to infrared has been confirmed for thirteen different t5qies of cellulose, and it is suggested that a difference in the ratio of moisture regain to amorphous content between samples of cellulose I and cellulose II reflect differences in their sorption behavior and, hence, in the structure of their amorphous... 

The authors wish to thank Dr. H. L. Crespi for furnishing the sample of deuterated bacterial cellulose and for his advice concerning the growth of algae in heavy water, and Dr. U. P. Agarwal for the many helpful discussions he contributed to this work. Portions of this work were used by J. H. Wiley as partial fulfillment of the requirements for the Ph.D. degree at The Institute of Paper Chemistry. 

Crystallinity of each Avicel and Whatman CFll sample was determined by deuteration FTIR. Detailed information was described in the previous p p r (10). Figure. 1 shows that crystallinity decreases with the milling time. The crystallinity of Whatman CFll is 64.7% for the unmilled sample and decreases to 33.2% after 60 min of milling. The microcrystalline cellulose Avicel shows 58.8% crystallinity for the unmilled sample and 17.0% after 60 min milling. 

One year later, in 2003, Nishiyama, Sugiyama, Chanzy, and Langan retook their previous experiments for a cellulose. As before, they used s5mchrotron X-ray and neutron fiber diffraction to examine hydrogenated and deuterated samples. Experiments provided the following results [16] ... 

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