Mercerized ramie

Acetylation rates have also been studied by Centola37 who treated natural and mercerized ramie fibers for varying times with acetic anhydride and sodium acetate and examined the reaction products chemically and by X-ray diffraction. The reagent was considered to penetrate into the interior of fibers. A heterogeneous micellar reaction was believed to occur that converted a semi-permeable elastic membrane around the micelles into the triacetate. The rate of acetylation of mercerized ramie was observed to be faster than that of unmercerized fiber. Centola concluded that about 40 % of the cellulose in native ramie is amorphous and acetylates rapidly. 

Cellulose II. Fortlsan, ordinary viscose rayon, mercerized ramie, mercerized bacterial cellulose, and saponified triacetate film were used. A film having uniaxial orientation was prepared from saponified triacetate film by stretching and drying under tension. 

Cellulose polymorphy was studied by comparing the spectra of Valonia, ramie, and mercerized ramie. It appears that the conformation of the cellulose backbone is the same in Valonia and ramie celluloses, but that the hydrogen bonding patterns are different. Mercerized cellulose and native celluloses differ in both their backbone conformations and hydrogen bonding patterns. 

Two classes of experiments were conducted. In both sets of experiments, fibers in which the cellulose chains are oriented parallel to the fiber axis were used. In the first class of experiments, the plane of polarization of the incident light was changed relative to the axis of the fibers by rotating the fibers around the optical axis of the microscope (see Figure 2a). The dependence of the band intensities on the polarization of the incident light was studied to determine the directional character of the vibrational motions. This information was used to advance the assignment of the Raman spectrum of cellulose. Spectra from Valonia, ramie, and mercerized ramie fibers, which have different allomorphic compositions, were compared to study the structural differences between the allo-morphs. 

The cellulose I spectra were also compared with spectra of ceTTulose II recorded from a mercerized ramie fiber. Figures 7 and 8 show the Raman spectra of these three celluloses. Spectra were recorded with the electric vector of the incident light parallel and perpendicular to the chain axis. These spectra can be divided into two regions. The region below 1600 cm (Figure 7) is most sensitive to the conformation of the cellulose backbone (especially below 700 cm" ). 

Figure 7. Comparison of the Raman spectra from Valonia, ramie, and mercerized ramie (low frequency region). Spectra were recorded with the electric vector at both 0 and 90°.

In the 0-H stretching region (3200-3600 cm ), however, significant differences are observed between all three celluloses. These differences are most prominent in the spectra recorded with the electric vector parallel to the fiber axis (Figure 8a-c). The frequency as well as the broadness of the peaks varies in this region. The spectra of Valonia cellulose have a peak at 3231 cm that is not observed in the ramie spectra. The spectra of native ramie on the other hand, have a peak at 3429 cm that is not observed in Valonia. The spectrum of mercerized ramie recorded with the elec-... 

As can be seen in table 2, a number of unit cells have been proposed for cellulose I-hydrazlne complexes over the years. Some of this diversity is almost certainly due to poor quality data, which can be Indexed in different ways. Nevertheless, visual comparison shows that our patterns are significantly different from those published previously, which probably reflects the fact that we used hydrazine containing no more than 3% water, as compared to up to 40% in earlier work. So far we have prepared three different cellulose Il-hydrazlne complexes, two for Fortisan (designated A and B) and one for Mercerized ramie. There may be some rationale for this complex A has only been obtained using anhydrous hydrazine, and the Fortisan and Mercerized ramie have different morphologies. However, it seems likely that all three complexes can be formed by both specimens once the preparation conditions are better understood. 

N. Suizu, T. Uno, K. Goda, and J. Ohgi, Tensile and impact properties of fully green composites reinforced with mercerized ramie fibers, /. Mater Sd. 44, 2477-2482 (2009). 

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