Ball-milled cellulosic materials

More difficult task is the determination of crystallinity degree of native cellulose located directly in the plant material. To do this, the samples of artificial mixtures containing cellulose, lignin, and hemicelluloses were prepared moreover, the crystalline D-cellobiose was used as crystalline standard and the ball-milled plant material as amorphous standard. Then, X-ray diffractograms of these samples were recorded (loelovich et al., 1989]. As a result, the following equations for calculation of crystallinity degree of native cellulose were derived ... 

The effect of ball milling is similar in all cases. Within the first 10 min of milling, the 002 reflection is considerably broadened and appears slightly shifted to a smaller angle. This apparent shift is probably the result of the superposition of the broadened 002 peak upon the rising, broad, amorphous peak which centers about 18.5° (2 ). As ball milling continues, the crystalline characteristics decrease and the amorphous characteristics increase. After about 1 hr of milling time, the crystalline characteristics of all the cellulosic materials have disappeared. 

Solid-state cellulose can also be noncrystalline, sometimes called amorphous. Intermediate situations are also likely to be important but not well characterized. One example, nematic ordered cellulose has been described [230]. In most treatments that produce amorphous cellulose, the whole fiber is severely degraded. For example, decrystallization can be effected by ball milling, which leaves the cellulose as a fine dust. In this case, some crystalline structure can be recreated by placing the sample in a humid environment. Another approach uses phosphoric acid, which can dissolve the cellulose. Precipitation by dilution with water results in a material with very little crystallinity. There is some chance that the chain may adopt a different shape (a collapsed, sixfold helix) after phosphoric acid treatment. This was concluded because the cellulose stains blue with iodine (see Figure 5.12), similar to the sixfold amylose helix in the starch-iodine complex. 

The Substrate and Its Modification. Solka Floe—SW40A (Brown Co., Berlin, N. H., USA), a wood (spruce) pulp commonly used as a filter aid has been used as a basic cellulosic material for susceptibility tests and saccharification studies. The material was milled dry in a laboratory porcelain pot mill using glazed porcelain balls of 1 inch (2.65... 

The cathode material, Lao.. i(Sro,4oFeo.8oCoo.2o03.6 was synthesized by spray drying method. After calcination and ball-milling, the cathode powder was screen printed on a 5x5 cm half cell with a electroMe prepared by sol-gel method, using an ethyl cellulose binder and a terpineol-based solvent . The area of the cathode layers was 4x4 cm with a thickness of about 50 pm. The cathode was dried and no sinter process was carried out before the electrochemical cell test. 

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