Celluloses ball milling studies

Interestingly, the ball-milling studies of microcrystalline cellulose by Nakai (Table 4 [53]) have shown that the Wm values obtained from water sorption... 

Two series of cellulose samples, Avicel and Whatman CFll cellulose ball-milled powders with different crystallinity are studied below Tg temperature by using positron annihilation lifetime spectroscopy. A good correlation is found between ortho-positronium formation probability and crystallinity as measured by Fourier transform -infrared spectroscopy. Sub-nanometer hole distributions are found to be narrowed as a function of milling time. These are interpreted in terms of microstructural changes of cellulose. 

Mintova et al. studied deposition of zeolite A on various cellulose fibers pretreated chemically and/or mechanically [151]. It was shown that the amount of zeolite deposited was controllable by suitable fiber pretreatment with ball-milling or with diethyl ether under ultrasonic action. The reactive high-concentration hydroxyl groups on the structurally loosened celluloses seem to interact with aluminosilicate species and thus promote the formation of nuclei for zeolite crystallization. Pretreatment of natural cellulose fibers with alkali provides another simple route for anchoring preformed zeolite crystallites onto the cellulose surface. 

Mechanochemically Initiated Graft Copolymerization. According to the ESR study, it is clear that mechanoradicals were generated in cellulose either by means of mechanical cutting or ball milling. These mechanoradicals may be utilized as reaction sites for the initiation of vinyl polymerization which would result in graft copolymerization of cellulose. Based on this principle, the ability of cellulose mechanoradicals to initiate copol3nnerization was pursued. 

Deters [20] vibromilled a blend of cellulose and cellulose triacetate. The acetic acid content of cellulose acetate decreased with grinding time (40 hr) while that of the cellulose increased, suggesting the formation of a block or graft copolymer or of an esterification reaction by acetic acid developed by mechanical reaction. Baramboim [21] dissolved separately in CCI4 polystyrene, poly(methyl methacrylate), and poly(vinyl acetate). After mixing equal volumes of solutions of equivalent polymer concentration, the solvent was evaporated at 50°C under vacuum and the resultant product ball-milled. The examination of the ball-milled products showed the formation of free radicals which copolymerized. Systems of polyethylene plus polyester have also been studied [219]. 

To study the structure of NCD hy WAXS method, samples of amorphized cellulose are required. These samples can be prepared by ball-milling, saponification of cellulose acetate in non-water alkali solutions, etc. (Jeffries, 1968). The typical X-ray diffractogram of amorphous cellulose has a wide peak with maximum at 20 = 20-20.5° (Fig. 7.9). Using the modified Scherrer s equation for amorphous pol5miers with the shape factor K = 1.8, an average size of partially ordered mesomorphous clusters of NCD can be estimated = 1.8-1.9 nm. Average Bra s... 

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... 

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