Cellulose high-temperature transformation

The same phenomena were observed for soda celluloses. Na-oellulose Ij prepared from the I family under conditions of low swelling (high temperature or with stretching) could be converted to cellulose I with hot water. Na-cellulose Ijj prepared from cellulose II under the same conditions was converted to cellulose II (7-10). In ordinary mercerization of native cellulose a mixture of Na-cellulose Ij and Ijj was obtained both decomposed to cellulose II with cold water. Na-cellulose Ij was transformed irreversibly into Na-cellulose Ijj. 

Treatment with hquid ammonia or with certain amines such as 1,2-diaminoethane (ethylenediamine, EDA) allows the preparation of cellulose El from either cellulose I (which leads to the form cellulose IIIi) or cellulose II (which leads to toe form IIIn). Cellulose Hi treated at high temperature in glycerol is transformed into cellulose IV. Here again two types exist cellulose fVi and IVn, respectively, obtained from cellulose IIIi and Illn. It is generally accepted that cellulose IVi is a disordered form... 

Yamamoto H, Horii F (1993) CPMAS carbon-13 NMR analysis of the crystal transformation induced for Valonia cellulose by annealing at high temperatures. Macromolecules 26 1313-1317... 

Wu RL, Wang XL, Wang YZ, Bian XC, Li F (2009) Cellulose/soy protein isolate blend films prepared via room-temperature ionic liquid. Ind Eng Chem Res 48(15) 7132-7136 Yamamoto H, Horii F (1993) CPMAS carbon-13 NMR analysis of the crystal transformation induced for Valonia cellulose by annealing at high temperatures. Macromolecules 26 (6) 1313-1317... 

Cellulose IV, is obtained by annealing cellulose III, at high temperature (260 °C). The crystal transformation map of a series of cellulose is summarized in Figure 3.7. 

The preparation of cellulose III is realized with ammonia treatment and allows to obtain the form cellulose IIIi or the form IIIn from to cellulose I and cellulose II, respectively. Cellulose III can be transformed into cellulose IV after treatment at high temperature in glycerol cellulose IVj and IVn obtained from cellulose IIIi and HIn, respectively. After relative recent studies by electron diffraction [47], it is now accepted that cellulose IViis a disordered form of cellulose I (native cellulose form). This allomorph, at native state, may be observed in some mushrooms but also in primary cell walls of cotton [48]. 

Wood plastics composites have been successfully and rapidly developed in North America to produce a market of 690,000 tonnes, and they are now becoming more popular in Europe and Asia. Compatibilisers improve the water resistance and rot resistance and transform the mechanical properties, particularly the strength. They also improve the heat distortion temperature. This is because of the poor compatibility between polar cellulosic fibres and nonpolar polyolefins. In practice many manufacturers do not yet use compatibilisers because of their high cost. 

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