Polysaccharides significance

The significance of phenoxy anions is well recognized in the isolation of kraft and other water-insoluble technical lignins by acid precipitation. The ioniza tion of phenoHc hydroxyl groups coupled with the reduction of molecular size renders native lignin soluble in the aqueous pulping solution, thus enabling its separation from the polysaccharide components of wood. 

Significant protection of mice by several polysaccharides other than glucan isolated from S. cerevisiae has been described (209). A 2.16-fold protection in the LD q q is observed for one modifier, MNZ, when given 15 min prior to irradiation. Glucan protects 2.25-fold in this same protocol. Many of these polysaccharides may act through activation of the complement system, rather than directiy on ceHs. 

For a polydisperse solution—the hallmark of solutions of polysaccharides—s (and s ) will be a weight average [30,38,39]. If the solution contains more than one discrete (macromolecular) species—e.g. a mixture of different polysaccharides, the polydispersity will be manifested by asymmetry in the sedimenting boundary or, if the species have significantly different values for S2o,w. discrete boundaries are resolved (Fig. 2b [29]). 

Another major drawback of polysaccharides is their hydrophilic nature leading to low degrees of adhesion between fiber and matrix [11]. Moisture absorption takes place by three types of mechanisms namely diffusion, capillarity, and transport via micro cracks [2]. Among the three, diffusion is considered to be the major mechanism. Water absorption largely depends on the water-soluble or hygroscopic components embedded in the matrix, which acts as a semipermeable membrane. While, fiber/matrix adhesion and fiber architecture also affect the moisture absorption. The results of the water sorption experiment showed an interesting trend. The extent of water uptake was not very significant and also did not increase linearly with amount of filler (Table-2). 

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