Lignocelluloses components

Benner, R., and R. E. Hodson. 1985. Microbial degradation of the leachable and lignocellulosic components of leaves and wood from Rhizophora mangle in a tropical mangrove swamp. Marine Ecology Progress Series 23 221-230. 

If hydroxyl reactivity is selected as the preferred modification site, the chemical must contain functional groups that will react with the hydroxyl groups of the lignocellulosic components. This may seem obvious but there are several failed reaction systems in the literature using a chemical that could not react with a hydroxyl group. 

The moisture present in the lignocellulosic is another consideration in the reaction conditions. It is costly to dry lignocellulosics to less than 1 % moisture, but it must be remembered that the OH group in water is more reactive than the OH group available in the lignocellulosic components, i.e., hydrolysis is faster than substitution. The most favorable condition is a reaction that requires a trace of moisture and the rate of hydrolysis is relatively slow. 

The hydrophobic nature of the reagent needs to be considered. The chemical added to the lignocellulosic should not increase the hydrophilic nature of the lignocellulosic components unless that is a desired property. If the hydrophilicity is increased, the susceptibility to microorganism attack increases. The more hydrophobic the component can be made, the better the substituted lignocellulosic will withstand dimensional changes in the presence of moisture. 

In summary, the chemicals to be laboratory-tested must be capable of reacting with lignocellulosic hydroxyls under neutral or mildly alkaline or acidic conditions at temperatures below 150°C. The chemical system should be simple and capable of swelling the structure to facilitate penetration. The complete molecule should react quickly with lignocellulosic components yielding stable chemical bonds, and the treated lignocellulosic must still possess the desirable properties of untreated lignocellulosics. 

Decomposition rate constants are negatively correlated to the total fiber content of the organic snbstrate bnt not well correlated to individual components such as cellulose, hemicellulose, and lignin. A field and laboratory study by Moran et al. (1989) measured the decomposition rates of whole litter and the lignocellulose components of the litter for the emergent macrophytes S. alterniflora and C. walteriana. Decomposition of individual carbon fractions varied with the rate of decomposition in the order of cellulose > hemicellulose > lignin (Figure 5.38, Moran et al., 1989). 

Moreover, obtaining composites filled with the lignocellulosic component with desired strength properties require consideration of many factors having an effect on the final macroscopic properties. The objectives of this study is to analyze the effect of the following factors such as the adhesion between the components, filler content, fiber length of fibrous filler, filler distribution, and the effect of processing parameters on the mechanical properties of composites. 

The literature reports also other methods for modification of lignocellulosic components to improve interphase adhesion. These comprise reactions with triazine derivatives [87], -octadecyl vinyl-sulfone [87], potassium permanganate [86, 88], as well as dicumil or benzoyl peroxides ([89] Jayamol [90]). Processing with peroxides in addition to significant improvement of mechanical properties of composites is also responsible for making processing of composite materials easier [86,91,92]. 

Figure 1. Schematic of Procedure Used For Specifically Radiolabeling Lignocellulosic Components of Vascular Plants.

Nakanishi, S. C., Gon9alvesa, A. R., Rocha, G., Ballinas, M. L., and Gonzalez, G. 2011. Obtaining polymeric composite membranes from lignocellulosic components of sugarcane bagasse for use in wastewater treatment. Desalination Water Treat. 27 66-71. 

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