Polysaccharides and phenolics of miscanthus belowground cell walls and their influence on polyethylene composites.

Belowground materials from two miscanthus species were ground into fragments for preparing polyethylene composites. Both species show a lot of similarities in terms of polysaccharides, lignin and cell wall-linked p-coumaric and ferulic acids contents. The structures of polysaccharides and of lignins are markedly different in the miscanthus belowground and aboveground biomass. The non-cellulosic fraction of the samples comprises a high level of xylose, with the arabinose to xylose ratio about twice as high as that observed for analogous stem samples, suggesting that belowground arabinoxylans are more substituted than stem ones. The mechanical properties of the belowground miscanthus-polyethylene composites correlate with several of their compositional traits, with similar trends as for plant stem-polyethylene composites with positive correlations for lignin and p-coumaric acid contents and negative correlations for most non-cellulosic sugars.

Ion-interactions as driving force in polysaccharide assembly.

The structure of cellulose is characterised by extensive non-covalent interactions. Recent discussions suggest that hydrophobic interactions between polymer chains also play a significant role in governing cellulose solubility. Surprisingly in almost all cellulose shaping processes, chemical systems or solvents are applied, which base on melts or solutions of charged molecules. Ionic interactions play a significant role in the shaping and modification of cellulose based materials. Dependent on the systems used different principles govern the processes and define the results, e.g. formation of associates with alkali hydroxides, ion-exchange reactions to selectively bind multivalent ions at carboxylic groups, adsorption of dissolved polymers through surface charge neutralisation or metal complex formation, where cellulose takes the role of a polymer ligand system. Presence of charged compounds takes a significant role in cellulose swelling and dissolution, but also directs reassembly of polysaccharide material to solid three-dimensional structures.