New pretreatment methods were developed for separating hemicellulose, cellulose, and lignin from biomass for their efficient use in the thermo-chemical conversion of each component. One method is basically a two-step process. Biomass treated in hot water at 180 °C was extracted in a flowing stream of water/acetone mixture under 10 MPa at 230 °C. Through the hot water treatment, hemicellulose in biomass was successfully recovered as saccharides, leaving lignin and cellulose as a solid. Through the sequential extraction by the water/acetone solvent, lignin was depolymerized into the water/acetone-soluble compounds and the residual cellulose was partly dehydrated. The other method is a one-step process, in which biomass was directly extracted in 50% water/acetone solution at 200 °C using a batch reactor, and the residue was pure cellulose. The proposed methods were expected to be new routes for converting low-grade resources into valuable chemicals.

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This paper investigates the effect of rheological behavior on dynamics of bubble coalescence. In situ observations on polymers with different rheological behaviors were conducted to study coalescence dynamics. Four patterns of interface deformation were observed. Deformation during coalescence was analyzed by applying image‐processing schemes and rheological models to the in situ observations. Polymer with Newtonian behavior showed nucleation and coalescence of spherical bubbles that created a planar interface. The planar interface was deformed by a combination of biaxial and planar elongational flows. Coalescence in polymers with non‐Newtonian behavior is characterized by penetration with a parabolic shaped interface. The deformation of parabolic interface was due to biaxial elongational flow. However, the interface deformation of the polymer with cross‐linked structure was due to an integration of biaxial and elongational flow. Further, cross‐linking was also observed to have an effect on coalescence time. POLYM. ENG. SCI. 46:680–690, 2006. © 2006 Society of Plastics Engineers