Byong-Wa Chun

The development of cement and concrete additive: based on xylonic acid derived via bioconversion of xylose.

The present work attempted to utilize xylose by converting it to an aldonic acid. In the present study, xylose was converted to xyloni acid by using commercial glucose oxidase enzyme, palladium catalysis, and microbial bioconversion. The enzyme conversion was successfully done using a commercial glucose oxidase. The microbial conversion with Gluconobactor oxydans proceeded even with the presence of a large amount of lignosulfonate. Thus obtained xylonic acid products were evaluated as a cement dispersing agent in cement and concrete tests. It was found that xylonic acid is approximately twice as effective as lignosulfonate. Xylonic acid can be effectively utilized in concrete water reducer application.

Preparation and characterization of organic-soluble optically transparent polyimides from alicyclic dianhydride, bicyclo[2.2.2]-oct-7-ene-2,3,5,6-tetracarboxylic dianhydride

Abstract Organic-soluble optically transparent polyimides were prepared from alicyclic dianhydride monomer, bicyclo[2.2.2]-oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (BCDA). BCDA gives soluble polyimides with diamines containing at least one flexible linkage such as ether, methylene and sulfide. The polyimides have glass transition temperatures above 350°C and a thermal decomposition temperature of 450°C in an inert atmosphere. The polyimides form a tough film with an ultra-violet cut-off between 300 and 400 nm, which is comparable to that of a fluorinated polyimide.

The development of cement and concrete additive

The present work attempted to utilize xylose by converting it to an aldonic acid. In the present study, xylose was converted to xyloni acid by using commercial glucose oxidase enzyme, palladium catalysis, and microbial bioconversion. The enzyme conversion was successfully done using a commercial glucose oxidase. The microbial conversion with Gluconobactor oxydans proceeded even with the presence of a large amount of lignosulfonate. Thus obtained xylonic acid products were evaluated as a cement dispersing agent in cement and concrete tests. It was found that xylonic acid is approximately twice as effective as lignosulfonate. Xylonic acid can be effectively utilized in concrete water reducer application.