New insulating particleboards prepared from mixture of solid wastes from tissue paper manufacturing and corn peel.

New composite boards with low-thermal conductivity produced from a mixture of solid wastes from tissue paper manufacturing (solid waste TPM) and corn peel have been developed. The effects of solid waste TPM/corn peel ratio on the properties of the boards were investigated and the possibility of using recycled polystyrene packaging foam as a laminating agent to improve the quality of the boards was also evaluated. Our results show that the density of the particleboards decrease with increasing the amount of corn peel added in the mixture, leading to a decrease in thermal conductivity of the final product. In contrary, larger amount of solid waste TPM added in the mixture produced stronger boards. The lamination of recycled polystyrene on the surface of particleboards improves the mechanical properties and reduces the thickness swelling of the boards. The best improvement in mechanical properties and swelling resistance could be achieved when 15% polystyrene (w/v) was coated on the surface of the boards.

Evaluation of an improved acid hydrolysis-HPLC assay for the acetyl content in chitin and chitosan.

Functional properties of the amino polysaccharides, chitin and chitosan, vary significantly with their acetyl content. The acid hydrolysis-HPLC method offers good accuracy and precision to assay the acetyl content regardless of the solubility of the sample. In this research, the hydrolysis parameters were changed, and the analytical method was counterchecked with other methods. Complete hydrolysis was achieved by mixing chitosan with 1.4 mM oxalic acid and 12 M sulfuric acid followed by treatment at 110 degrees C for 40 min. A sealed glass ampule was used instead of a vacuum hydrolysis tube. The acetic acid released during acid hydrolysis was measured quantitatively by HPLC. A high correlation (r(2) = 0.98) was obtained between the modified HPLC assay and the solid-state (13)C CP/MAS NMR method for the samples of various crustacean sources with a wide range of acetyl contents. The modified HPLC method was also highly correlated (r(2) = 0.99) with the first derivative UV method for soluble chitosan.

Chitosan membrane as a wound-healing dressing: characterization and clinical application.

Chitosan prepared from natural biopolymer chitin and cast into membranes has been tested as wound dressing at the skin-graft donor site in patients. Bactigras, a commonly used impregnated tulle gras bandage, served as a control. Chitosan membrane, prepared with a 75% degree of deacetylation and a thickness of 10 microm, was used in nonmesh or mesh form. The progress in wound healing was compared by clinical and histological examination. Itching and pain sensitivity of the wound dressed area was scored with the use of a visual analogue scale. Mesh chitosan membrane in contrast to the nonmesh membrane allowed blood to ooze into the surrounding gauze. After 10 days, the chitosan-dressed area had been healed more promptly as compared with the Bactigras dressed area. Moreover, the chitosan mesh membrane showed a positive effect on the re-epithelialization and the regeneration of the granular layer. The data confirm that chitosan mesh membrane is a potential substitute for human wound dressing.