Effect of Chitosan and its Derivatives on the Mechanical and Electrical Properties of Paper Sheets

The presented studies are focused on the dependence of paper sheet strength properties on the composition of additives, chitosan, cyanoethyl and carboxymethyl chitosan. Chitosan and its derivatives achieve an improvement in the strength properties of unagged and agged paper sheets. Also, cyanoethyl chitosan improves the dielectric properties of the treated paper sheets. The dielectric study was carried out over a frequency range from 100 Hz to 100 kHz at temperature range from 20 to 140ºC. The variation of permittivity ε′ versus cyanoethyl chitosan content at three different temperatures shows an interesting point at concentration ≈ 0.3%. The variation of ε′ with temperature is explained in the view of the polar groups’ mobility. The variation of ε″ versus the applied frequency is fitted by a superposition of Fröhlich and Havriliak-Negami functions in addition to the conductivity term. These functions could be ascribed to be due to the Maxwell-Wagner effect and the orientation of the large aggregates formed by the addition of chitosan to the paper sheet. Infrared spectroscopy of the chitosan and its derivatives were also examined. New bands were found at 2225 cm-1 and at 1710 cm-1 for cyano- and carboxy groups in the cyanoethyl and carboxymethyl chitosan respectively.