Print version ISSN 0012-7353
NEIRA ARENAS, GUSTAVO; PINILLA PLATA, ALIRIO and HENAO MARTINEZ, JOSÉ ANTONIO. CHITOSAN-MODIFIED BENTONITIC CLAY FOR BIODEGRADABLE COMPOSITE MATERIALS. Dyna rev.fac.nac.minas [online]. 2011, vol.78, n.167, pp. 59-65. ISSN 0012-7353.
The modification of a Colombian montmorillonite-type clay with a policationic biopolymer -chitosan- was studied, and the effect of the molecular weight of the modifier on the effectiveness of the modification treatment was evaluated. A Na-montmorillonite clay was used as starting material, which was subjected to a specially developed modification treatment with different concentrations of high and low-molecular weight chitosan. Samples of modified clay were analyzed by X-Ray Diffraction, Fourier Transform Infrared Spectroscopy (FTIR), and Thermogravimetric Analysis (TGA) in order to identify the possible effects of the modification treatment on the structure of the clay. The results showed a direct relation between the increase in the interlayer spacing of the modified clay and the concentration of chitosan, finding a maximum increase of 1,559 nm for a 2:1 ratio of low molecular weight chitosan:clay. In general, a greater interlayer separation of the clay was detected when low-molecular weight chitosan was used as modifier, compared to that of high-molecular weight chitosan, even though an effective integration of modifying agent to the structure of the clay was observed in both cases. IR analysis of the modified clay made evident the presence of CH, NH3+, CH2 y NH2 from the chitosan, while TG analysis suggested some degree of hydrofobicity linked to the presence of chitosan, these aspects being of great importance for the application of these materials as reinforcement in biodegradable polymeric films.
Keywords : clay; montmorillonite; chitosan; organobentonite; biopolymers; composite materials.