Biodegradable intelligent packagings

LUCÍA M. FAMÁ; CELINA BERNAL; SILVIA GOYANES

, Los Cocos, Córdoba, Argentina

Congreso; V Argentine – Chilean Symposium, ARCHIPOL 09; 2009

It is well known that carbon nanotubes have excellent mechanical, thermal and electrical properties. Besides, they have a high aspect ratio, which makes them ideal materials to employ as sensors. For example, starch-nanotubes composites with MWCNTs concentrations reaching electrical percolation could be used as humidity sensors because the electric conductivity of the nanotubes changes when water molecules are absorbed on their walls. In order to obtain electrical percolation, MWCNTs should be well dispersed in the starch matrix. It was proposed that wrapping of nanotubes could help in this way. Star et al. (2004) used an aqueous solution of starch-iodine complex to wrap carbon nanotubes. When iodine is mixed with starch and water preorganizes the backbone of the amylose into a helical conformation and makes its hydrophobic cavity accessible to a single carbon nanotube or bundles thereof. On the other hand, the film of starch glycerol is a polymer electrolyte and then a mechanism of ionic conduction is possible through it. The water molecule absorbed on film surface splits to produce protons (H+) and a higher number of protons is produced when the sensing material is exposed to higher humidity in the testing system (Fuke et al., 2009). The iodine added to the starch-water system produces an increment in ionic conductivity. In this work, a methodology to develop new nanocomposites based on starch and carbon nanotubes is reported. The capability of these nanocomposites as humidity sensors is also evaluated.