Papers Proceedings »
Characterization of acrylic acid-co-acrylamide hydrogels reinforced with TEMPO-oxidized Agave tequilana bagasse cellulose nanofibers
Hydrogels are polymeric materials with potential applications in several key areas such as biomedicine, agriculture, and water purification. However, one of their main disadventages is their low mechanical properties. During the last decades many efforts been done to improve the stiffness and mechanical resistance of hydrogels. One of the most successful of the proven techniques to improve such mechanical properties consists in adding polymer particles into the hydrogel network (e.g. inorganic clay and carbon nanotubes), forming an interconnected polymer network, and double-network structures. In this work, acrylic acid-co-acrylamide hydrogels (ratio of 80:20) were reinforced with Agave tequilana Weber blue variety bagasse cellulose nanofibers, using concentrations of 0.15, 0.35 y 0.55 wt%. Nanofibers extracted from both bleached and unbleached cellulose were employed. In order to improve the dispersion of nanofibers inside the hydrogel matrix, the nanofibers were subjected to TEMPO oxidation. FTIR spectra of cellulose nanofiber-reinforced hydrogels did not show evidence of formation of new bonds between the hydrogel matrix and the nanofibers. Swelling kinetics were followed for 3 months and show that the swelling capacity increases when the content of nanofibers also increases. Nevertheless, a reduction of the swelling capacity occurred when the nanofiber concentration was 0.55 wt%. The highest values of the Young´s modulus in the compression tests were from hydrogels with 0.35 wt% of unbleached nanofibers. The swelling kinetics were adjusted to a pseudo-second order Schott model. SEM micrographs showed that the pores of lyophilized hydrogels containing TEMPO oxidized cellulose nanofibers are well defined in size and also are better distributed in the matrix in comparison with hydrogels with non TEMPO-oxidized nanofibers.