NEPOMUCENO, N. C.; http://lattes.cnpq.br/4791142122621787; NEPOMUCENO, Neymara Cavalcante.
Résumé:
Cellulose Nanofibrils (CNF) have a wide range of applications, since they have high
aspect ratio, high crystallinity and mechanical properties besides the important
properties of cellulose as low density, biodegradability and come from a renewable
source. Polyaniline (PANI) alone has insufficient mechanical properties for applications
such as films, but with the incorporation of nanoparticles it is possible to improve such
properties. Thus, the polymerization of aniline in the presence of cellulose nanofibrils
becomes an alternative in obtaining conductive particles with adequate mechanical
properties presenting advantages over pure PANI. Therefore, this work aims to join
two types of materials: cellulose nanofibrils (CNF), because they have the capacity to
be worked in aqueous suspension and in the form of gels, serving as a "skeleton" of
the nanocomposite, and polyaniline, which in turn will assign electrical properties to
the material developed. The thermal stability, particle size and other physico-chemical
characteristics of this material were evaluated according to the different PANI / CNF
ratios. In addition, the syntheses of the pure polyaniline and the PANI / CNF
nanocomposite were monitored through the open circuit potential (Voc). The results
show that the polymerization time decreases as a function of the increase of the PANI
ratio in the nanocomposite, due to the favoring of the polymerization mechanisms.
Meanwhile, particle size increases at higher concentrations of PANI, an indication that
higher concentration polymerization provides larger polyaniline agglomerates sites.
The stability is presented as moderate due to the addition of cellulose nanofibrils, since
the pure polyaniline does not present very low stability in aqueous suspension as
verified by Zeta potential measurements. Conductivity tests showed values close to
those found in the literature (10-1 S.cm-1 samples with 40% polyaniline), indicating
that the addition of cellulose nanofibrils did not decrease the electrical properties.