Influence of graphene oxide on ‘in situ’ preparation of nanocomposites with polyvinyl butyral

Resumo

In this work, polyvinyl butyral (PVB) nanocomposites reinforced with 0.5 to 2.5 wt% of graphene oxide
(GO) were synthesized via „in situ‟ polymerization. PVB was obtained by condensation of hydroxyl groups
of polyvinyl alcohol (PVA) with butyraldehyde (BU) Thermogravimetric analyzes (TGA) showed the increase
in the thermal conductivity of the nanocomposites compared to PVB. FTIR results showed the conversion
of PVA to PVB, but no changes in the spectrum were observed for nanocomposites. Nuclear magnetic
resonance spectroscopy (1H NMR) shows a change in the degree of acetalization of PVB with the presence of
the nanoparticles. When the increase in the concentration of GO, a decrease in the degree of acetalization of
PVB is observed. The differential scanning calorimetry (DSC), show a decrease in Tg values, probably
caused by the change of degree of acetalization. The results of the Raman spectroscopy analysis show upshift
in the G band up to 20 cm-1, associated with the presence of van der Walls interaction between the GO and
PVB and the mechanical compression phenomena of the GO nanoparticles are compressed in the „bulk‟ of
polymer. Thus, it was observed that the „in situ‟ polymerization process contributed to the formation of a
colloid between GO and water used as solvent in the synthesis. The formation of this colloid helped to improve
the interfacial interaction between GO and PVB. However, the presence of GO also contributed to
change the degree of acetalization of PVB, as it decreased the condensation of some hydroxyl groups of the
precursor PVA degree of acetalization.
Keywords: polyvinyl butyral, graphene oxide, nanocomposites.