ARIMATÉIA, R. R.; http://lattes.cnpq.br/1809891069288443; ARIMATÉIA, Rafaela Reis de.
Abstract:
Poly (methyl methacrylate) - PMMA has been replacing glass in many
applications as it is transparent and more impact resistant. Other advantages are
related to its lower density, which facilitates handling and reduces transportation costs,
as well as not generating shrapnel when broken, compromising safety. It is also one
of the main competitors of Polycarbonate - PC, because it is an inexpensive plastic
with excellent optical properties, good resistance to discoloration and loss of light
transmission. However, PMMA has high flammability, low abrasion resistance, low risk
and low hardness. In order to modify these properties, PMMA composite systems with
three ceramic loads were developed: alumina synthesized (ALS), commercial alumina
(ALC) and vermiculite pyroexpandid clay (VERM). The composites were processed in
a twin-screw extruder and injected molded with 1 and 3% loading. The composites
loaded with the synthesized alumina (ALS) had the highest tensile strength, higher
hardness and better dispersions, however there were no improvements in impact
strength and flammability. The composites loaded with commercial alumina (ALC)
showed a decrease in tensile strength, impact strength, lower values for flammability
and a higher number of clusters in their micrographs, however, there was an increase
in hardness. On the other hand, the composites with the vermiculite clay presented the
best behavior against the impact and flammability tests, with small and well distributed
clusters. The results obtained for the wear index in the abrasion test and the
evaluations made on the basis of the Hoffman risk test were promising. All composites
outperformed the pure PMMA behavior. The composites with ALS showed a gain of
85% in abrasion resistance, composites with ALC around 81% and composites with
vermiculite around 12%. According to the risk assessment proposed by Hoffman, all
the compositions indicated, by the analysis of the morphology of the risks, increase of
the hardness.