Influência do tratamento superficial da nanocarga nas propriedades mecânicas de curta e longa duração de um nanocompósito de PEEK/nHA
Abstract
In this dissertation the mechanical properties of short and long term of
PEEK/nHA nanocomposites with potential application as orthopedic implants
were studied. The nanohydroxyapatite (nHA) was surface-treated with the
coupling agent aminoethylaminopropyltrimethoxysilane (AEAPTS). After
treatment, the nanoparticles were mixed with the polymeric matrix of poly (ether
ether ketone) (PEEK) in a twin screw extruder. Subsequently specimens of the
nanocomposite were injection molded. These specimens were subjected to
mechanical tests to have their properties compared with the pure polymer and
the nanocomposite with the pure nHA. First, tensile tests were conducted;
through these analyses, it was found the stress and strain at break increased.
The presence of the silane increased the fatigue life of the nanocomposite
suggesting a higher interaction between the matrix and the nanofiller. The
impact tests confirmed the higher resistance of the sample with silanized nHA. It
was concluded that the silanization of the nHA was effective, strengthening the
interface PEEK/nHA; however, silane molecules also plastified the polymer
matrix. The injected test specimens were subjected to annealing. The objective
was to determine how the increase in crystallinity induced by annealing
influenced the mechanical properties. After the annealing, the presence of the
silane did not cause significant changes in the mechanical behavior of the
material. Analysis of scanning electron microscopy (SEM) and dynamic
mechanical analysis (DMA) were done in order to characterize the structure of
the nanocomposites. The morphology observed in the micrographs was
correlated with the dynamic mechanical properties. It was concluded that the
nanocomposite with silanized nHA besides having elastic modulus behavior
similar to natural bone, also had a more homogeneous structure than the
nanocomposite with pure nHA.