Efeito de diferentes cargas orgânicas em cimentos resinosos experimentais
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Data
2016-02-19
Autores
Souza, Ana Carolina de Oliveira [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
O objetivo deste trabalho foi avaliar o comportamento de cimentos resinosos experimentais reforçados com fibras de nylon (N6) e de nylon com nanotubos de carbono de parede múltipla (N6+CNT). A hipótese testada foi de que a distribuição das fibras seria capaz de melhorar as propriedades mecânicas dos compósitos, resultando em um efetivo reforço dos cimentos resinosos. As fibras foram produzidas pela técnica da eletrofiação para caracterização e para a imersão na matriz resinosa e posterior obtenção das partículas, utilizadas em quatro diferentes frações de massa (2,5; 5,0; 10,0 e 20,0%). Também foi preparado um grupo controle, sem adição de partículas e um grupo matriz, onde as partículas sem nanofibras foram utilizadas. Foram realizados os testes de resistência à flexão, módulo de elasticidade, contração de polimerização, grau de conversão e espessura do cimento. Também foi realizada a caracterização das fibras obtidas. Os resultados mostraram que todos os grupos apresentaram espessura de cimentação aceitáveis de acordo com a norma ISO 4049. As fibras de N6+CNT apresentaram distribuição bimodal, com fibras de maior diâmetro em relação as fibras de N6. As partículas de todos os grupos mostraram-se irregulares, aglomeradas e com grande variação de tamanho, entretanto as fibras de N6 +CNT mantiveram-se mais alinhadas, o que pode ter levado aos maiores valores de resistência, de maneira que as menores concentrações (2,5 e 5,0%) parecem ser mais favoráveis. O acréscimo de partículas sem nanofibras foi capaz de aumentar a resistência dos cimentos resinosos devido a um significativo aumento do grau de conversão. Com relação aos valores do módulo de elasticidade, todos os grupos apresentaram valor de módulo estatisticamente maior, quando comparados com o grupo controle, porém não apresentaram diferenças entre si em relação ao tipo e concentração de partícula. Podemos concluir que com a utilização de cargas orgânicas de nylon associadas a nanotubos de carbono foi possível obter a melhoria das propriedades mecânicas dos cimentos resinosos.
The aim of this study was to evaluate the behavior of experimental resin cement reinforced with nylon fibers (N6) and nylon with multiwalled carbon nanotubes (CNT + N6). The hypothesis was that the distribution of fibers would be able to improve the mechanical properties, reinforcement the resin cements. The fibers were produced by electrospinning technique for characterization and for immersion of fibers in the resin matrix and obtainment of the particles used in four different mass fractions (2.5, 5.0, 10.0 and 20.0%). It was also prepared a control group without addition of particles and the matrix group, where the particles without nanofibers were used in different concentrations to eliminate the effect of pre-polymerized matrix. Were tested the flexural strength, elastic modulus, shrinkage, degree of conversion and thickness of the cement. It also were characterized the fiber obtained. The results showed that all groups had acceptable cement thickness in accordance with ISO 4049 and that the selected parameters for the electrospinning, the fibers showed no beads. The fibers with N6 + CNT had a bimodal distribution, with the larger diameter fibers than the N6 fiber. The particles of all groups were irregular, agglomerated and with great size variation, however the fibers N6 + CNT remained more aligned, which might explain the higher values of flexural strength and the lower concentrations (2.5 and 5.0%) appear to be more favorable. The particles without fibers was able to increase the resistance of the resin cement due to a significant increase in the degree of conversion. All groups showed statistically higher elastic modulus value than the control group, but did not differ among themselves with respect to the type and particle concentration. It is possible to conclude that the use of organic fillers with nylon and carbon nanotubes improved mechanical properties of the resin cements.
The aim of this study was to evaluate the behavior of experimental resin cement reinforced with nylon fibers (N6) and nylon with multiwalled carbon nanotubes (CNT + N6). The hypothesis was that the distribution of fibers would be able to improve the mechanical properties, reinforcement the resin cements. The fibers were produced by electrospinning technique for characterization and for immersion of fibers in the resin matrix and obtainment of the particles used in four different mass fractions (2.5, 5.0, 10.0 and 20.0%). It was also prepared a control group without addition of particles and the matrix group, where the particles without nanofibers were used in different concentrations to eliminate the effect of pre-polymerized matrix. Were tested the flexural strength, elastic modulus, shrinkage, degree of conversion and thickness of the cement. It also were characterized the fiber obtained. The results showed that all groups had acceptable cement thickness in accordance with ISO 4049 and that the selected parameters for the electrospinning, the fibers showed no beads. The fibers with N6 + CNT had a bimodal distribution, with the larger diameter fibers than the N6 fiber. The particles of all groups were irregular, agglomerated and with great size variation, however the fibers N6 + CNT remained more aligned, which might explain the higher values of flexural strength and the lower concentrations (2.5 and 5.0%) appear to be more favorable. The particles without fibers was able to increase the resistance of the resin cement due to a significant increase in the degree of conversion. All groups showed statistically higher elastic modulus value than the control group, but did not differ among themselves with respect to the type and particle concentration. It is possible to conclude that the use of organic fillers with nylon and carbon nanotubes improved mechanical properties of the resin cements.
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Palavras-chave
Cimentos de resina, Fibras, Eletrofiação, Contração de polimerização, Módulo de elasticidade, Nanofibras, Resistência à flexão, Resin cement, Fibers, Electrospinning, Shrinkage, Elastic modulus, Flexural strength