Daniella Cibele Bezerra

Síntese de ferrita NiFe2O4 e sua incorporação em compósitos de poliamida 6: Parte 1: caracterização estrutural por drx e mev dos pós e dos compósitos

As ferritas geralmente sao absorvedoras de radiacao eletromagnetica e apresentam a versatilidade de poderem ser manufaturadas com geometrias diferentes, e usadas na forma de ferritas policristalinas (corpo sinterizado) ou de compositos de ferrita (adicao de po em matriz apropriada). A poliamida 6, por sua vez, pertence a uma classe de polimeros atraentes para aplicacoes em engenharia devido a combinacao de propriedades como: estabilidade dimensional, boa resistencia ao impacto sem entalhe e excelente resistencia quimica. O objetivo deste trabalho foi sintetizar pos de ferrita NiFe2O4, e avaliar a adicao destes em concentracoes de 10, 30, 50 e 60% em massa a uma matriz polimerica de poliamida 6 usando um misturador da Haake Blucher, para obter compositos de poliamida 6/NiFe2O4. Os pos e os compositos foram caracterizados por difracao de raios X (DRX) e microscopia eletronica de varredura (MEV). Os difratogramas de raios X mostraram picos caracteristicos da poliamida 6 e da ferrita. Por MEV foi observada a formacao de aglomerados grandes para a concentracao de 60% e, uma grande quantidade de poros. Para a concentracao de 10%, as particulas ficaram mais dispersas, com menos aglomerados e menos poros no composito.

Evaluation of the Hydrophobicity on Silicon Rubber Coating with Loads of Alumina Trihydrate and Nanosilica for Use in Electrical Insulation Coatings

This study aims to evaluate the hydrophobicity of vulcanized silicone rubber coatings at room temperature (RTV SR) with loads of alumina trihydrate (ATH) and nanosilica (NS) in the polymeric silicone rubber matrix, in order to obtain coatings ATH/NS/RTV SR to cover the surface of glass electrical insulators. The coatings were characterized by scanning electron microscopy (SEM), testing in salt spray chamber, loss test and recovery of hydrophobicity. These coatings showed varying sizes of agglomerates and heterogeneous distribution of particles within the matrix RTV SR. In the test in salt spray chamber smaller leakage current values was observed for the insulator coating with the ATH/NS loads. In the loss and recovery of the hydrophobicity test the best result was observed for insulating load RTV SR / 20: 1 (ATH: NS).

Rheological Study of Polyamide 6/Waste Styrene-Butadiene Rubber (SBR) Blends

The application of polyamides is limited by low impact performance when notched in room temperature conditions. This situation is worsening, especially for use in temperatures below zero degrees Celsius. One way to outline this limitation is to prepare polymer blends where the dispersed phase is an elastomer, and then classified as an immiscible blend. Therefore, this study aims to develop polyamide 6/waste styrene-butadiene rubber (SBR) blends, with addition of compatibilizer PP-g-MA and PE-g-MA in order to achieve a balance between stiffness and tenacity. The results obtained with the rheological study showed that mixtures of PA6/PE-g-MA presented the best results in comparison with mixtures of PA6/PP-g-MA, indicating that there was probably a reaction between the components, which may allow a better dispersion and thus can achieve better properties.

Development of Polyamide 6/Ferrite Composites for Absorbers of Electromagnetic Radiation

Composites consist of a mixture or combination of the two or more, micro or macro constituents that differ in shape and chemical composition and, in essence, are insoluble in one another. The polyamide is a polymer that presents dimensional stability, good resistance to impact without notch and excellent chemical resistance. Already the ferrites are absorbers of electromagnetic radiation and have versatility to be used as a composite of ferrites. The composite of polyamide6/ferrite was obtained by mixing 10 and 30wt.% of ferrite added to polyamide 6 in a Torque Rheometer Haake. The objective of this work was to develop of polyamide6/ferrite composites to be used as absorbers of electromagnetic radiation. The results were very promising and showed that occurs interaction between the ferrite and polyamide6.