Caracterização de compósito fibra de Curauá/poliuretano derivado de óleo de mamona sem agentes de acoplamento

Abstract

The development of new composite materials made from renewable and biodegradable sources and without methods that involve solvents or treatment of the fibers gets a lot of attention from automotive and aeronautic industries due to the good mechanical properties, low density, low cost of the raw material and the great influence that the sustainable development has on the economy. In this work, it was proposed the analysis of the mechanical properties of composite materials made from curauá fibers and polyurethane derived from castor oil, without coupling agents, in order to achieve the composite with the best mechanical properties for industrial applications. Curauá fibers have shown better properties than other natural fibers used in composites, like sisal and jute. The polyurethane derived from castor oil, compared to the same material derived from petroleum, has shown advantages like biodegradability, the ease of obtaining the raw material and its low cost. The fibers used in this work were short and randomly oriented inside the matrix. Three different pressures were employed in the casting: 4.3 MPa, 2.6 MPa and 1.3 MPa. Other parameter changed were fiber/matrix mass proportion (50%, 60% and 70% fiber) and casting temperature (room temperature, 60°C, 75°C and 90°C). The evaluation of the obtained composite materials was made with three point flexural tests, swelling tests, thermogravimetric analysis (TGA) and scanning electron microscope (SEM). A mass proportion of 70% had low flexural strength when compared to the other proportions. The composites showed flexural strength between 19 and 55MPa, for casting pressures of 4,3MPa and 2,6MPa. A increase in casting pressure and temperature caused a rise in flexural strength for samples made in heated cast. The swelling test showed a volume increase of 9%. It is concluded that it is possible to obtain high strength green composites with the materials and methods analyzed in this work.