چكيده به لاتين
In this study, first, the methods of making natural rubber latex foam mentioned in the sources, were investigated, and the three methods of Dunlop, Talalay and bubbling were introduced and described. Then, according to the available equipment and test conditions and the type of materials used in this study, Dunlop and bubbling methods were selected. Then, according to the results of nanoparticle stability tests in water, alumina nanoparticles were added to the foam matrix in different amounts as a suitable reinforcements. Thermal tests, including thermal decomposition and differential scanning calorimetry, were performed to investigate the effect of nanoparticles on the degradation and vulcanization of foams. Tensile test was also performed to measure the effect of nanoparticles on tensile strength and modulus and other tensile properties of foams. Field emission scanning electron microscopy was used to study the surface morphology of the samples and the density of the samples made by both methods, was measured. The results showed that, with increasing the amount of nano-alumina, tensile strength and modulus, in both methods, has an increasing trend, but the amount of this quantity was higher in the bubbling method than Dunlop method. Alumina nanoparticles also increased the thermal stability of natural rubber latex foam and field emission scanning electron microscopy observations indicated that the cellular structure of the foams was open cell and the structure and shape of the cells, differ from each other in Dunlop and bubbling methods. The attachment of nanoparticles to cell walls and the presence of cavities or cracks in the cell wall were also observed. The density of the foams was also measured and it was found that the foams made by the bubbling method have a lower density than the Dunlop foams. Addition of 6 phr nano alumina to foam made by Dunlop and bubbling method, has increased the tensile strength 41% and 50%, respectively, which shows the greater effect of adding nano-alumina, on the mechanical properties of the foams made by bubbling process. The effect of adding nano-alumina on the vulcanization kinetics, was not significant.
