CONICET | Buscador de Institutos y Recursos Humanos

A current need of the polyurethane industry is to identify new sources of reagents for polymer synthesis to replace petrochemical raw materials by those obtained from renewable sources. In this work, a chemically modified tung oil was used as the main polyol component in the formulation of viscoelastic (low resilience) polyurethane foams. Rice Husk Ash (RHA), a residue from the rice process industry, was chosen to be incorporated as rigid filler in these materials because of its high silica content. Water was used as blowing agent in order to increase the green nature of the reinforced foams. RHA addition leads to noticeable changes in several properties, mainly thermal conductivity, density and foam morphology, even at the low filler content used in this work. Reinforced foams presented larger characteristics times than the neat one, which was considered as an advantage, since filler addition increases the viscosity of the liquid reactive mixture and, therefore, more time is required for an adequate homogenization. FTIR analysis showed the typical bands expected for polyurethane foams while SEM images revealed a mainly closed cell structure for both the unfilled and filled samples. Although the thermal stability was almost unaffected by ash content, a stabilizing effect of the inorganic filler was identified, since the residual char was higher than predicted from theoretical calculations. The reinforced foams showed higher thermal conductivity than that of the unfilled samples, even though the increase was within 20% and they still behave well in the range of polyurethane foams for applications in the construction industry. Summarizing, the tung oil based polyol revealed itself as a good alternative to replace petrochemical raw materials for polyurethane production. In particular, these tung oil derived foams can be used as substitute of petroleum derived formulations in semi-structural applications where low weight and insulating properties are desirable.