Synthesis and Properties of Polyurethane Foams Obtained from Cassava Starch and Rice by-products

The Huila department (Colombia) has a continuous growth in the production of rice, being the second largest national producer with increased production of rice in the central part of the country with yields of 6.8 T/Ha in the first half of 2014, resulting in a large accumulation of waste and inadequate use and management of water resources. The by-products generated in the post-harvest, such as chaff, straw and rice husks, end up being used as fuel with no additional advantage. In this work there were prepared and characterized polyurethane foams obtained by cassava starch and rice biomass mixture. Polyurethane foams are commercially used in horticulture and agriculture, which becomes an alternative solution for the use of biomass. The use of the byproducts of rice in the preparation of polyurethane foams in horticulture and agriculture purposes is proposed here. The polurethane foams were obtained from mixtures of cassava starch, rice biomass previously treated with 0.1N NaOH, and commercial methylene diphenyl diisocyanate and polyol. The endpoint was the cassava starch and rice biomass wt.% used in the mix. Density, water absorption and hardness of polyurethane foams were determined, and they were characterized by infrared spectroscopy and scanning electron microscopy. 33-44x10(-3) g/cm(3) y 26-46 x10(-3) g/cm(3) were the values of densities obtained for cassava starch- and cassava starch and rice biomass-based polyurethane foams, respectively, and they reached a value of water absorption until 353.0 %. Infrared spectra confirmed the N-H functional groups (3301 cm(-1)) and CO (1309 cm(-1)) characteristic of the polymer. The cassava starch- and cassava starch and rice biomass-based polyurethane foams got smaller pores (114.4 mu m) and (132-580 mu m), respectively, compared to pores obtained from commercial foams (1092 mu m).