Isocyanate modification of rice husk for using in polyurethane foam composite

The hard polyurethane foams are one of the most consumed polymer foams as thermal insulation. Excessive consumption of these materials and their non-biodegradability is one of the human concerns in the field of environmental considerations. There are different ways to improve the biodegradability of polymers. The use of natural biodegradable materials in the polymer matrix is one of the solutions. Here, for the first time, rice husk, which is one of the abundant agricultural wastes in the country, has been used in polyurethane insulation foams. First, the rice husks were ground and sieved. Then, these materials were divided into two groups. One group of these materials was subjected to alkaline treatment. Both alkaline and non-alkaline treatment groups were subjected to isocyanate modification. For isocyanate modification, 20% by weight of isocyanate compounds were used. Both alkaline treat mentation and isocyanate modification methods were investigated using an infrared spectroscopy test. Then, the modified rice husks were added to the polyurethane foams at a rate of 5% by weight. Finally, the mechanical and insulating properties of the foams were evaluated. The results showed that both groups of isocyanate-modified rice husks, non-alkaline treatment, and alkaline treatment improved the compression strength properties of the polyurethane foams up to 89%. Also, the insulation properties of the foams are improved, too. improved, too.