Preparation and characterization of biodegradable flexible polyurethane foam containing acetylated tapioca starch and Castor oil

This research project focused on developing flexible polyurethane foams with high biodegradability, suitable as substrates for growing vegetables or cereal sprouts. These foams incorporated acetylated tapioca starch as a filler and castor oil, and their properties were evaluated. Experiments assessed how varying concentrations of acetylated starch (0, 15, 30, 45, and 60 wt%) and castor oil (0, 10, 20, and 30 wt%) affected the foams' density, tensile properties, compression set, moisture absorption, biodegradability, and microstructure. Results indicated that increasing acetylated starch concentration led to higher density, compression set, biodegradability, and closed cell percentage, while tensile strength, elongation at break, water absorption, and mean cell diameter decreased. Most changes were significant (p < 0.05), with density, compression set, biodegradability, tensile strength, elongation at break, water absorption, and average cell diameter being 21.7 kg/m², 11.4%, 9.2%, 101.4 kPa, 97.2%, 3820%, and 0.34 mm respectively, for foam without castor oil and acetylated starch compared to 33.1 kg/m², 19.7%, 37.7%, 62.3 kPa, 28.9%, 2600%, and 0.186 mm for foam with 60 wt% acetylated starch, respectively. The influence of castor oil concentration on the foams' physical and mechanical properties was inconsistent. Additionally, the germination amount of grown green basil seeds on commercial flexible polyurethane foam was higher than that of selected prepared foam (84.7% vs. 81.3%), but the germination rate of grown green basil seeds on selected prepared foam was higher than that of commercial foam at all times, including the ninth day (4.7 vs. 4.2 cm).