Wheat straw-derived bio-based hydroponic polyurethane foams for plant growth

Agricultural waste is a renewable and sustainable resource that can be used as an alternative to petroleum for the production of chemicals and materials. In this study, liquefied wheat straw was used as bio-polyols to prepare bio-based hydroponic polyurethane (BHPU) foams. The effects of foam preparation variables, such as surfactants, catalysts, blowing agents and types of petroleum-based polyols (PPG 400 and/or VORANOL 280) on the properties of BHPU foam were investigated through single-factor experiments. Response surface methodology was applied to optimize the foam formula. The prepared BHPU foams with 40-50% (w/w) bio-polyols had an open cell content of 70-96%, a water absorption capacity of 594-1085% (w/w) and a water absorption time of 6-140 s. The potential of using the prepared BHPU foam as a plant growing medium was evaluated via mechanical testing, cell morphology, thermal stability, UV weathering testing and Phaseolus vulgaris (Linn.) cultivar Prelude and Glycine max (Linn.) Merr. seed germination tests. The wheat straw-derived BHPU foams demonstrated potential as a plant growth medium in horticulture. (c) 2022 Society of Chemical Industry and John Wiley & Sons, Ltd.