ABSTRACT:To know the possibility of using Indian butter tree seed waste (mahua seed cake [MSC]) as a filler in the production of value-added product such as polyurethane (PU) green composites, a series of PU composites have been fabricated with varying amounts, namely, 0, 2.5, 5.0, 7.5, and 10 wt%, of MSC, and their effects on the physicomechanical properties such as density, surface hardness, tensile strength, tensile modulus, and percentage elongation at break have been studied. It was found that the tensile strength of the green composites increased from 5.61 to 9.5 MPa and tensile modulus increased from 4.75 to 6.07 MPa with an increase in filler content from 2.5 to 7.5 wt%. The fabricated PU/MSC composites were characterized for structural behavior by Fourier transform infrared spectroscopy and for morphological behaviors by scanning electron microscopy. The chemical resistance of the green composites in different chemical environments has been investigated. The thermal stability and thermal degradation behaviors of composites were performed using thermogravimetric analysis. The microcrystalline parameters such as crystallite size () and lattice strain (g, %) have been computed using wide-angle X-ray scattering data. Based on these parameters, the structure-property relationship of the PU/MSC green composites has been established. C 2015 Wiley Periodicals, Inc. Adv Polym Technol 2015, 0, 21598; View this article online at wileyonlinelibrary.com.