Synthesis and characterization of organically modified clay/castor oil based chain extended polyurethane nanocomposites

A series of 1,4-butane diol chain extended polyurethane nanocomposites based on castor oil, and 4,4′-diphenylmethane diisocyanate (MDI) were synthesized with modified clay (Cloisite 30B) as filler. The synthesis was carried out in bulk and without catalyst via a two-step polymerization. The clay percentage was varied from 0% to 5% by weight of the nanocomposite. The prepared nanocomposites were characterized using TEM, SEM, WAXD, FTIR, Thermogravimetric Analysis (TGA), mechanical properties and Moisture absorption behavior. TEM and XRD results confirmed successful exfoliation of clay in the polyurethane matrix. Thermogravimetric Analysis (TGA) results showed that the thermal stability of nanocomposites improved with increased percentage of clay. Moreover, char percent also increased from 5.6% to 12% as clay percent increased from 0% to 5%. The Young’s modulus improved more than 300% with addition of 5% clay filler. These nanocomposites exhibited lower water absorption and diffusivity values as compared to neat polyurethane.