effect of clay modifier on the structure and transport properties in polyurethane/clay nanocomposites as barrier materials

In this study, nanocomposites of thermoplastic polyurethane (tpu) clay are synthesized and used as a gas barrier property. the nco-terminated tpu prepolymer was prepared by solution polymerization method using a 1:2 ratio of polyethylene glycol (peg2000) and tolylene 2,4-diisocyanate (tpi). organo-modified montmorillonite clay, cloisite 25a(c25a) was used as ample compatibilization with peg/tpi matrix. the prepared nanocomposite was characterized by fourier transform infrared (ft-ir) spectroscopy, x-ray diffraction (xrd), scanning electron microscope (sem), and thermogravimetric analysis (tga). the main functional group peaks of the nanocomposite materials are observed in ft-ir spectroscopy. the nanocomposites exhibited better thermal stabilities than pristine polyurethane which is investigated by tga. thermal stability in the sample with 5 wt.% of tpu/c25a-5 material has improved up to 70ºc. the xrd results have confirmed the penetration of clay into tpu matrix, with the disappearance of the characteristic peak (2θ = 4.81º) corresponding to the d-spacing of the organoclay. sem analysis confirmed the dispersion of nanoclay in tpu matrix. the mechanical properties of nanocomposites such as the tensile strength and young's modulus of tpu/cl25a nanocomposites were increased with increasing clay percentage. the gas permeability test was studied using a membrane separation testing unit. significant improvements in barrier properties were observed. a remarkable decrease was seen in polyurethane incorporated with 5 wt.% organoclay when tested with oxygen and nitrogen gas.