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.