Effect of Two Different Series of Nanoclays on the Thermal and Mechanical Properties of Thermoplastic Polyurethane-clay Nanocomposites

In this study, Polyurethane-clay nanocomposites were prepared via in situ polymerization method. Polyurethane matrix was synthesized by reaction between 2, 4 Toluene Di-isocyanate (TDI), poly caprolactone (PCL) with commercial name of CAPA 240 and 1,4-Butanediol as chain extender. In nanocomposites preparation, the nanoclays of Cloisite® 15A, Cloisite® 20A, Cloisite® Na+, DELLITE® 67G, DELLITE® 43B, DELLITE® 72T, DELLITE® LVF, and DELLITE® HPS were used as reinforcement phase (1%wt). In order to study morphology of nanocomposites, Transition Electron Microscopy (TEM) and X-ray Diffraction analysis were applied. The results showed the exfoliated morphology in nanocomposites containing 30B and 43B while, in 67G, 15A, 72T and 20A containing nanocomposites intercalation behavior were seen. Also partialy intercalation/agglomeration behavior was observed among Na+, LVF and HPS clays. This diversity in behavior was originated from difference in type and amount of used modifiers.In addition, mechanical and thermal properties of considered nanocomposites were investigated using Differential Scanning Calorimetry (DSC), Thermal Geravimetry analysis (TGA) and Universal Testing Machine. The results revealed that adding small amounts of nanoclays as modifier to polyurethane matrix led to increase in some properties such as glass transition temperature (Tg), melting temperature(Tm), degradation temperature and elastic modulus.In this study among mentioned nanoclays, 30B and 43B played remarkable role in modification of final polymer properties.. Among other nanoclays; 72T, 20A, 67G and 15A can be named respectively to have superior improvement effect on matrix properties. These nanoclays exhibited same influences because of their similar modifiers.Due to unsuitable dispersion in polymer matrix, some nanoclays not only showed no modification effect but also caused degradation of such properties in experiments.

Keywords:

polyurethane , nanoclay , TPU , nanocomposite , thermal properties