Nanoparticle effects of thermoplastic polyurethane on kinetics of microphase separation, with or without preshear

The present research was carried out in two stages. First, various nanoparticles (Closite30B and multiwalled carbon nanotubes [MWCNTs]) for reinforcement of the polymer matrix were prepared and characterized. Samples were prepared with a melt mixing technique. In the next step, the kinetics of phase separation of thermoplastic polyurethane with nanoparticle (Closite30B, MWCNTs) and preshear were investigated by linear viscoelastic experiments, including frequency sweep and time sweep tests, which were performed on TPU/Closite30B/MWCNT samples varying in nanoparticle content at rheological measurements. The kinetics of phase separation at high preshear and a lower percentage of nanoparticles increased, while they showed a decrease in higher compositions. The nucleation effect of nanoparticles and the effect of preshear with the orientation of the hard segment increases the kinetics of phase separation of the soft and hard segments. The differential scanning calorimetry (DSC) showed that multiple endothermic peaks of thermoplastic polyurethane were affected in the presence of nanoparticles. Dynamic mechanical tests showed that Closite30B has greater affinity with the soft segment and MWCNTs with the hard segment, according to the DSC and rheological experiments. Finally, it was observed that the shear flow and nanoparticles can accelerate phase separation kinetics, but the effect of preshear on the kinetics of phase separation was reduced in the presence of a strong nucleating agent like MWCNTs. POLYM. COMPOS., 39:4551–4559, 2018.