Using twin screw extrusion reaction (TSER) to produce thermoplastic polyurethane (TPU): Tunable, stoichiometric and eco-friendly

TPU and flame-retardant TPU (FR-TPU) were prepared through a polyaddition reaction with polytetramethylene ether glycol (PTMEG) and 4,4′-methylene-bisphenyl-isocyanate (MDI) by reactive extruding. 1,4-Butanediol (BDO) and diethyl bis(2-hydroxyethyl) amino methyl phosphonate (DBAMP) were used as the chain extender in different ratios, respectively, to obtain TPU and flame-retardant TPU (FR-TPU)with adjusted molecular weight and mechanical properties. The resulting TPU and FR-TPU were characterized by FTIR, DSC, TGA, and NMR. A kinetic model based on the data from extrusion process was used to depict the polymerization of TPU. These reactions carried out without any solvent and the residual water showed that the polymerization with BDO could be achieved in 20 minutes, instead, that with DBAMP in 55 minutes while with a similar molecular weight. These results point out that Twin Screw Extrusion Reaction (TSER) is a suitable and convenient way to produce a variety of polymers.