The Synthesis and the Bulk Rheological Properties of the Highly-Branched Block Polyethers

Several kinds of highly-branched block polyethers were synthesized via anion ring-opening polymerization of propylene oxide (PO) and ethylene oxide (EO), using phenol-amine resin (PA) as the initiator. The rheological properties determined by rotational rheometer all followed the regular rules of polymer systems: under a certain conditions, the bulk polyethers were pseudoplastic and non-Newtonian fluid, and with the increasing of the shear rate and temperature, the apparent viscosity of the block copolymers were reduced. In addition, modulus determination showed that such polyether molecules presented preferable viscosity compared to the elasticity, meanwhile, storage modulus, loss modulus and compound viscosity all decreased with the increasing of temperature. Storage modulus and loss modulus increased along with the scanning frequency increasing. But compared with the same kind of linear polymers, the significant difference was the low melt viscosity, which attributed to the special three-dimension space structure hindering the entanglement of chains. Furthermore, the rheological properties among the several block polyethers showed differences obviously. In other words, the number of block and the content of EO all have a significant effect on the rheological properties, specifically, the modulus will increase with the increasing of the block number and the EO content.