| 초록 |
Thermoplastic polyurethane (TPU) is one of versatile thermoplastic elastomers. In our work, a series of TPU, in which hard segment lengths were systematically changed, were prepared by solution polymerization technique in N, N-dimethyl formamide (DMF). The properties of TPU solution in DMF were then investigated for both dilute and concentrated solutions by means of Ubbelodh viscometer and cone-plate rheogoniometer. Enormous increase of complex viscosities and storage moduli of TPU solutions were observed with increasing the hard segment length of TPU. Intrinsic viscosity as well as second virial coefficient (A2) of TPU solution also increased with increasing hard segment length. These phenomena imply the increase of hydrodynamic volume of TPU molecules in solutions and intermolecular entanglements in concentrated solutions of TPU containing longer hard segments. |
