Characterization of polyester type hyperbranched polyurethane

Hyperbranched polyurethane (HPBU) was synthesized by the method of "arm first and core later". The FT-IR and GPC were used to characterize the structure of HBPU. The results showed that the reaction happened as expected routine. Compared with common liner polyurethane, the Mn of HBPU increased 22% and Mw increased 37% at the same viscosity, which demonstrated that HBPU had advantage in low viscosity and easy flowing. The spectrum of X-ray shows the crystallinity of HBPU is higher than the PU, so the cell arranged of the HBPU is more regular.