Polyurethane useful for orthopedics external fixing system in complex environment and preparation method thereof

A polyurethane for an external fixation system for bone surgeries, being a polyether type polyurethane represented by a formula of

• in which, ml representing an integer from 5 to 20, nl representing an integer from 7 to 15 or from 60 to 120, R representing a phenyl group, and
• representing a polyether polyol;
• wherein
• the polyether type polyurethane is prepared by using a polyether polyol mixture and a modified isocyanate as raw materials according to a weight ratio of 1:0.6-0.75;
• (1) the polyether polyol mixture comprises ingredients as follows:
• the polyether polyol
• 60-65 wt. %,
• a catalyst
• 0.3-1 wt. %,
• a foam stabilizer
• 0.1-2 wt. %,
• a foaming agent
• 0.1-2 wt. % or 3-20 wt. %;
• a filler
• 25-40 wt. %;
• and
• a functional additive
• 0.5-2 wt. %;
• the polyether polyol being represented by a formula of
• in which, m is an integer from 7 to 15, R represents mannite, sucrose, or pentaerythritol;
• and
• (2) the modified isocyanate has a formula of
• in which, R represents methyl, benzene ring, a carbamate, or a polyester,
• represents a polyether glycol.