| abstract |
A crosslinked polymer for use in an orthodontic appliance, the crosslinked polymer has a tensile modulus of 800 MPa to 2000 MPa, a tensile strength at yield strength of 20 MPa to 55 MPa, an elongation at yield strength greater than 4% and an elongation at break greater than 30%, as measured by the procedure disclosed in the description; wherein the crosslinked polymer comprises a first repeating unit derived from a urethane (meth) acrylate oligomer and a second repeating unit derived from a vinyl or thiol monomer in which at least one of the (meth) acrylate oligomer is urethane, the vinyl monomer and the thiol monomer comprise at least two polymerizable groups. |