Dynamic Mechanical and Thermal Properties of Polyurethane Block Copolymers Based on the Tetramethyl Xylene Diisocyanate Group.

摘要

A series of polyurethane model compounds based on the meta and para isomers of tetramethyl xylene diisocyanate have been prepared. The compositional parameters varied in these urethanes included: the isocyanate content, the cure stoichiometry, and the nature of the soft segment. These urethanes contained soft segments based either on non-polar hydroxy-terminated polybutadiene or the highly polar-polycaprolactone. Changing the isocyanate content of these polyurethanes was found to significantly affect their dynamic mechanical properties. In addition, urethanes of the same isocyanate content are found to have large differences in their dynamic mechanical behavior depending on whether the meta or para isomer of tetramethyl xylene diisocyanate is used in their formation. A low-temperature glass transition attributed to the soft segment was observed in all of these urethanes by Differential Scanning Calorimetry. Changes in the position of this glass transition can be correlated to the dynamic mechanical results.