POLYMERS FROM RENEWABLE SOURCES .5. MYRCENE-BASED POLYOLS AS RUBBER-TOUGHENING AGENTS IN GLASSY POLYURETHANES

A reactive liquid rubber based on hydroxy-funcionalized polymyrcene was used to modify a highly-crosslinked, glassy polyurethane network. During the polymerization, the products formed from the reacting liquid rubber and the polyurethane matrix components become incompatible leading to precipitation of the rubber as a discrete particulate phase. Phase-separation in the resultant rubber-modified polyurethanes is essentially complete, and the materials possess improved stress-strain and impact properties relative to the unmodified network, without reduction of the glass transition temperature (155 degree C) of the network. The mechanisms of energy dissipation accounting for the toughness changes are reviewed and compared with those observed in epoxy resins modified by polybutadiene-based liquid rubbers.