Rigid-Rod Networks Liquid-Crystalline Epoxy-Resins

Liquid crystalline polymers are well known for their unique mechanical and theological properties. In recent years, some interest has been devoted to the study of a new class of liquid crystalline thermoset based on epoxy resins. Liquid crystalline epoxy resins can be obtained either by curing glycidyl terminated prepolymers over a range of temperature in which the mesophase is stable, or by reacting epoxy functionalized rigid monomers with a suitable curing agent. In our work this second approach has been followed. An unusual behaviour has been found for the form of the exotherm during increased curing temperature. Fracture toughness K-q, was found to decrease with increased curing temperature. This experimental evidence has been correlated with the reduction of the extent of liquid crystalline character with temperature.