High modulus liquid crystalline thermosetting resins through novel processing techniques

摘要

The authors have demonstrated the effects of magnetic field alignment for the epoxy resin system, the diglycidyl ether of dihydroxy-(alpha)-methylstilbene cured with sulfanilamide. With increasing magnetic field, the tensile modulus of the thermoset can be enhanced by a factor of three, without compromise to the transverse value. Measurements of the coefficients of thermal expansion and the order parameter as determined by x-ray diffraction elucidate the high degree of alignment obtained at field strengths of 15--18 Tesla. The interrelationship between the reaction kinetics of curing with the molecular alignment process is central to successful processing of this class of thermosets. Preliminary relationships between the field strength, time in the magnetic field, reaction rate, and extent of reaction have been developed. Process control and sequencing allow a wide adjustment in the properties of the produced samples. These studies demonstrate the increased value of multi-mode processing in the development of tailored property, lightweight materials.