Polymer Bulletin, Vol.32, No.5-6, 669-674, 1994
Thermal and Dynamic-Mechanical Properties of New Chiral Smectic Networks
The thermal and dynamic-mechanical behavior of two chiral liquid-crystalline networks are described. Both polymer networks formed a smectic mesophase whose isotropization temperature and enthalpy decreased with increasing crosslinking degree. The dynamic-mechanical behavior was studied in the linear viscoelasticity range. Three main relaxation regions were assigned to the beta relaxation, the a network relaxation and the isotropization. Thus, it was possible to monitor the dynamic-mechanical response of the networks in both the anisotropic and isotropic states. Values of the storage and loss dynamic moduli in the range 10(6)-10(7) Pa were detected in the isotropic state. Above the a relaxation temperature, either an elasticity or viscosity dominant state was observed depending upon the crosslink density of the network.
Keywords:LIQUID-CRYSTALLINE ELASTOMERS;C-STAR-PHASES;CHOLESTERIC ELASTOMERS;PIEZOELECTRICITY;POLYMERS;PHOTOPOLYMERIZATION;MOLECULES;BEHAVIOR