Rigid liquid-crystalline networks physics

Rusakov 107 108) recently proposed a simple model of a nematic network in which the chains between crosslinks are approximated by persistent threads. Orientional intermolecular interactions are taken into account using the mean field approximation and the deformation behaviour of the network is described in terms of the Gaussian statistical theory of rubber elasticity. Making use of the methods of statistical physics, the stress-strain equations of the network with its macroscopic orientation are obtained. The theory predicts a number of effects which should accompany deformation of nematic networks such as the temperature-induced orientational phase transitions. The transition is affected by the intermolecular interaction, the rigidity of macromolecules and the degree of crosslinking of the network. The transition into the liquid crystalline state is accompanied by appearence of internal stresses at constant strain or spontaneous elongation at constant force. 

Liquid crystalline thermosets (LCT) with a rigid rod-like mesogenic group capped firom both ends by reactive fimctional groups can be used as matrices for production of advanced composites, coatings or adhesives (1, 2). hi this case ordering of the chains of the final network polymer is the only way to improve its physical and mechanical properties. 

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