Rheological properties of thermotropic liquid crystalline polymers

RHEOLOGICAL PROPERTIES OF THERMOTROPIC LIQUID CRYSTALLINE POLYMERS 

When compared with conventional melts, the LCP melts show a number of other characteristic deviations  

Cogswell (1985) expressed it in the following words To make the connection from the basic material properties to the performance in the final product, industrial technologists had to learn a new science . It is more or less so, that - for liquid crystal polymers -properties like stress history, optical and mechanical anisotropy, and texture seem to be independent variables this in contradistinction to the situation with conventional polymers. 

42 Schematic representation of the viscosity (A) as a function of temperature for thermotropic LCPs and (B) as a function of concentration for lytropic LCPs. 

Liquid crystal polymers have a potentially low viscosity, but that potential becomes only manifest when the system is flowing. Since they have a yield stress, LCP melts cannot be assumed to have a low viscosity at rest. 

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The shear rheological properties of thermotropic liquid crystalline polymers (TLCPs) have been studied extensively whereas, the extensional behaviour of TLCPs has become the subject of very few studies (Gotsis and Odriozola 2000). The unusual orientation and structure of thermotropic liquid crystal polymers (TLCPs) can significantly affect the rheological and mechanical properties of... 

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