Time dependent rheological behaviour of liquid crystal polymers (LCPs)

The rheological properties of side chain thermotropic liquid crystalline polymers (TLCPs) have been observed as a function of time at constant temperature. Under constant shear rate, the molecules tend to align in the direction of the flow as well as tumble along their own axis. Viscosities, elastic and viscous moduli increase with time at constant frequency and temperature. The abnormal orientation and architecture of LCP molecules leads to continually increasing crystalline phase of LCP molecules at constant shear rate and temperature. The time dependent behaviour is pronounced at low shear rate. But the high shear opposes the recrystallization in LCPs. The time dependent rheological properties are observed by the dynamic time sweep test. There is no remarkable change over a time scale of approximately 10 minutes.