Liquid crystalline polymers under shear
- Univ. of Cambridge (United Kingdom)
The rheological behaviour of main-chain thermotropic liquid crystalline polymers (LCPs) have been studied extensively as a result of their versatility as moulding compounds. In-situ microscopic observations of complex fluids under shear has proved to be a very convenient technique because such methods are an ideal tool to establish the connection between rheology, morphology and microstructure of polymeric materials under controlled shear and thermal histories. The present study focuses on an in-situ WAXS study on main-chain aromatic thermotropic copolyesters, subjected to steady-shear flow. In order to gain more insight in the underlying mechanisms of flow, several parameters are varied. They include shear rate, temperature and molecular mass. We find different flow behaviour in thermotropic random copolyesters. Depending on the strain rate, temperature and molecular mass the molecular director will display orientation either orthogonal (log-rolling) or parallel (flow-aligning) to the flow direction. It is believed that regions of local register between chain sequences present in the melt phase, and therefore, forming smectic-like entities, is the factor which stabilises the log-rolling mode.
- OSTI ID:
- 370876
- Report Number(s):
- CONF-960376--
- Country of Publication:
- United States
- Language:
- English
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