TWI Frequently asked questions
by Sam Rostami
The liquid crystal phase in LCPs can be uniaxially or biaxially oriented under a shear flow. As a result, the rigid liquid crystal phase is aligned in the direction of the flow to act as a self-reinforcing agent. For this reason,the LCPs are also called self-reinforcing polymers, SRPs. A liquid crystal polymer is, therefore, significantly mechanically stronger in the orientation direction than in transverse direction.
Due to the close molecular packing of the liquid crystal regions, the LCPs have high barrier to transport of water vapour and gas molecules. For the same reason, they show a strong resistance to chemical attack.
During an extrusion and moulding operation, the liquid crystal regions align themselves under the applied shear flow. This causes a significant reduction in the shear viscosity of LCPs that allows complex mouldings, such as mouldedcircuit boards, to be made from LCPs. As thixotropic materials, they can be used as a viscosity modifier in processing of high viscosity thermoplastic polymers.
The liquid crystal regions, however, show poor ability to mix with other phases, which can result in weak weld lines in moulded parts. LCPs are generally incompatible with other polymers.
Further information
What are liquid crystal polymers (LCPs)?
How are liquid crystal polymers (LCPs) made?
What are the applications of liquid crystal polymers (LCPs)?
