Rotational blow molding of thermotropic liquid crystal polymers and resulting orientational structure and mechanical properties

Liquid crystal polymers(LCP)is one of the most promising choices of 5G antenna material in the future, but its rigid rod-like macromolecular chain and the lack of melt elasticity make it difficult to produce film. In this paper, LCP film is successfully prepared based on a blow molding device developed in-house which the mandrel rotates in reverse with the outer die and the effect of annular shear on the orientation structure and mechanical properties of LCP film is investigated. SEM graphics show that obvious self-reinforcing fibers and the fiber cross structure are formed in the LCP film under the synergistic effect of annular shear flow field and axial extrusion. Polarization infrared pole diagram and 2D-WAXD results prove that the orientation degree of LCP film tends to be uniform with the increase of rotational speed. The tensile results show that the die rotation greatly reduces the gap between the longitudinal and transverse mechanical properties of the film, and even the transverse properties exceed the longitudinal properties at the rotational speed of 55 rpm. The LCP film with uniform mechanical properties is obtained eventually.