proceedings article

Abstract

Two crystallisation processes exist in HBA/HNA copolyesters, such as Vectra A900: a fast and a slow one. The slow crystallisation process is responsible for the phenomenon of recrystallization, which is observed in slow flows just above the nominal melting crystalline / liquid crystalline transition. Then the melt of Vectra A900 is not stable and residual crystallites with a higher melting point start to grow further within the nematic melt. This causes the viscosity to increase and the melt may eventually resolidify. The recrystallization is one of the major causes of the great variance in the reported rheological behaviour of Vectra A900. It is also shown in this report that the degree of the recrystallization depends on the accumulated strain during the slow flow.

Proceedings of the 12th. PPS meeting, p. 8.13, 1996

The influence of crystallisation on the rheological behaviour of HBA/HNA copolymers