THE DEFORMATION AND BREAK-UP OF THERMOTROPIC CO-POLYESTER DROPLETS INA MOLTEN POLYPROPYLENE MATRIX SUBJECTING TO OSCILLATORY SIMPLE SHEAR AND ENTRY FLOW

In this paper, we report experimental optical observations on the defo rmation, possible breakup and coalescence of molten thermotropic liqui d crystalline polymers (TLCPs) embedded in a molten polypropylene matr ix. Both simple oscillatory shear and extensional flow deformations ar e considered. In the case of oscillatory simple shear, different regim es of deformation and filament formation are observed. In one case, st able filaments form by an accumulated strain effect. In the second cas e, extended unstable filaments are formed mainly by filament coalescen ce. It is found that the coalescence of droplets occurs by droplets mi grating towards each other. The low pressure produced behind the dropl ets during flow was thought to be the driving force for the droplets a lignment and migration. Experiments on droplets deformation and relaxa tion in extensional entry flow experiments are also presented, and fro m the data presented in the paper it is possible to establish general conditions for the formation and survival of TLCP filaments in a therm oplastics matrix, which is a necessary condition for the manufacture o f in situ self reinforced thermoplastic products. (C) 1999 Elsevier Sc ience B.V. All rights reserved.