The deformation and break-up of thermotropic co-polyester droplets in a molten polypropylene matrix subjecting to oscillatory simple shear and entry flow
Mackley, Malcolm R.
|Source||Journal of non-Newtonian fluid mechanics , v. 80, (2-3), 1999, JAN, p. 199-216|
|Summary||In this paper, we report experimental optical observations on the deformation, possible breakup and coalescence of molten thermotropic liquid crystalline polymers (TLCPs) embedded in a molten polypropylene matrix. Both simple oscillatory shear and extensional flow deformations are considered. In the case of oscillatory simple shear, different regimes of deformation and filament formation are observed. In one case, stable filaments form by an accumulated strain effect. In the second case, extended unstable filaments are formed mainly by filament coalescence. It is found that the coalescence of droplets occurs by droplets migrating towards each other. The low pressure produced behind the droplets during flow was thought to be the driving force for the droplets alignment and migration. Experiments on droplets deformation and relaxation in extensional entry flow experiments are also presented, and from the data presented in the paper it is possible to establish general conditions for the formation and survival of TLCP filaments in a thermoplastics matrix, which is a necessary condition for the manufacture of in situ self reinforced thermoplastic products. (C) 1999 Elsevier Science B.V. All rights reserved.|
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