화학공학소재연구정보센터
Journal of Applied Polymer Science, Vol.104, No.4, 2212-2218, 2007
Shear rate dependence of viscosity and first normal stress difference of LCP/PET blends at solid and molten states of LCP
The liquid crystalline polymer (LCP) and polyethylene terephthalate (PET) were blended in an elastic melt extruder to make samples having 20, 40, 60, 80, and 100 wt % of LCP. Morphology of these samples was studied using scanning electron microscopy. The steady state shear viscosity (eta), dynamic complex viscosity (eta*) and first normal stress difference (NI) were evaluated and compared at two temperatures: 265 degrees C, at which LCP was in solid state, and 285 degrees C, at which LCP was in molten state. The PET was in molten state at both the temperatures. The shear viscosity of the studied blends displayed its dependence on composition and shear rate. A maxima was observed in viscosity versus composition plot corresponding to 80/20 LCP/PET blend. The N-1 increased with LCP loading in PET and with the increased asymmetry of LCP droplets. The N-1 also varied with the shear stress in two stages; the first stage demonstrated elastic deformation, whereas second stage displayed dominant plastic deformation of LCP droplets. (c) 2007 Wiley Periodicals, Inc.