Non-Newtonian Melt Flow

The only parameter included is the shear rate 7. There is an instrument which is widely used because it realizes simple shear flow conditions in a manner convenient for experiments. This is the cone-and-plate rheometer sketched on the left-hand side of Fig. 7.14. The polymer melt is placed in the gap and, if the gap angle is kept small, then the shear rate is the same everywhere. With the aid of this apparatus, various experiments may be carried out, as for example 

The two material parameters which characterize polymeric fluids at low strain rates, the viscosity, j, and the recoverable shear compliance, Je, can be directly determined, rj follows from the measurement of the torque under steady state conditions, Jq shows up in the reverse angular displacement subsequent to an unloading, caused by the retraction of the melt. From the discussion of the properties of rubbers we know already that simple shear is associated with the building-up of normal stresses. More specifically, one finds a non-vanishing 

The process thus differs from a drawing where clamps attached to the two 

The constant in Eq. (7.113) is known as the Hencky rate of extension and we choose for it the symbol en 

Whereas experiments conducted with a constant rate of elongation yield a linear extension with time, those carried out with a constant Hencky rate result in an exponential time dependence of A 

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Figure 3.1 Non-plastic (Newtonian) and plastic (non-Newtonian) melt flow behavior (courtesy of Plastics FALLO)...

Thermoplastics have non-Newtonian melt flow characteristics it means that their viscosity will change dependent on their velocity or the amount of shear that occurs in the melt (Chapter 1). This non-Newtonian characteristic is a key in thin wall molding. As in any molding setup one cannot just simply ram the melt into the cavity. It s flow characteristic, gate size as well as position, and venting have to be balanced in order to obtain the desired structural part and meet tight tolerance requirements. 

Version 1 (1989) Isothermal, non-Newtonian melt flow Wang et al. [158]... 

Version 2 (1993) Non-isothermal, non-Newtonian melt flow Chen and White [159]... 

Non-Newtonian melt flow with melting Potente et aL [152]... 

Non-Newtonian Melt Flow and for the primary normal stress difference... 

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