Temperature Dependence Of Liquid Viscosity Article Index for
Temperature 		Website Links For
Temperature 		 

Information About

Temperature Dependence Of Liquid Viscosity
  CATEGORIES ABOUT TEMPERATURE DEPENDENCE OF LIQUID VISCOSITY
   
non-newtonian fluids
   
APPAREL
BABY
BEAUTY
BOOKS
CAR TOYS
CELL PHONES
DVD'S
ELECTRONICS
GOURMET FOOD
GROCERIES
HEALTH & PERSONAL
HOME & GARDEN
JEWELRY
MUSIC
MUSIC INSTRUMENTS
OFFICE PRODUCTS
SOFTWARE
SPORTING GOODS
TOOLS & HARDWARE
TOYS
VIDEO GAMES
SHOPPING HOME
MORE SHOPPING...




EXPONENTIAL MODEL


:\mu(T)=\mu_0 \exp(-bT)

where ''T'' is temperature and \mu_0 and b are coefficients. See First-order Fluid and Second-order Fluid .
This is an Empirical Model that usually works for a limited range of temperatures.


ARRHENIUS MODEL


The model is based on the assumption that the fluid flow obeys the Arrhenius Equation for Molecular Kinetics :

:\mu(T)=\mu_0 \exp( rac {E}{RT} )

where ''T'' is temperature, \mu_0 is a coefficient, ''E'' is the Activation Energy and ''R'' is the Universal Gas Constant .
A first-order fluid is another name for a power-law fluid with exponential dependence of viscosity on temperature.


WLF MODEL


The Williams-Landel-Ferry model or '''WLF''' for short is usually used for Polymer Melt 's or other fluids that have a Glass Transition Temperature .

The model is:

:\mu(T)=\mu_0 \exp \left( rac {C_1 (T-T_r)} {C_2+ T -T_r )} ight)

where ''T''-temperature, C_1, C_2, T_r and \mu_0 are empiric parameters (only three of them are independent from each other).

If one selects the parameter T_r based on the glass transition temperature, then the parameters C_1, C_2 become very similar for the wide class of Polymer s. Typically, if T_r is set to match the glass transition temperature T_g, we get

:C_1 \approx17.44

and

:C_2 \approx51.6 K.

Van Krevelen recommends to choose

:T_r=T_g+43 K, then

:C_1 \approx8.86

and

:C_2 \approx101.6 K.

Using such ''universal parameters'' allows one to guess the temperature dependence of a polymer by knowing the viscosity at a single temperature.

In reality the ''universal parameters'' are not that universal, and it is much better to fit the WLF parameters from the experimental data.