What Is the Williams-Landel-Ferry (WLF) Shift Factor Calculator?
The WLF equation relates polymer relaxation rate acceleration with temperature above Tg.
How Does the Williams-Landel-Ferry (WLF) Shift Factor Calculator Work?
Free volume expansion above Tg allows molecular segments to move faster, shifting relaxation spectra to higher frequencies.
Williams-Landel-Ferry (WLF) Shift Factor Calculator Formula & Variables
The core mathematical equation utilized by this calculator is expressed as:
\log_{10}(a_T) = \frac{-C_1 (T - T_g)}{C_2 + (T - T_g)}
WLF empirical equation for time-temperature superposition shift factor.
How to Use the Williams-Landel-Ferry (WLF) Shift Factor Calculator
- Enter operating temperature, glass transition temperature, and C1/C2 constants.
Step-by-Step Example Calculation
Polystyrene Superposition
Input Values:
temperatureCelsius:120
glassTransitionTempCelsius:100
c1Constant:17.44
c2Constant:51.6
Worked Steps: Calculates log10(aT) ~ -4.87 for T - Tg = 20 K.
Understanding Your Result
Outputs log10(aT) and shift factor multiplier aT.
Factors That Affect the Result
- Temperatures close to Tg produce dramatic logarithmic changes in relaxation times.
When Should You Use This Calculator?
- Constructing master curves for storage/loss moduli and predicting 50-year polymer service life from short-term tests.
Assumptions & Limitations
- Valid strictly in the range Tg < T < Tg + 100 °C; Arrhenius behavior dominates at higher temperatures.
Frequently Asked Questions
Calculation Accuracy & Reference Note
Universal constants C1 = 17.44 and C2 = 51.6 K provide accurate baselines for most amorphous polymers.