Mark-Houwink Equation Calculator

Calculator Inputs

Calculation Mode

Intrinsic Viscosity [η]

Molecular Weight (M)

Mark-Houwink Constant K

Mark-Houwink Exponent a

Temperature (°C)

Polymer Name

Solvent Name

Sample ID

Notes

Plotly Graph

The graph shows the relationship between molecular weight and intrinsic viscosity for the selected K and a values.

Example Data Table

Sample ID	Polymer	Solvent	Temperature (°C)	K	a	[η]	Estimated M
MH-001	Polystyrene	Toluene	25	0.00021	0.76	1.25	245455.58
MH-002	PMMA	Chloroform	30	0.00011	0.72	0.88	189993.79
MH-003	PEG	Water	25	0.00035	0.65	0.54	62803.16

Formula Used

The Mark-Houwink equation relates intrinsic viscosity and polymer molecular weight through empirical constants:

[η] = K × M^a

To estimate molecular weight from intrinsic viscosity, rearrange the equation:

M = ([η] / K)^1/a

[η] is intrinsic viscosity, M is molecular weight, K is a solvent-polymer-temperature constant, and a describes how coil shape changes with size.

How to Use This Calculator

Choose whether you want molecular weight or intrinsic viscosity.
Enter the known value, along with K and a constants.
Add polymer, solvent, temperature, and sample notes for reporting.
Press the calculate button to display the result above the form.
Review the graph, sensitivity values, and logarithmic outputs.
Export the finished result as CSV or PDF when needed.

Frequently Asked Questions

1. What does the Mark-Houwink equation estimate?

It estimates the relationship between intrinsic viscosity and polymer molecular weight for a specific polymer, solvent, and temperature combination using empirical constants.

2. Why do K and a change between systems?

K and a depend on polymer architecture, solvent quality, and temperature. A constant pair is only valid for the exact experimental system used to derive it.

3. Can this calculator replace direct molecular weight measurement?

It is a practical estimation tool, not a full replacement for direct methods like light scattering or GPC when very high precision is required.

4. What units should I use for intrinsic viscosity?

Use the same intrinsic viscosity units assumed by the published K constant. Unit consistency matters more than the unit name alone.

5. What happens if the a value is small?

A small a value makes molecular weight more sensitive to viscosity changes. Even minor measurement error can cause larger shifts in the estimated molecular weight.

6. Can branched polymers use the same constants?

Not always. Branched polymers often have different hydrodynamic behavior, so constants derived for linear chains may give misleading results.

7. Why are temperature and solvent fields included?

They document experimental conditions. Mark-Houwink constants are condition-specific, so recording them improves traceability and report quality.

8. Does the graph use my entered constants?

Yes. The plotted curve is generated from your selected K and a values, centered around the current calculation result.