evaluate material property in matlab livelink

Dear comsolers,

How can I get a value of material property in matlab livelink?

For example, material like 'air' is added from the material library.

Some of material parameters are defined like:

model.material('mat1').propertyGroup('def').func('eta').set('pieces', {'200.0' '1600.0' '-8.38278E-7+8.35717342E-8*T^1-7.69429583E-11*T^2+4.6437266E-14*T^3-1.06585607E-17*T^4'});

Please, would you help me to get the value of 'eta' in matlab livelink?
Is there any way to evaluate a piecewise function or analytical function defined in material node?

Best regards