The dynamic mechanical analysis is actually the preferred tool for evaluation of plasticization efficiency in macromolecular systems. The free volume theory indicates that the incorporation of small plasticizer molecules into the polymer increases the free volume of the system, enabling thereby enhanced chain mobility of the polymer - this is manifested by increasing the height and intensity of the tan delta parameter as well as shifting the peak maximum to the lower values.

There are a few approaches that DMA offers to quantify the plasticizer effects. The most common protocols involve the following:

(1) running temperature-sweep experiments at a fixed deformation frequency followed by an analysis of the location and intensity of tan delta;

This is the most often studied procedure. In case of low-intensity peaks (typical for polymers having rigid backbones), a reduction in deformation frequency should give slightly sharper signals. The storage modulus in the glassy state is also expected to be reduced due to the increased free volume and conformation possibilities.

(2) running frequency-sweep experiments with stepwise heating over the entire glass-rubber transition;

The procedure involves a complex post-analysis of the apparent activation energy of the relaxation processes occurring during the transition from the enthalpy-dominated state (below Tg) to the entropy-elastic state (above Tg) based on the Arrhenius-type models (e.g. Brostow model). There is a bunch of available literature that describes the protocol in detail.

Could you indicate DMA test conditions and maybe show an exemplar DMA plot of a system you are studying?

You may compare the intensity of TanD which is an indicative parameter for the stiffness of specimen and can be correlated with the mobility and dynamics of chains. I think higher plasticizing efficiency yields higher peak intensity.

Dear Ali Durmus,

Thank you for your responce. I've precized the question, because hard to define plasticizing efficiency basing on DMA results (eg. mechanical test and xrd should be considered too). High intensity inform about chain mobility, but it can indicate phase separation (however, meybe loss modulus is more appropriate for this investigation). My Tan Delta curves for some materials have low intensities, but polymer is well plasticized (highly amorphous, high elongation at break). I wonder if there is any method/equation for estimate and reach some number values that inform about mutual miscibilty from DMA results.

The dynamic mechanical analysis is actually the preferred tool for evaluation of plasticization efficiency in macromolecular systems. The free volume theory indicates that the incorporation of small plasticizer molecules into the polymer increases the free volume of the system, enabling thereby enhanced chain mobility of the polymer - this is manifested by increasing the height and intensity of the tan delta parameter as well as shifting the peak maximum to the lower values.

There are a few approaches that DMA offers to quantify the plasticizer effects. The most common protocols involve the following:

(1) running temperature-sweep experiments at a fixed deformation frequency followed by an analysis of the location and intensity of tan delta;

This is the most often studied procedure. In case of low-intensity peaks (typical for polymers having rigid backbones), a reduction in deformation frequency should give slightly sharper signals. The storage modulus in the glassy state is also expected to be reduced due to the increased free volume and conformation possibilities.

(2) running frequency-sweep experiments with stepwise heating over the entire glass-rubber transition;

The procedure involves a complex post-analysis of the apparent activation energy of the relaxation processes occurring during the transition from the enthalpy-dominated state (below Tg) to the entropy-elastic state (above Tg) based on the Arrhenius-type models (e.g. Brostow model). There is a bunch of available literature that describes the protocol in detail.

Could you indicate DMA test conditions and maybe show an exemplar DMA plot of a system you are studying?

I agree with Pawel. In fact some plasticizers having solubilizing tendency are used with semicrystalline polymers. If it is so, you may get different type of tan delta curve, with shoulder or uneven. Check with changing scales

I would add, that, depending on plasticization mechanism, quite sensitive to plasticization may be Tan D peak associated with beta transition - characterizing intensity of local, non-cooperative chain mobility. If a plasticizer caused free volume of the system to increase (as Pawel has mentioned), in-chain mobility can be expected to also increase, leading to higher intensity of TanD beta-transition peak.

Dear Michael Shuster

Thank you for your comment.

In my work, problem is more complex. Some of tan delta curves have oblate beta relaxation peaks, but samples as xrd, mech. test, ftir and general visual characetrization indicated, are plasticized. These plasticizers are also solvent for polymer, so im wondering if it is possible to evaluation potential partial dissolution of polymer with DMA technique. For plasticizers that are not solvents an interpretation is more easy (high tan delta peaks, a lot of literature that can be an reference).

BR, Magdalena