TRACKER - EXAMPLE 1

INTRODUCTION :

This example shows how, with the TRACKER, we can measure the surface tension of a melted polymer at 225°C.

PROTOCOL :

We form a hanging drop of polymer in air, in a closed and heated precinct, at 225°C. The melted polymer is storedin the syringe and a drop is formed at the tip of the syringe. For the filling, the syringe and the polymer are pre-heated at 240 °C in a drying room. So, it is easy to fill up the syringe because the polymer is liquid. Then, the syringe is set in a pre-heated cell, at about 220°C. The first drop has been formed after about one hour of stable temperature, at 225°C. Measurements have been made on two drops of 10µl each. The polymer’s voluminal mass is equal to 1,25 g/cm3 .

RESULTS :

The next graphic shows the surface tension recording for about 40 minutes.

Comments :

These results are perfectly valid because drops of polymer are laplacian.

Each examples show that, the cloud points of the drop’s profile remains dispersed so as to be homogeneous round its profile determined using the Laplace's equation.

MEASUREMENT 1 : AFTER 15 minutes DROP OF MELTED POLYMER AT 225 °C	MEASUREMENT 2 : AFTER 30 minutes DROP OF MELTED POLYMER AT 225 °C

Note :

These results have been obtained when the TRACKER was still working under DOS.

CONCLUSION

The measurement of the surface tension of the melted polymer with the drop method ( with the TRACKER) is perfectly possible and there are not particular operative difficulties.