cathetometer

The stress--strain measurements were obtained using either an Instron 5581 equipped with a noncontacting extensimeter or a Hounsfield extensimeter equipped with a cathetometer to allow precise measurements of the extension of the sample.

A cathetometer was used to observe the liquid meniscus through an opening in the polystyrene insulation of the bath.

A cathetometer KM-8 was used in our work (measurement accuracy [+ or -] 0.001 mm) [6].

To obtain control value of hydraulic permeability, known pressure was applied on compartment C, and the consequent volume flux (Jv) was measured by noting the rate of advancement of liquid meniscus in the capillary attached to the compartment D, using a cathetometer reading up to 0.001 cm and a stopwatch reading up to 0.1 sec.

At the beginning of each experiment, the solvent vapor was introduced into the column, and the interaction between the polymer and solvent was monitored by measuring the mass uptake using a cathetometer. The experiment was concluded when there was no further change in the extension of the spring.

A cathetometer having a precision of 0.01 mm was used to measure the difference in the height of the sample from which a fractional change in the volume of the polymer was calculated.