Swell Ratio Tester (SRT™)


The SRT™ measures the swelling ratio of crosslinked polymers as they are placed in a good solvent. From Flory's network theory, the data can be used to calculate the crosslink density, molecular weight between crosslinks, and the number of crosslinks/chain. Download more information below, or go to the applications notes section. The SRT test is in compliance with ASTM F2214-02 “Standard Test Method for In Situ Determination of Network Parameters of Crosslinked Ultra High Molecular Weight Polyethylene (UHMWPE)”. This instrument was developed under an SBIR grant from the NSF.

Principals of Operation

A test sample is placed in a temperature controlled chamber, which is filled with the solvent. A probe sits on the sample. As the temperature is raised to the desired temperature, a laser micrometer monitors the position of the probe, effectively determining the time-dependent change in height of the sample. Both the kinetics and the steady state swell ratio can be monitored.


The SRT™ is a compact instrument that can easily fit in a fume hood or on a benchtop. Using the custom SRT software, a laptop computer controls the instrument and collects the sample swelling data according to user defined test methods. The software has a data analysis module and calibration subroutine. An add-on software module allows users to program multiple temperature steps during a single run to determine temperature-dependent swelling behaviors.

CPG recently introduced a 3-station SRT (the SRT-3™), which allows simultaneous testing of 3 samples at once, all run from a single computer. The SRT-3 includes an elevating sample chamber for easier sample loading.

For more Information contact CPG using our contact us page.

SRT™ Brochure

More information can be found in our application notes section.

A report prepared by the Naval Surface Warfare Center evaluating the SRT-1 is available for download