Thermostability of PVC and related chlorinated polymers

Summary

The determination of the thermostability of PVC (also called dehydrochlorination test or DHC test) characterizes the stability of polyvinyl chloride or related chlorinated polymers against heat exposure.

During the test, nitrogen is passing over the sample in the reaction vessel at constant elevated temperature. When the sample decomposes, hydrochloric acid gas is formed which is transported into the measuring vessel by the nitrogen stream and absorbed in the measuring solution (deionized water). The continuously recorded electrical conductivity of the measuring solution increases due to the absorption of the HCl gas. Thus, its appearance can be detected. The time until the conductivity has changed by a predefined value is called stability time and characterizes the thermostability of the PVC material.

The determination of the thermostability of PVC is described according to DIN 53381 part 1 or ISO 182 part 3 using the 895 Professional PVC Thermomat. The test is suitable for monitoring of the manufacture and processing, for a delivery check, for the characterization and comparison of PVC products as well as for testing the effectiveness of heat stabilizers in molded PVC materials. This Application Bulletin provides a detailed description including necessary sample preparation steps.

Samples

Polyvinyl chloride (PVC) or related chlorinated polymers

Instruments

>> Download the full Application Note as PDF

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