Product category:
Liquid Analysis: pH, Conductivity, ISE
News Release from: Metrohm UK | Subject: Thermal stability of PVC
Edited by the Processingtalk Editorial
Team on 28 January 2004
pH and conductivity measurement compared
for PVC
pH and conductivity measurement methods for the determination of thermal stability of PVC pellets and pieces were compared, showing that the evaluated stability times for both methods are equal
Comparison of pH and conductivity measurement for the determination of thermal stability of PVC pellets and pieces The thermal stability of PVC was determined under identical conditions according to ISO 182-2 (pH method) and ISO 182-3 (conductivity method)
This article was originally published on Processingtalk on 19 Jan 2004 at 8.00am (UK)
Related stories
Determination of the thermal stability of PVC
In 1999 Metrohm introduced the Thermomat, a dedicated instrument for determining the thermal stability of PVC and PVC products, a well approved method for PVC Quality Control
The stability and induction times obtained with the different indications were compared.
The experiments showed that the evaluated stability times for both methods are equal within the normal result scatter.
In contrast the induction time determined with the pH method is significantly shorter than the one found by conductivity.
The discrepancy can be explained by the difference in the data presentation, logarithmic scaling for the pH and linear for conductivity.
If the pH is converted into H+ concentration the obtained induction times are comparable.
Since ISO 182-2 only specifies the determination of the stability time, there is no restriction to use the 763PVC Thermomat for the determination of the thermal stability of PVC according to the ISO standards. Request a free brochure from Metrohm UK ...
• Metrohm UK: contact details and other news
• Email this article to a colleague
• Register for the free Processingtalk email newsletter
• Processingtalk Home Page
Search the Pro-Talk network of sites
