--- title: ASTM D6204 Part A Discover Molecular Properties Using an RPA description: Utilizing the rubber RPA, ASTM D6204 gives key insights into rubber and polymer molecular properties. Including AWD, MWD and long chain branching. image: https://resource.montechusa.com/hubfs/Molecular-Properties-Explained-Tile_04.jpg --- [![MonTech](https://resource.montechusa.com/hs-fs/hubfs/MonTech%20Rubber%20Testing%20Solutions.png?width=500&height=160&name=MonTech%20Rubber%20Testing%20Solutions.png "MonTech")](http://www.montechusa.com) # ASTM D6204 Method A Explained ## **ASTM D6204 Part A is one of the key tests for determining molecular properties of polymers and rubber compounds. ** The [Rubber Process Analyzer](https://www.montechusa.com/products/rubber-process-analyzer) is quickly being adapted into laboratories for advanced rubber characterization capabilities. ASTM D6204 is a three part test that measures molecular properties, processability and non-isothermal curing information of elastomers. The video below focuses on part A, highlighting molecular properties. Together we will show how RPA testing provides insights into average molecular weight, molecular weight distribution and long chain branching characteristics. **Click the video below to begin!**     [![Learn More About the RPA](https://no-cache.hubspot.com/cta/default/4109989/abcd5a37-7c4e-4341-9026-05ca7d00f1a1.png)](https://cta-redirect.hubspot.com/cta/redirect/4109989/abcd5a37-7c4e-4341-9026-05ca7d00f1a1)   ### Have questions about RPA Testing? Contact us and one of our experts will provide the answers you need! © 2026 MonTech USA. All Rights Reserved.