Technical Paper Archive


This site contains all papers presented at Rubber Division, ACS Technical Meetings from 2000-2018. Meetings prior to 2000 are incomplete and papers are added as they are digitized.


For older papers not listed here, please send your request, including Meeting Year, Title, Author, and Paper # to: cbrady@rubber.org


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An Original Approach to Determine Cross-link Densities in Rubber Blends Using Solid-state NMR Experiments

C12 robin

Event: 200th Technical Meeting - Fall 2021
Location: Pittsburgh, PA
Date: October 05, 2021
Author: Clement Robin
Paper Number: C12

Price: $20.00

  • The final properties of rubber compounds are highly related to their cross-link density. Several analytical methods have been developed throughout the years to determine this key parameter. Among the possible approaches, solid-state NMR and more precisely, 1H double-quantum based experiments, has proven its reliability and its sensitivity. This method indeed leads to the distribution of the cross-link density, but also to an accurate quantification of the network defects (dangling chains and loops). If one considers elastomer blends, applying the double-quantum NMR approach under static conditions only gives access to the overall constraint density. In this work, a recent and original approach based on the Back-to-Back homonuclear double-quantum recoupling sequence, BaBa-xy16, is used in order to determine the cross-link density of each elastomer phase in a blend of Natural Rubber (NR) and poly(butadiene) (BR). Even though NR and BR share very similar chemical structures, a more detailed analysis can bring some major differences. Taking into consideration the potential partition of curatives and/or differences in the chemical reactivity of each polymer, one can easily imagine an uneven distribution of cross-link densities within each phase of these immiscible blends. To address this question, model NR/BR blends cross-linked with sulfur or peroxide were prepared and investigated through the BaBa-xy16 pulse sequence. The reliability of this new approach is discussed and compared to already existing, more usual techniques. Finally, we clearly believe that this method could contribute to get an in-depth understanding of the physical properties exhibited by rubber blends.

    Papers from 200th Technical Meeting - Fall 2021

    Items from 200th Technical Meeting - Fall 2021