NMR study of ring opening reaction of epoxidized natural rubber in presence of potassium hydroxide/isopropanol solution

作者：Dahham Omar S; Hamzah Rosniza^*; Abu Bakar Mohamad; Zulkepli Nik Noriman; Dahham Saad S; Ting Sam Sung

来源：Polymer Testing, 2017, 59: 55-66.

DOI：10.1016/j.polymertesting.2017.01.006

• Epoxidized natural rubber
• Ring opening reaction
• Epoxide
• Nuclear magnetic resonance
• Thermal characteristic

The ring opening reaction of epoxidized natural rubber (ENR-50) in the presence of potassium hydroxide/isopropanol solution was studied using NMR, and it's thermal characteristic was investigated using TG/DTG and DSC. H-1-NMR showed that 16.9% of epoxide units was ring-opened in treated ENR-50, which was also supported by quantitative FTIR spectroscopy. C-13-NMR proved the location of alkyl group (isopropyl) in the polymer chain of treated ENR-50. The attachment location of isopropyl occurred at both most (up arrow) and least (down arrow) hindered carbons of the epoxide. 2D-NMR was used to identify and scrutinize the triad assignment of treated ENR-50. The TG/DTG results presented three decomposition steps at 190331, 331-521 and 521-706 degrees C due to the existence of mixtures of polymer chains i.e. ring-opened and intact epoxide of ENR-50, which also led to increase in T-g of treated ENR-50 at 13.2 degrees C compared with purified ENR-50 at 17.7 degrees C.

• 出版日期2017-5