Epoxidized Natural Rubber Measurement

When natural rubber (NR) latex is epoxidized, it is converted to a new plastic (Epoxidized Natural Rubber or ENR) with many favorable properties. Damping and anti-vibration characteristics are improved. ENR is oil resistant and has a better air impermeability i.e. better sealing properties. ENR is a speciality polymer produced from natural rubber latex, cis 1.4 – polyisoprene, with epoxide groups randomly dispersed along the polymer backbone. Two grades are available commercially, ENR 25 and ENR 50, indicating 25% and 50% epoxidation respectively.

Measurement of Epoxy Content
Expensive and large Nuclear Magnetic Resonance (NMR) spectrometers are currently used to determine the epoxy amount in ENR. In recent years however, more affordable bench top type NMR systems with smaller magnets have been been developed. With a few modifications it is now possible to measure the ENR concentration with a small table top NMR system.
Fig 1. Bench Top NMR System

The  Implementation of a NMR-T1-Filter separates the epoxy and rubber signals nicely. This allows to determine the amount of epoxy easily.

Fig. 2. ENR-10, 25, 50 measurements

Today ENR-25 and ENR-50 are used in many applications and new product developments are on the way in the apparel industry (foot wear), automotive industry (tires) and many others.
The new bench top NMR based quantification of epoxy will allow manufacturers to optimize their production processes efficiently. Buyers of ENR have a handy tool to control their purchase and guarantee fair trade.
The procedure is based on the method UPB/P/022, released and approved by the Malaysian Rubber Board (MRB).

For more information contact info@krusp.com