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Elvaloy® RET is a random terpolymer comprising ethylene, normal butylacrylate and glycidyl methacrylate (GMA). The molecular weight and comonomer levels can be varied during polymer manufacture. It is the GMA portion of the molecule that appears to be responsible for the reaction observed when Elvaloy® is mixed and heated with asphalt.
EGA copolymers chemically react with asphalt to form a polymer-linked-asphalt system with improved performance properties. The epoxide ring in the glycidal structure is believed to undergo an addition reaction with various functional groups in a typical asphaltene molecule. The asphaltenes, which can have carboxylic acid functionality, open the epoxy ring and form an aromatic ester. This type of reaction is consistent with the I.R. and D.S.C. trace of the extracted reaction product. The D.S.C. also indicates that the reaction is 40 to 50 percent asphaltene like material.
Polymers with higher levels of GMA have been and evaluated in asphalt. These polymers appear to allow the use of less polymer to give the same response in high temperature SHRP properties.
After reaction, the Elvaloy® RET terpolymer is covalently bonded to the asphaltene molecule and will not separate.
In a separation test performed on asphalts containing 2 percent RET and 5 percent SBS, both samples were stored for 5 days at 139 degrees C and the ring and ball softening points were measured on the top and the bottom portions of the samples. The test results clearly indicates that that the SBS floated to the top, while the Elvaloy® RET did not separate in the binder.
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How Elvaloy® reacts with asphalt
