Thiol Addition to Epoxidized Natural Rubber: Effect on the Tensile and Thermal Properties

Abstract

Epoxidized natural rubber (ENR) samples of various epoxidation degrees were synthesized from natural rubber (NR) latex, and 25 mole% epoxide of ENR was used to prepare ENR room temperature-curable films for coating applications. The films were prepared from rubber solutions. Trimethylolpropane tris(2-mercaptoacetate) (TMP-SH) was used as a curing agent. The effect of the thiol additive on the tensile and thermal properties of epoxidized natural rubber (ENR) was investigated. For the sake of comparison, NR and TMP-SH-containing formulations were also prepared.

It was observed that the addition of TMP-SH improved the tensile, thermal and swelling properties of ENR, indicating the formation of crosslinks. On the other hand, the addition of TMP-SH didn't improve the properties of NR, indicating the absence of reaction with TMP-SH. On the basis of data on the properties of the ENR films of this work it is demonstrated that these are appropriate for coating applications.

Keywords:

• coatings
• crosslinking
• epoxidized natural rubber
• tensile properties
• thermal properties
• thiol

The authors are indebted to the CNPq, CAPES and FUJB agencies for the financial support, to BRENTAG Química Brasil Ltda for the donation of the surfactant, and to TEADIT Indústria e Comércio Ltda for donation of the natural rubber latex.

Notes

^a Parts per hundred parts of rubber.