Thanisararat Saleesung.. An investigation of Peroxide/co-agent crosslinking in EPDM rubber as an alternative to sulphur in mechanical goods. Doctoral Degree(Polymer Science and Technology). Mahidol University. Mahidol University Library and Knowledge Center. : Mahidol University, 2014.
An investigation of Peroxide/co-agent crosslinking in EPDM rubber as an alternative to sulphur in mechanical goods
Abstract:
The main use of ethylene propylene diene terpolymer (EPDM) is typically for the applications requiring a high service temperature. Therefore, the peroxide crosslinking system is required since the carbon-carbon bond generated possesses higher thermal stability than a sulphidic bond. This system involves a free radical process. There are numerous parameters affecting the crosslink efficiency, and thus product properties. This research focused on 3 types of organic peroxides: dicumyl peroxide (DCP), di(t-butylperoxy)diisopropylbenzene (Luperox F), and 2,5-dimethyl-2,5-di(tbutylperoxy) hexane (Luperox 101). The mixer set temperature, peroxide loading, and scorch controlling were also varied. The first objective was to investigate the effect of mixer set temperature on processability and properties of EPDM compounds and its crosslinked products. Results obtained revealed that the increase in mixer set temperature leads to a scorching of the rubber compound. The relative amounts of the free radical decomposition products of peroxide play a strong role on network structure and mechanical properties of EPDM vulcanisates. Results obtained from the second objective, regarding the peroxide loading effect exhibited that the crosslink density and mechanical properties of EPDM vulcanisates can be enhanced by increasing the peroxide loading. Moreover, the correlation of crosslink density determined by NMR and conventional techniques was investigated. The results demonstrated a good agreement between the two techniques. For the final objective, the delay of scorching by the uses of two types of scorch retarders: (i) the retarder was incorporated into commercial peroxide (SP) and (ii) that was supplied in the commercial co-agent (Saret) and was investigated. The result showed that the SP can alleviate the scorch problem more effectively than the use of Saret.