Exploring a novel cyclic monofunctional peroxide for curing of silicone rubber at elevated temperature

Abstract

The curing characteristics of silicone rubber (polydimethylsiloxane [PDMS]) in the presence of structurally different peroxides, namely dicumyl peroxide (DCP) and 3,3,5,7,7-pentamethyl-1,2,4-trioxepane (PMTO), have been studied in details. At moderate temperature, DCP is more prominent for curing the silicone rubber but at high temperatures it suffers from low scorch safety. An inhibitor 2,2,6,6tetramethylpiperidinyloxyl (TEMPO) was added with DCP to stabilize the radicals in order to increase the scorch safety time. On the other hand, PMTO showed a prolonged scorch safety and better crosslinking efficiency rather than (DCP 1 TEMPO) mix at higher temperatures. PMTOcrosslinked PDMS shows better crosslinking efficiency as indicated by a higher gel content and low swelling index value. Also the mechanical properties, thermal stability, and dynamic mechanical behavior of PMTO-crosslinked PDMS are much superior than (DCP 1 TEMPO)-crosslinked PDMS. Apart from thermoplastic vulcanizates (TPVs) made from PMTO-crosslinked PDMS show better physicomechanical behavior compared to the TPVs made from (DCP 1 TEMPO)crosslinked PDMS. Moreover, DCP undergoes decomposition reactions at a higher temperature and forms acetophenone, which leads to an unpleasant smell in the final products whereas no such phenomenon is observed for PMTO. Therefore, PMTO turns out to be the suitable peroxide for crosslinking of PDMS at higher temperature. POLYM. FIG. 11. Storage modulus (E 0 ) of (DCP 1 TEMPO)-and PMTOcrosslinked PDMS. FIG. 12. Temile stress versus strain diagram.

A relative study of the effect of static and dynamic vulcanization upon shape memory nature of thermally actuated peroxide crosslinked polyolefinic blends

“…The gel content percentage of the uncrosslinked EOC‐EPDM blend and both statically vulcanized and dynamically vulcanized EOC‐EPDM blend was calculated by the extraction of sol components in boiling xylene for 24 h using a soxhlet apparatus. Percentage gel content of the samples was calculated using the equation given below: [ 31 ] W 1 stands for the weight of the dried sample after extraction and W 0 represents the weight of the sample before extraction. After soxhlet extraction, the extracted samples were dried in an oven at 50°C until the extracted sample reach a constant weight.…”

Automotive applications of thermoplastic vulcanizates

“…TPVs were prepared at a fixed ratio of 50/50 wt% of PDMS and PA12 exploring various peroxides say dicumyl peroxide (DCP), 3,3,5,7,7-pentamethyl 1,2,4-trioxepane (PMTO) and cumyl hydroperoxide (CHP). [81,82] Although both PDMS and PA12 are highly thermally stable, the poor physicomechanical behavior restricts its application for the purpose of high heat and oil resistant application purpose. The poor physicomechanical behavior is only due to the lack of interfacial compatibility between the PDMS phase and PA12 matrix phase.…”

“…Apart from in the year of 2013, Chatterjee et al also explored a new system of TPV based on silicone rubber (PDMS) and PA12 in order to develop the high heat and oil resistant TPV. TPVs were prepared at a fixed ratio of 50/50 wt% of PDMS and PA12 exploring various peroxides say dicumyl peroxide (DCP), 3,3,5,7,7‐pentamethyl 1,2,4‐trioxepane (PMTO) and cumyl hydroperoxide (CHP) . Although both PDMS and PA12 are highly thermally stable, the poor physicomechanical behavior restricts its application for the purpose of high heat and oil resistant application purpose.…”

Development and characterizations of ultra‐high molecular weight EPDM/PP based TPV nanocomposites for automotive applications

“…First, the present understanding of composite behavior does not fully satisfy or predict from a scientific standpoint why these systems are superior in many of its properties. [21,22] Therefore, the primary objective of this work is to develop TPV nano composite (TPVNs) by using new generation UHMW EPDM rubber with nano-clay and nanosilica for the application in automotive sector and it should also exhibit very good physico-mechanical properties. To prepare a new generation TPVNs, EPDM rubber, and PP thermoplastic have been taken for this study.…”

“…First, the present understanding of composite behavior does not fully satisfy or predict from a scientific standpoint why these systems are superior in many of its properties. [ 21,22 ]…”