Creep and Dynamic Mechanical Analysis Studies of Peroxide‐Crosslinked Ethylene‐Octene Copolymer

Abstract

An ethylene‐octene copolymer (EOC) (45 wt% octene) is crosslinked using dicumyl peroxide (DCP). Differential scanning calorimetry (DSC) reveals a very low melting temperature (50 °C). The network density is evaluated by gel content. While 0.2–0.3 wt% of peroxide leads only to a molecular weight increase (samples completely dissolved in xylene), 0.4–0.6 wt% of peroxide caused network formation. High‐temperature creep was measured at 70, 120, and 200 °C at three stress levels. At 200 °C and above 0.6 wt% of peroxide, degradation due to chain scission is observed by rubber process analyzer (RPA) and is again supported by creep measurements. Residual strain at 70 °C is found to improve with increasing peroxide level. Dynamic mechanical analysis (DMA) reveals a strong influence of peroxide content on storage modulus and tan δ, in particular in the range 30–200 °C.

Influence of Electron Beam Irradiation on High‐Temperature Mechanical Properties of Ethylene Vinyl Acetate/Carbon Fibers Composites

“…We have found an exponential decrease in creep compliance with increasing level of radiation in our previous study of ethylene-octene copolymer[26]. Creep reduction with increasing level of cross-linking (by the addition of peroxide) was also reported by Theravalappil et al[27].…”

Crystallization, structure, and enhanced mechanical property of ethylene‐octene elastomer crosslinked with dicumyl peroxide

“…There are mainly three different ways to crosslink ethylene–octene copolymer: irradiation crosslinking, 8–12 silane grafting 13–17 and peroxide crosslinking 18–26 . Dicumyl peroxide (DCP) is the most commonly used crosslinking agent for peroxide crosslinking.…”

“…Crosslinking POE with DCP obeys the general framework of the theories on random crosslink polymers, and CH 2 ‐ makes main contribution to the crosslinking 25,26 . In case of peroxide crosslinking, substantial studies have been carried out on the crosslinking kinetics, 23,24 the influence of peroxide levels, various temperatures, different ethylene–octene copolymers and the mechanical property 18–22,25,26 . In fact, there are two different processing procedures to crosslink POE with DCP.…”

“…One of the approaches is to mix POE and DCP in melt state and then heat it up to a higher temperature to finish the crosslinking 19,21,24–26 . Another approach is to mix POE and DCP in melt and then cool it down; the blend is heated up for crosslinking at a later time 7,18,23 . The effects of crosslinking on the crystallization and structure of POE, crosslinked with the one step process (the first approach) method, were studied by Liao et al 19,24 using differential scanning calorimetry (DSC), NMR spectroscopy and X‐ray diffraction analysis (XRD).…”

“…The effects of crosslinking on the crystallization and structure of POE, crosslinked with the one step process (the first approach) method, were studied by Liao et al 19,24 using differential scanning calorimetry (DSC), NMR spectroscopy and X‐ray diffraction analysis (XRD). P Svoboda et al 7,18,23 utilized rubber process analyzer (RPA) and DSC to study different ethylene–octene copolymers, peroxide crosslinked with the second approach and with various peroxide levels. However, there are still some fundamental issues related to the crosslinked material, which are important but lack of fundamental understanding, such as, the different effects of crosslinking (with peroxide) uniformly throughout the material (the first approach above) and crosslinking its amorphous phase only (the second approach above) on crystallization dynamics and thermal properties.…”