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.