thermal behavior of ethylene/1-octene copolymer fractions at high temperatures: effect of hexyl branch content

In this work, the effect of hexyl branch content on thermal behavior of a fractionated ethylene/1-octene copolymer with emphasis on high temperatures was investigated. the ethylene/1-octene copolymer was carefully fractionated to different fractions with homogenous hexyl branch (hb) content by preparative temperature rising elution fractionation (p-tref) method. the p-tref fractions were thermally analyzed via differential scanning calorimetry (dsc), thermogravimetric analysis (tga) and evolved gas analysis (ega). the p-tref profile showed a short chain branch distribution (scbd) of around 1.24. a linear relationship between p-tref elution temperature (et) and methylene sequence length (msl) was presented. the dsc curves exhibited a monolithically increase in melting temperature (tm) as well as crystallization temperature (tc) with decreasing short chain branch (scb) content. the calculated values of lamellae thickness suggested a linear function of scb content and tm. the tga studies of p-tref fractions depicted a two-stage thermal degradation behavior: pre-degradation and main degradation stages. tmax for both pre-degradation and main degradation stages increased for fractions with less hexyl branch content. as an interesting point the pre-degradation stage was more intensified for more linear fractions. the concentration of main products was found to be affected by the content of hexyl branches using py- gc-ms.