AbstractIn the synthesis of low‐density polyethylene there is a direct relationship between the synthesis conditions, molecular structure, and technical properties of the product. The evaluation of the molecular structure of the polymer is therefore important. The most important structure parameters in low‐density polyethylene are molecular weight distribution (MWD), degree of long‐chain branching (LCB), and short‐chain branching distribution (SCBD). Through chain transfer to polymer it is possible to get composite molecules made up of chains with different amounts of short‐chain branching. By using temperature rising elution fractionation (TREF) and plotting the methyl contents or the DTA melt temperature of the fractions as functions of the elution temperature, the SCBD within composite molecules can be evaluated. The deviations from linear relationships are caused by such SCBD within composite molecules. In order to demonstrate the buildup of composite molecules, samples from different parts of a reactor were investigated.